1
00:00:00,029 --> 00:00:07,089
it's a rude awakening and mornig welcome
to do with the uh... third week of

2
00:00:07,089 --> 00:00:10,769
medical school for you you might have
noticed that our

3
00:00:10,769 --> 00:00:13,679
cohort of medical students has that
doubled

4
00:00:13,679 --> 00:00:17,081
in size if you guys have noticed you if
you're here first of all the job finding

5
00:00:17,081 --> 00:00:19,078
this other lecture hall sorry work

6
00:00:19,078 --> 00:00:22,034
jumping you from place to place but this
is part of

7
00:00:22,034 --> 00:00:23,048
trying to revamp

8
00:00:23,048 --> 00:00:26,779
all of our lecture halls and so we had
to do this in a stage process those of

9
00:00:26,779 --> 00:00:28,529
you that understands gantt charts

10
00:00:28,529 --> 00:00:29,769
and construction

11
00:00:29,769 --> 00:00:32,046
will uh... will sympathize but you found
the place

12
00:00:32,046 --> 00:00:35,689
in north lecture hall now are your
colleagues here and suits

13
00:00:35,689 --> 00:00:39,018
they are a great source of advice

14
00:00:39,018 --> 00:00:44,064
and uh... and uh... being able to and
sort of queries about different staff so

15
00:00:44,064 --> 00:00:46,289
now you've got your built-in

16
00:00:46,289 --> 00:00:50,219
counselors uh... here but they're also
going to be very busy as you notice they

17
00:00:50,219 --> 00:00:54,009
probably probably noticed they started
about an hour before you did so

18
00:00:54,009 --> 00:00:55,039
for

19
00:00:55,039 --> 00:00:57,469
that's what you have to look forward to
it here

20
00:00:57,469 --> 00:00:58,064
that that

21
00:00:58,064 --> 00:00:59,053
uh...

22
00:00:59,053 --> 00:01:04,022
hope you guys survived your first quiz
hopefully it wasn't too painful i know

23
00:01:04,022 --> 00:01:06,009
many people ask will they be medical
decision making

24
00:01:06,009 --> 00:01:10,015
stuff on the quiz and the answer to that
was

25
00:01:10,015 --> 00:01:11,015
uh...

26
00:01:11,015 --> 00:01:14,079
remember that genetics in pathology or
the big components of the quizzes and

27
00:01:14,079 --> 00:01:18,087
that we in india and we have assignments
so you turned in your first assignment

28
00:01:18,087 --> 00:01:20,909
last thursday at small groups

29
00:01:20,909 --> 00:01:23,036
uh... i'm in the process of reviewing
them

30
00:01:23,036 --> 00:01:25,088
they will get back to you in your mail
boxes

31
00:01:25,088 --> 00:01:28,074
uh... so you will be have them to study
from

32
00:01:28,074 --> 00:01:32,459
i will also when i return them to you
you should pay attention on c_ tools all

33
00:01:32,459 --> 00:01:35,061
publisher ultimate which will also have
the answer key

34
00:01:35,061 --> 00:01:37,419
to interview uh... assignments

35
00:01:37,419 --> 00:01:41,159
so there's no hidden doctors here it'll
be a turkey will give you an explanation

36
00:01:41,159 --> 00:01:45,189
to each of the questions that way you
can look at your answer what banter in

37
00:01:45,189 --> 00:01:47,003
turkey was any notes that you had

38
00:01:47,003 --> 00:01:48,909
and reconcile and if there are any

39
00:01:48,909 --> 00:01:52,299
other questions certainly we're here to
help you

40
00:01:52,299 --> 00:01:55,002
you have another small group tomorrow
afternoon

41
00:01:55,002 --> 00:01:58,024
that will largely be based on material
that we cover today

42
00:01:58,024 --> 00:02:01,067
uh... hopefully if you guys have had a
chance to get a jump start on that i try

43
00:02:01,067 --> 00:02:03,009
to post in a week in advance

44
00:02:03,009 --> 00:02:04,549
you're more then welcome to

45
00:02:04,549 --> 00:02:08,014
uh... reading ahead is hopefully fine
encouraged if you want to do want to

46
00:02:08,014 --> 00:02:09,006
that's totally fine as well

47
00:02:09,006 --> 00:02:12,009
there should be enough time to be able
to complete that again it's the same

48
00:02:12,009 --> 00:02:12,939
protocol

49
00:02:12,939 --> 00:02:15,052
bring it to your small group still
discuss that with here

50
00:02:15,052 --> 00:02:18,989
co students in your small group silkair
and then returned them

51
00:02:18,989 --> 00:02:22,959
uh... tournament and then i'll be
returning to you in a timely fashion

52
00:02:22,959 --> 00:02:29,065
any questions about the logistics of
this course for this part of this force

53
00:02:29,065 --> 00:02:31,519
so why don't we go ahead and get started

54
00:02:31,519 --> 00:02:32,699
uh...

55
00:02:32,699 --> 00:02:35,929
today we're going to be for we're gonna
be picking up a little bit where we left

56
00:02:35,929 --> 00:02:37,049
off

57
00:02:37,049 --> 00:02:38,069
last time

58
00:02:38,069 --> 00:02:42,091
and he wants start by declaring uh...
any industry relationships

59
00:02:42,091 --> 00:02:46,046
that i might add to contacts that meet
your otherwise

60
00:02:46,046 --> 00:02:48,209
in the answer is

61
00:02:48,209 --> 00:02:50,569
certain factor

62
00:02:50,569 --> 00:02:52,459
uh... dancers is i have not been

63
00:02:52,459 --> 00:02:53,309
to disclose

64
00:02:53,309 --> 00:02:55,959
so nothing that would uh... interfere
with my ability to present you an

65
00:02:55,959 --> 00:02:59,269
objective view of uh... medical decision
made

66
00:02:59,269 --> 00:03:03,739
so our first just returning to where we
left off with their first thread

67
00:03:03,739 --> 00:03:07,479
this is around information retrieval
focusing on asking in acquiring

68
00:03:07,479 --> 00:03:09,169
if you remember and

69
00:03:09,169 --> 00:03:13,239
after last monday we left off by talking
about the way the structure well

70
00:03:13,239 --> 00:03:16,219
foreground question and these are sort
of that

71
00:03:16,219 --> 00:03:18,789
uh... fundamental tools that were
required to

72
00:03:18,789 --> 00:03:22,509
af but good questions get the
information from the literature and then

73
00:03:22,509 --> 00:03:26,064
interpret and apply them as a way to
focus a little bit just to revisit

74
00:03:26,064 --> 00:03:28,066
this tool that we talked about

75
00:03:28,066 --> 00:03:32,006
this was the pico tool that encourage
you to just use it as a tool basically

76
00:03:32,006 --> 00:03:36,006
it's a way of specifying the different
elements in your question there will be

77
00:03:36,006 --> 00:03:36,909
important

78
00:03:36,909 --> 00:03:40,027
tour it ought to be able to sort out the
appropriate answers

79
00:03:40,027 --> 00:03:42,086
and we think it's important to be able
to do with in advance

80
00:03:42,086 --> 00:03:45,009
because by doing it in advance

81
00:03:45,009 --> 00:03:49,003
uh... you're really able to focus on
what you need and what your patients

82
00:03:49,003 --> 00:03:49,079
need

83
00:03:49,079 --> 00:03:54,087
so in order to practice doing this went
to ask you to do is to look at this case

84
00:03:54,087 --> 00:03:56,087
and practice with your partner

85
00:03:56,087 --> 00:03:58,239
jotting down the foreground

86
00:03:58,239 --> 00:04:00,849
uh... question so let me go over the
case real briefly

87
00:04:00,849 --> 00:04:03,072
because we're gonna be using this uh...
moving forward

88
00:04:03,072 --> 00:04:06,006
so this is now this is a forty
two-year-old woman

89
00:04:06,006 --> 00:04:09,559
who comes to her primary-care
practitioners office

90
00:04:09,559 --> 00:04:12,084
for follow-up of her diabetes and you're
the medical student

91
00:04:12,084 --> 00:04:14,006
she's currently on libby ride

92
00:04:14,006 --> 00:04:16,609
ten milligrams twice daily

93
00:04:16,609 --> 00:04:19,939
however her blood sugars still stay
elevated despite being on that

94
00:04:19,939 --> 00:04:21,379
medication delivery right

95
00:04:21,379 --> 00:04:22,919
after you see this patient

96
00:04:22,919 --> 00:04:24,649
you're attending asked whether you think

97
00:04:24,649 --> 00:04:28,028
she should admit foreman to her regimen

98
00:04:28,028 --> 00:04:31,053
pretend like you know what would your
ideas and pretend like you know what

99
00:04:31,053 --> 00:04:34,009
metformin is you may not but these are
both

100
00:04:34,009 --> 00:04:36,058
uh... it is that we use in diabetes

101
00:04:36,058 --> 00:04:39,034
we'll be right is the sole final you
react

102
00:04:39,034 --> 00:04:42,909
and metformin is uh... another agent
that we use

103
00:04:42,909 --> 00:04:45,011
uh... packets dvd

104
00:04:45,011 --> 00:04:48,049
uh... and i cant really pronounce what
that actually stands for it's a very

105
00:04:48,049 --> 00:04:50,027
difficult word to pronounce but

106
00:04:50,027 --> 00:04:54,006
suffice it to say good beer i can see
his your um... insulin

107
00:04:54,006 --> 00:04:58,053
uh... usa secretion but metformin
improves your sensitivity uh... to

108
00:04:58,053 --> 00:05:01,084
insulin is well or that your body makes

109
00:05:01,084 --> 00:05:03,052
so let's say you know all of that

110
00:05:03,052 --> 00:05:06,053
and the question i would ask you to do
is to start putting on

111
00:05:06,053 --> 00:05:09,088
your hat as if you were a clinician just
to get a sense of what

112
00:05:09,088 --> 00:05:13,289
these kind of foreground questions are
about remember therefore important

113
00:05:13,289 --> 00:05:14,569
components

114
00:05:14,569 --> 00:05:17,929
for a foreground question you have to
define the patient population that

115
00:05:17,929 --> 00:05:19,027
you're interested in

116
00:05:19,027 --> 00:05:21,028
you have to define the intervention

117
00:05:21,028 --> 00:05:22,819
that you're interested in

118
00:05:22,819 --> 00:05:26,459
the comparison group that would be part
of the study that might help you answer

119
00:05:26,459 --> 00:05:28,008
the question andy outcomes of interest

120
00:05:28,008 --> 00:05:31,639
that you would be that you in your
patient would be interested in

121
00:05:31,639 --> 00:05:35,046
this will help you then scanned the
literature to figure out what are the

122
00:05:35,046 --> 00:05:38,002
articles that would be most relevant

123
00:05:38,002 --> 00:05:39,849
for this particular case

124
00:05:39,849 --> 00:05:43,000
so i'd like you did it was turned your
partner and come up with one

125
00:05:43,000 --> 00:05:46,037
that would meet all four categories it's
a fairly straightforward exercise but

126
00:05:46,037 --> 00:05:47,058
wanna make sure that you get

127
00:05:47,058 --> 00:05:50,068
such answer practice that's so spent a
couple minutes doing that and we'll talk

128
00:05:50,068 --> 00:06:21,949
about it

129
00:06:21,949 --> 00:07:06,009
a

130
00:07:06,009 --> 00:07:09,009
okay three parking lot with remember
that really

131
00:07:09,009 --> 00:07:11,074
nobody answers here because

132
00:07:11,074 --> 00:07:15,669
every single uh... every single answer
that you would give each of the four

133
00:07:15,669 --> 00:07:18,037
different categories would have some
debate around

134
00:07:18,037 --> 00:07:22,031
whether the article that you retrieved
with those particular characteristics of

135
00:07:22,031 --> 00:07:23,041
the study population

136
00:07:23,041 --> 00:07:25,036
would actually help you answer your
question

137
00:07:25,036 --> 00:07:29,039
or not and the degree to which it would
do that so let's just hear some of the

138
00:07:29,039 --> 00:07:33,044
questions what i'd like you to do is not
the same like he was ex and i was

139
00:07:33,044 --> 00:07:34,055
uh... was why

140
00:07:34,055 --> 00:07:37,008
i'd like to see if you could stated in
the form of a question one that would

141
00:07:37,008 --> 00:07:39,319
contain all four

142
00:07:39,319 --> 00:07:40,849
of those different components

143
00:07:40,849 --> 00:07:41,719
just a little hint

144
00:07:41,719 --> 00:07:45,077
i might ask something like this uh... on
one of the either the assignments

145
00:07:45,077 --> 00:07:46,077
or certainly

146
00:07:46,077 --> 00:07:52,099
while our final examination as well so
who wants to take a stab at it

147
00:07:52,099 --> 00:07:54,949
them

148
00:07:54,949 --> 00:08:01,078
uh...

149
00:08:01,078 --> 00:08:04,199
okay great so here let me let me restate
this

150
00:08:04,199 --> 00:08:05,084
in women with diabetes

151
00:08:05,084 --> 00:08:09,939
what is the effect of metformin plus
glider ride

152
00:08:09,939 --> 00:08:12,053
blood sugar levels compared to drive me
right along

153
00:08:12,053 --> 00:08:16,019
so let's see if we got all the before
components in their is that patient was

154
00:08:16,019 --> 00:08:20,059
women with diabetes your intervention
was metformin it would be right together

155
00:08:20,059 --> 00:08:22,059
versus delivery right alone in the
outcome you're interested in

156
00:08:22,059 --> 00:08:25,269
was improvement in her blood sugar
levels okay

157
00:08:25,269 --> 00:08:28,339
so let's break that down the patient
population is that were women with

158
00:08:28,339 --> 00:08:30,076
diabetes was that it did anyone have
something different

159
00:08:30,076 --> 00:08:34,025
then women with diabetes here

160
00:08:34,025 --> 00:08:39,019
awesome al you specified in age cutoff
so women with diabetes over forty ok any

161
00:08:39,019 --> 00:08:39,759
other

162
00:08:39,759 --> 00:08:44,002
variabilities there

163
00:08:44,002 --> 00:08:48,002
asel na specifying gender so just all
patients with diabetes let's back up and

164
00:08:48,002 --> 00:08:48,969
think about that

165
00:08:48,969 --> 00:08:51,098
limelight it so that the question would
be if we're to get an article

166
00:08:51,098 --> 00:08:53,000
that had

167
00:08:53,000 --> 00:08:54,087
all ahead men and women

168
00:08:54,087 --> 00:08:56,049
in the past study population

169
00:08:56,049 --> 00:08:59,061
would we say that's ok to extrapolate
the results

170
00:08:59,061 --> 00:09:01,859
and then apply to this patient
population

171
00:09:01,859 --> 00:09:03,011
and so you said

172
00:09:03,011 --> 00:09:07,086
potentially that would be ok any reason
to think that verb rationale

173
00:09:07,086 --> 00:09:19,061
what goes through your mind as you're
making that call

174
00:09:19,061 --> 00:09:22,069
but the answer being that date one of
the rationale might be fifty-year

175
00:09:22,069 --> 00:09:24,058
defined studies where you have

176
00:09:24,058 --> 00:09:26,063
both genders represented as opposed to

177
00:09:26,063 --> 00:09:30,029
one gender alone so that's one certainly
one consideration what might be another

178
00:09:30,029 --> 00:09:36,008
consideration you would use

179
00:09:36,008 --> 00:09:39,056
uh... so now you're talking you're
getting even more specific saying

180
00:09:39,056 --> 00:09:40,649
impatience

181
00:09:40,649 --> 00:09:41,057
who are

182
00:09:41,057 --> 00:09:45,032
poorly controlled on good be ride with
diabetes

183
00:09:45,032 --> 00:09:48,065
what about the comparison group purses
uh... verses the intervention so that we

184
00:09:48,065 --> 00:09:49,249
another

185
00:09:49,249 --> 00:09:50,054
shape that you would be there

186
00:09:50,054 --> 00:09:53,052
but that you might use backing up to the
gender issue

187
00:09:53,052 --> 00:09:56,022
the question i would ask you to ask and
we ask this question all the time does

188
00:09:56,022 --> 00:09:59,044
the disease manifest differently or act
differently

189
00:09:59,044 --> 00:10:01,049
in one gender verses another

190
00:10:01,049 --> 00:10:03,098
does the disease manifest if really
inpatient over forty

191
00:10:03,098 --> 00:10:06,016
rice's those that might be younger than
forty

192
00:10:06,016 --> 00:10:09,002
those would be the questions that you
would be asking yourself and remember

193
00:10:09,002 --> 00:10:12,042
you have to build some background
knowledge about this subject before

194
00:10:12,042 --> 00:10:14,063
being able to ask the most sophisticated

195
00:10:14,063 --> 00:10:15,088
foreground question

196
00:10:15,088 --> 00:10:18,041
i'm trying to know a little bit about
the pathophysiology

197
00:10:18,041 --> 00:10:21,013
but it's reasonable to have those
different want uh... those those

198
00:10:21,013 --> 00:10:23,239
different shades of variation

199
00:10:23,239 --> 00:10:24,038
in the patient

200
00:10:24,038 --> 00:10:27,022
the intervention was metformin plus
we'll be right did anyone have a

201
00:10:27,022 --> 00:10:32,016
different intervention

202
00:10:32,016 --> 00:10:34,065
oddly be what we're thinking about the
kind that we're not talking about

203
00:10:34,065 --> 00:10:37,055
stopping the glitter ride and adding
metformin

204
00:10:37,055 --> 00:10:40,052
but in some cases you might be looking
for head to head comparison

205
00:10:40,052 --> 00:10:43,066
and in fact if you're thinking about it
from a drug company standpoint they may

206
00:10:43,066 --> 00:10:46,041
be interested in head to head
comparisons because they're trying to

207
00:10:46,041 --> 00:10:47,529
prove one

208
00:10:47,529 --> 00:10:49,083
at the at the efficacy of one drug over
another

209
00:10:49,083 --> 00:10:52,009
if you're thinking about it from the
standpoint of

210
00:10:52,009 --> 00:10:55,045
of uh... pathophysiology you might be
interested in head to head comparisons

211
00:10:55,045 --> 00:10:58,043
but if you're thinking about it in the
practical sense we often might be

212
00:10:58,043 --> 00:10:59,022
looking at

213
00:10:59,022 --> 00:11:02,054
adding and agent to an existing regimen

214
00:11:02,054 --> 00:11:04,409
those are less commonly found

215
00:11:04,409 --> 00:11:05,095
in the literature on just a tad

216
00:11:05,095 --> 00:11:09,031
and so you may be stuck saying well i
don't have an additional

217
00:11:09,031 --> 00:11:12,049
uh... i don't have a study that shows
the addition of metformin

218
00:11:12,049 --> 00:11:14,007
and so you would have to extrapolate

219
00:11:14,007 --> 00:11:15,389
from head to head comparison

220
00:11:15,389 --> 00:11:16,078
which is tricky did you

221
00:11:16,078 --> 00:11:19,008
certainly beyond the scope of this
course but keep in mind those of the

222
00:11:19,008 --> 00:11:22,076
questions that we entertain as positions
as for reading the literature

223
00:11:22,076 --> 00:11:26,059
now one of the outcomes that was was
mentioned was improvement in blood sugar

224
00:11:26,059 --> 00:11:32,038
so first of all how would we measure
that

225
00:11:32,038 --> 00:11:34,329
but voz votes

226
00:11:34,329 --> 00:11:37,309
okay so you could be looking at that's
the blood sugar which have been one

227
00:11:37,309 --> 00:11:40,075
marker of diabetes hemoglobin a one c
which alert next year

228
00:11:40,075 --> 00:11:45,013
is a eleven for a test that we get that
it looks at patients long-term control

229
00:11:45,013 --> 00:11:47,959
our blood sugar at least medium control
over the past three months

230
00:11:47,959 --> 00:11:49,048
so that be a good outcome

231
00:11:49,048 --> 00:11:53,017
to specify so you could get that level
of specificity and you might find

232
00:11:53,017 --> 00:11:57,369
studies that look at just after larger
verses does that look at a one c and you

233
00:11:57,369 --> 00:11:59,066
would have to decide which ones

234
00:11:59,066 --> 00:12:02,068
for me in my patient now would be
important consideration

235
00:12:02,068 --> 00:12:05,072
any other types of outcomes you guys
looked at

236
00:12:05,072 --> 00:12:15,027
or anyone specified besides blood sugar
improvement

237
00:12:15,027 --> 00:12:18,047
basil side effects might be another
outcome that you would look at what sort

238
00:12:18,047 --> 00:12:21,089
of side effects might be worth we'd be
worried about a few

239
00:12:21,089 --> 00:12:24,075
if you know any

240
00:12:24,075 --> 00:12:27,082
so one that i might be worried about is
would i be dropping this patient's blood

241
00:12:27,082 --> 00:12:29,059
sugar too low

242
00:12:29,059 --> 00:12:31,032
to the point that they have hypoglycemic
events

243
00:12:31,032 --> 00:12:32,097
so that would be something to be
thinking about

244
00:12:32,097 --> 00:12:37,031
but absolutely remember this is a
therapeutic question that your asking

245
00:12:37,031 --> 00:12:40,096
and as if they're peter question there
are unintended or sometimes

246
00:12:40,096 --> 00:12:44,419
uh... known side effects of the
different genes that we

247
00:12:44,419 --> 00:12:47,026
that we use and so looking at the
adverse events

248
00:12:47,026 --> 00:12:49,011
would be another important outcome

249
00:12:49,011 --> 00:12:52,009
so keep in mind this is just an exercise
but to wall

250
00:12:52,009 --> 00:12:55,035
to get us to where we dot where we need
to go so that when we look at the

251
00:12:55,035 --> 00:12:56,000
literature

252
00:12:56,000 --> 00:12:57,499
we know what we're looking at

253
00:12:57,499 --> 00:12:59,074
that is the point of the foreground
question

254
00:12:59,074 --> 00:13:01,007
now this is up there

255
00:13:01,007 --> 00:13:03,949
foreground question before i questions
about their feet

256
00:13:03,949 --> 00:13:07,459
later on in this lecture really talking
about or run questions

257
00:13:07,459 --> 00:13:09,061
as it pertains to diagnostic tests

258
00:13:09,061 --> 00:13:12,369
again to get distinct types of questions

259
00:13:12,369 --> 00:13:16,979
but both equally important here a couple
of examples that we that were uh... that

260
00:13:16,979 --> 00:13:21,029
would be reasonable i think you guys
came in kimba up with these in tight to

261
00:13:21,029 --> 00:13:23,098
die but if that was one thing we didn't
talk about the fact that this woman

262
00:13:23,098 --> 00:13:25,089
is a tight to diabetic

263
00:13:25,089 --> 00:13:28,061
she may be insulin requiring more
insulin

264
00:13:28,061 --> 00:13:32,001
resist uh... you know that we talk about
that one person so i can fight one being

265
00:13:32,001 --> 00:13:33,007
autoimmune

266
00:13:33,007 --> 00:13:36,019
more likely to happen upon early onset

267
00:13:36,019 --> 00:13:37,011
tight too

268
00:13:37,011 --> 00:13:39,097
uh... not necessarily requiring insulin

269
00:13:39,097 --> 00:13:42,589
uh... and so you might want to
distinguish that studies that you're

270
00:13:42,589 --> 00:13:43,066
looking at

271
00:13:43,066 --> 00:13:46,084
but then there's a question is metformin
good write better than the bread alone

272
00:13:46,084 --> 00:13:49,075
in lower bucks ordered that was
something that you guys came up with and

273
00:13:49,075 --> 00:13:52,076
here's the side-effect question among
women with type two diabetes

274
00:13:52,076 --> 00:13:56,017
are there more instances of low blood
sugar of insufficient on both metformin

275
00:13:56,017 --> 00:13:57,066
it would be right

276
00:13:57,066 --> 00:13:59,036
when compared with we'll be right along

277
00:13:59,036 --> 00:14:02,068
so that you guys came up with this
fairly straightforward exercised but

278
00:14:02,068 --> 00:14:06,036
keep in mind level of specificity is
important because you're gonna be faced

279
00:14:06,036 --> 00:14:08,011
with a ton of different studies

280
00:14:08,011 --> 00:14:10,087
you're gonna have to work through to
figure out which are the ones that are

281
00:14:10,087 --> 00:14:14,096
most relevant tumi and the patient that
you're working with what are the

282
00:14:14,096 --> 00:14:17,051
important outcomes to that may be very
different

283
00:14:17,051 --> 00:14:20,057
and the outcomes that you are interested
in and so it's important vehicle to

284
00:14:20,057 --> 00:14:23,053
specify that of prop yes

285
00:14:23,053 --> 00:14:25,379
went

286
00:14:25,379 --> 00:14:27,072
at

287
00:14:27,072 --> 00:14:31,899
so it literature doesn't exist uh...
what do you do that is probably

288
00:14:31,899 --> 00:14:35,032
uh... the hardest question we face as
clinicians

289
00:14:35,032 --> 00:14:38,008
there is a when i'm gonna ask you to i'm
not gonna be able to answer that

290
00:14:38,008 --> 00:14:39,003
completely

291
00:14:39,003 --> 00:14:42,099
but as we build our course over the next
three years what you're going to get a

292
00:14:42,099 --> 00:14:44,008
sense of

293
00:14:44,008 --> 00:14:46,076
is that there is a hierarchy of evidence

294
00:14:46,076 --> 00:14:48,028
meaning that as

295
00:14:48,028 --> 00:14:52,045
certain studies take on certain study
characteristics both in terms of how

296
00:14:52,045 --> 00:14:56,092
they're designed and how well their
implemented the level of evidence that

297
00:14:56,092 --> 00:14:59,086
they provide become stronger or weaker

298
00:14:59,086 --> 00:15:03,028
and so it's not necessarily do i have

299
00:15:03,028 --> 00:15:05,007
is there no studies out there

300
00:15:05,007 --> 00:15:07,098
what are their studies out there that
are less well done and so what do i do

301
00:15:07,098 --> 00:15:08,086
with those

302
00:15:08,086 --> 00:15:10,094
compared to studies that are really well
done

303
00:15:10,094 --> 00:15:14,061
keeping in mind that the studies that
are really well done are actually less

304
00:15:14,061 --> 00:15:15,899
frequently encounter

305
00:15:15,899 --> 00:15:19,079
and those studies that are not so well
done or studies that are

306
00:15:19,079 --> 00:15:21,082
observation as opposed to control
clinical trials

307
00:15:21,082 --> 00:15:24,043
so the answer your question is i don't
have the answer now but that is exactly

308
00:15:24,043 --> 00:15:26,007
going to be the point of the next three
years

309
00:15:26,007 --> 00:15:29,066
what do you do when you're faced with a
quandary we're gonna try to party

310
00:15:29,066 --> 00:15:31,073
conceptual model that will on full

311
00:15:31,073 --> 00:15:35,002
that you'll get more comfortable

312
00:15:35,002 --> 00:15:38,066
there many sources the foreground
questions these are the pics precise

313
00:15:38,066 --> 00:15:40,729
questions if you go to medline four

314
00:15:40,729 --> 00:15:43,091
or that you will go to a practice
guidelines or you'll use evidence-based

315
00:15:43,091 --> 00:15:46,139
databases and all of these sorts of

316
00:15:46,139 --> 00:15:48,008
of uh... of resources will be introduced
to you

317
00:15:48,008 --> 00:15:52,003
as we go through

318
00:15:52,003 --> 00:15:54,081
so building on those questions then

319
00:15:54,081 --> 00:15:58,879
we do need to then figure out what is
the data that we're getting and how do

320
00:15:58,879 --> 00:15:59,093
we interpret

321
00:15:59,093 --> 00:16:03,149
and so as i mentioned therapy types of
questions are

322
00:16:03,149 --> 00:16:04,088
are very important part

323
00:16:04,088 --> 00:16:07,019
of what we do is the nation's they seem
to be

324
00:16:07,019 --> 00:16:10,579
the most natural thing you would assume
positions do which is prescribed

325
00:16:10,579 --> 00:16:11,031
treatment

326
00:16:11,031 --> 00:16:12,088
and figure out whether it's

327
00:16:12,088 --> 00:16:14,043
making a difference or not

328
00:16:14,043 --> 00:16:17,092
however it is not the most fundamental
thing that we do in fact

329
00:16:17,092 --> 00:16:20,007
therapeutic questions are very
sophisticated questions

330
00:16:20,007 --> 00:16:24,239
that we actually don't cover much about
their pete this year

331
00:16:24,239 --> 00:16:27,084
we do it in your second year as you
start tackling pathophysiology

332
00:16:27,084 --> 00:16:29,003
this year

333
00:16:29,003 --> 00:16:31,008
the question we want you to start
thinking about

334
00:16:31,008 --> 00:16:33,072
what is going on

335
00:16:33,072 --> 00:16:39,023
is that you all a g of why what i'm so
the the clinical manifestations

336
00:16:39,023 --> 00:16:40,042
of the disease

337
00:16:40,042 --> 00:16:44,099
and so that really focuses on diagnostic
reasoning and diagnostic test and so

338
00:16:44,099 --> 00:16:49,042
we're gonna spend the rest of our time
today focusing on diagnostic tests

339
00:16:49,042 --> 00:16:52,087
so here are the learning objectives for
the rest of today by the end by the end

340
00:16:52,087 --> 00:16:55,068
of this lecture and honestly by the end
of your small groups tomorrow because

341
00:16:55,068 --> 00:16:58,082
you're gonna have to work through these
concepts in small groups it's gonna be

342
00:16:58,082 --> 00:17:00,031
mainly a superficial

343
00:17:00,031 --> 00:17:02,041
covering today of the concept

344
00:17:02,041 --> 00:17:05,032
and the diving into it with your simon
in small groups are really where the

345
00:17:05,032 --> 00:17:06,066
learnings going to happen

346
00:17:06,066 --> 00:17:08,999
but by the end of this series of
sessions

347
00:17:08,999 --> 00:17:10,006
you should be able to do some

348
00:17:10,006 --> 00:17:12,016
fairly basic diagnostic

349
00:17:12,016 --> 00:17:14,022
diagnostic question formulation

350
00:17:14,022 --> 00:17:17,339
you should be able to define and uh...
calculate

351
00:17:17,339 --> 00:17:20,959
sensitivity specificities and the
predicted values for different

352
00:17:20,959 --> 00:17:24,065
diagnostic test for an introduce that
concept you today and tomorrow

353
00:17:24,065 --> 00:17:27,048
and you should be able to explain how
risk factor

354
00:17:27,048 --> 00:17:30,289
that god can thrive prior probabilities

355
00:17:30,289 --> 00:17:33,669
and how this concept relates to
prevalence

356
00:17:33,669 --> 00:17:37,749
and then finally you should be able to
modify probabilities from test results

357
00:17:37,749 --> 00:17:39,007
through on number of different
mechanisms

358
00:17:39,007 --> 00:17:44,009
we introduce you to the concept obeys
probabilistic reasoning as a way of

359
00:17:44,009 --> 00:17:46,043
modifying probabilities over time

360
00:17:46,043 --> 00:17:47,059
today we're gonna use

361
00:17:47,059 --> 00:17:51,045
to buy two tables which is a of more
straightforward

362
00:17:51,045 --> 00:17:55,027
easy to conceptualize and visualize way
of modifying probabilities

363
00:17:55,027 --> 00:17:58,429
but you'll get more and more practice
with using that keep in mind that it is

364
00:17:58,429 --> 00:18:03,013
just as good as base so these are
presented to you as you should be one

365
00:18:03,013 --> 00:18:07,049
over the other represented the u<u>s</u>
items to put in your toolbox in portland

366
00:18:07,049 --> 00:18:07,057
out

367
00:18:07,057 --> 00:18:09,909
at different points when the need arises

368
00:18:09,909 --> 00:18:13,038
there also other tools that are
available that will introduce to you one

369
00:18:13,038 --> 00:18:14,094
called likelihood ratios

370
00:18:14,094 --> 00:18:16,081
and you'll get a chance to practice
these

371
00:18:16,081 --> 00:18:20,029
in your assignments and in your smokers

372
00:18:20,029 --> 00:18:24,072
so just like we had the odyssey as a
case for introducing you to use

373
00:18:24,072 --> 00:18:29,013
probabilistic reasoning this time really
immerse yourself in a clinical case and

374
00:18:29,013 --> 00:18:31,075
i want you to think about this again
just with uh...

375
00:18:31,075 --> 00:18:35,083
limited amount of knowledge you have
about this condition of this disease

376
00:18:35,083 --> 00:18:37,033
whatever you have this fall

377
00:18:37,033 --> 00:18:40,057
but bring to bear your experience as we
work through this case during the

378
00:18:40,057 --> 00:18:42,009
remaining a bit the remainder of this
like

379
00:18:42,009 --> 00:18:45,044
so the cases is sixty year old man

380
00:18:45,044 --> 00:18:47,059
who does not have heart disease

381
00:18:47,059 --> 00:18:50,799
who presents with sudden onset of
shortness of breath

382
00:18:50,799 --> 00:18:53,002
dismissed is a term that we use

383
00:18:53,002 --> 00:18:56,099
so here is a politically description of
the problem that you can see

384
00:18:56,099 --> 00:19:00,008
yesterday after he flew in from
california the day before

385
00:19:00,008 --> 00:19:03,091
he'll blokes suddenly in the middle of
the night at three in the morning with

386
00:19:03,091 --> 00:19:05,092
sudden shortness of breath

387
00:19:05,092 --> 00:19:08,089
so we woke up gasping for air at three
in the morning

388
00:19:08,089 --> 00:19:10,014
and he tells you

389
00:19:10,014 --> 00:19:12,057
that you ask them one question which is

390
00:19:12,057 --> 00:19:16,082
well was it bad when you were lying down
and that's why you setup or was it worth

391
00:19:16,082 --> 00:19:19,066
when you or is it about the same
regardless of whether you're setting up

392
00:19:19,066 --> 00:19:20,009
ur lying down

393
00:19:20,009 --> 00:19:24,097
because the people maybe was worse than
usual you said you know what

394
00:19:24,097 --> 00:19:26,007
actually is it

395
00:19:26,007 --> 00:19:28,082
any different online down if i'm sitting
up

396
00:19:28,082 --> 00:19:30,003
i'm still

397
00:19:30,003 --> 00:19:33,037
feeling short of breath and it won't be
up in the middle of the night

398
00:19:33,037 --> 00:19:36,022
all right so that is your initial chief
complaint

399
00:19:36,022 --> 00:19:40,023
this is something that you'll get used
to uh... as you do your data uh...

400
00:19:40,023 --> 00:19:43,059
queries from uh... from patients at your
data gathering

401
00:19:43,059 --> 00:19:44,051
from from different

402
00:19:44,051 --> 00:19:46,046
but you being a good clinician

403
00:19:46,046 --> 00:19:49,088
you start asking some follow-up
questions just like a good clinician

404
00:19:49,088 --> 00:19:53,022
uh... or good mccain sort of building on
the mechanic model that we introduce you

405
00:19:53,022 --> 00:19:54,052
to a week ago

406
00:19:54,052 --> 00:19:58,001
so you ask him what other symptoms were
you feeling at the time

407
00:19:58,001 --> 00:20:02,008
now as you get more sophisticated you
will be asking more specific questions

408
00:20:02,008 --> 00:20:02,085
right now

409
00:20:02,085 --> 00:20:05,019
sort of the about what i would expect

410
00:20:05,019 --> 00:20:08,025
and what seems to be able to do what
else we feeling at the time

411
00:20:08,025 --> 00:20:10,084
well he says does not testing

412
00:20:10,084 --> 00:20:15,399
he doesn't have a leg pain he doesn't
notice any swelling of his leg

413
00:20:15,399 --> 00:20:18,899
he says idea just come back from a long
plane ride he flew in from california

414
00:20:18,899 --> 00:20:21,067
solicit was about five hours

415
00:20:21,067 --> 00:20:23,074
nonstop

416
00:20:23,074 --> 00:20:27,066
and he's had no problems like this
before that he knows

417
00:20:27,066 --> 00:20:29,094
this shortness of breath

418
00:20:29,094 --> 00:20:34,001
he takes one aspirin every day and he
does a smoke a pack of cigarettes

419
00:20:34,001 --> 00:20:35,067
everyday

420
00:20:35,067 --> 00:20:38,669
so that's kind of the next phase of
diagnostic

421
00:20:38,669 --> 00:20:41,017
intake

422
00:20:41,017 --> 00:20:45,014
so the question that faces all of us
just like the mechanic faces

423
00:20:45,014 --> 00:20:48,007
is to be able to build a differential
diagnosis you remember me mentioning

424
00:20:48,007 --> 00:20:50,009
well we as clinicians

425
00:20:50,009 --> 00:20:52,045
still differential diagnoses all the
time

426
00:20:52,045 --> 00:20:55,059
and basically differential diagnosis is
a list

427
00:20:55,059 --> 00:20:59,929
of possibilities with associated likely
that's with associated probabilities

428
00:20:59,929 --> 00:21:04,047
so as we mentioned last time if you can
p of a particular condition you'd be

429
00:21:04,047 --> 00:21:06,006
saying that the likelihood that

430
00:21:06,006 --> 00:21:09,001
this particular condition is the reason
for the shortness of breath

431
00:21:09,001 --> 00:21:11,098
is x percent that's how you would write
that down

432
00:21:11,098 --> 00:21:16,169
and what you would do is you place it in
descending order of likelihood and you

433
00:21:16,169 --> 00:21:18,003
would be talking about wine

434
00:21:18,003 --> 00:21:20,059
if you could get this

435
00:21:20,059 --> 00:21:21,799
conceptual approach

436
00:21:21,799 --> 00:21:24,049
jupe all your differential diagnoses

437
00:21:24,049 --> 00:21:27,036
you will do well in medicine because
this is how we talk

438
00:21:27,036 --> 00:21:31,046
now we don't do it necessarily in such
mathematical discrete models

439
00:21:31,046 --> 00:21:34,076
is exactly what we talk when we talk
with another position we like you know

440
00:21:34,076 --> 00:21:35,013
what

441
00:21:35,013 --> 00:21:39,169
i think this patient has colon cancer
it's definitely more likely that he's

442
00:21:39,169 --> 00:21:41,037
got colon cancer than he has hemorrhoids

443
00:21:41,037 --> 00:21:44,049
that's kind of how we speak in barely in
formal settings

444
00:21:44,049 --> 00:21:45,659
when we're discussing

445
00:21:45,659 --> 00:21:48,074
uh... the case uh... a particular
patients case in trying to understand it

446
00:21:48,074 --> 00:21:49,063
yala g

447
00:21:49,063 --> 00:21:52,046
what we're really doing though is that
words generating a differential

448
00:21:52,046 --> 00:21:56,032
diagnosis and it is the regardless of
what field you're going to do

449
00:21:56,032 --> 00:21:58,059
you'll be doing this over and over again

450
00:21:58,059 --> 00:22:01,006
so you get to your first one today

451
00:22:01,006 --> 00:22:02,008
so now what i'd like you to do

452
00:22:02,008 --> 00:22:04,004
is think about

453
00:22:04,004 --> 00:22:08,006
what possibilities may be going on with
this particular time

454
00:22:08,006 --> 00:22:12,088
talk it over with your partner list two
or three things that might be going on

455
00:22:12,088 --> 00:22:18,023
and i will talk about what i think might
be going on

456
00:22:18,023 --> 00:23:17,009
e

457
00:23:17,009 --> 00:23:21,064
okay productive well on the five because
it's probably arctic every different

458
00:23:21,064 --> 00:23:22,059
about yourself

459
00:23:22,059 --> 00:23:24,011
at this stage that you're at

460
00:23:24,011 --> 00:23:25,091
but it's not wrong to try

461
00:23:25,091 --> 00:23:28,007
so let's just hear something you don't
have to give me a probability or

462
00:23:28,007 --> 00:23:29,049
anything like that

463
00:23:29,049 --> 00:23:38,098
just give me some possibilities of what
might be going on

464
00:23:38,098 --> 00:23:42,034
all materialism versus congestive heart
failure okay so we've got pulmonary

465
00:23:42,034 --> 00:23:43,219
embolism

466
00:23:43,219 --> 00:23:45,679
congestive heart failure what else do we
go

467
00:23:45,679 --> 00:23:50,098
sleep apnea okay great other things yeah

468
00:23:50,098 --> 00:23:54,026
guilty gear emphysema while you guys and
he you've gone through medical school

469
00:23:54,026 --> 00:23:57,074
before these are great coverage is a
great differential diagnosis absolutely

470
00:23:57,074 --> 00:24:01,269
ep

471
00:24:01,269 --> 00:24:03,087
events

472
00:24:03,087 --> 00:24:07,083
hotbed i'd i didn't ask him about scuba
diving and whether he had uh...

473
00:24:07,083 --> 00:24:10,038
at whether he had done that but
certainly that would be a follow-up

474
00:24:10,038 --> 00:24:12,055
question that we would act

475
00:24:12,055 --> 00:24:15,027
these are these are great things now
let's peace apart with these things me

476
00:24:15,027 --> 00:24:17,063
first of all what is a pulmonary
embolism

477
00:24:17,063 --> 00:24:20,017
which had pulmonary embolism you know
what it p<u>s</u>

478
00:24:20,017 --> 00:24:40,009
unexplained

479
00:24:40,009 --> 00:24:41,094
so o'clock in the long

480
00:24:41,094 --> 00:24:45,099
the person was sitting in mobile for a
period of time which allows rumbled sis

481
00:24:45,099 --> 00:24:50,029
to develop especially in the lower
extremities which can then migrate up

482
00:24:50,029 --> 00:24:51,088
and gets stuck in the long

483
00:24:51,088 --> 00:24:55,059
you stated that his shortness of breath
with sudden and so you started unpack

484
00:24:55,059 --> 00:24:58,027
the whole concept of rationale and my
thinking that

485
00:24:58,027 --> 00:25:01,023
versus some of the other things because
often times when you get a p<u>e</u> it

486
00:25:01,023 --> 00:25:04,087
suddenly breaks off part of your of the
clock suddenly breaks off and goes into

487
00:25:04,087 --> 00:25:06,022
the pulmonary basketball

488
00:25:06,022 --> 00:25:09,389
now you'll understate you'll start
developing the language around that but

489
00:25:09,389 --> 00:25:13,049
that's a great way to explain that you
also mentioned congestive heart failure

490
00:25:13,049 --> 00:25:15,679
now what is congestive heart

491
00:25:15,679 --> 00:25:18,041
art which on the spot but i was a good
differential i'm coming back into our

492
00:25:18,041 --> 00:25:42,015
world seven you know

493
00:25:42,015 --> 00:25:46,069
all right so congestive heart failure
being basically eight at in enhanced

494
00:25:46,069 --> 00:25:49,014
pulmonary vascular

495
00:25:49,014 --> 00:25:51,047
in the palm area vascular system because

496
00:25:51,047 --> 00:25:53,081
the heart is not able to

497
00:25:53,081 --> 00:25:58,051
nearly as good injection of the blood
through the periphery and so things back

498
00:25:58,051 --> 00:26:01,159
up for a bride of the reasons either
though

499
00:26:01,159 --> 00:26:04,003
orgasm pump is well it's two-step you
got valvular leakage

500
00:26:04,003 --> 00:26:07,095
and it backs up into the pulmonary
vasculature you increase the pressure it

501
00:26:07,095 --> 00:26:12,053
you cause pulmonary edema which gives
you offensive shortness of breath but as

502
00:26:12,053 --> 00:26:15,091
you mentioned oftentimes that'll be
accompanied by peripheral oedema because

503
00:26:15,091 --> 00:26:19,001
of the heart backs up from left
ventricular failure right ventricular

504
00:26:19,001 --> 00:26:19,083
failure

505
00:26:19,083 --> 00:26:20,093
than you actually have

506
00:26:20,093 --> 00:26:22,669
summit denying your lower extremities

507
00:26:22,669 --> 00:26:26,046
she doesn't according to him we haven't
done the examination you so that's the

508
00:26:26,046 --> 00:26:30,012
caveat here but that may be a reasonable
thing to come up with uh... to uh... to

509
00:26:30,012 --> 00:26:33,679
come up with in your differential and
you put it lower because there were some

510
00:26:33,679 --> 00:26:35,909
aspects that weren't necessarily as

511
00:26:35,909 --> 00:26:38,059
consistent with that bag no's' right

512
00:26:38,059 --> 00:26:41,033
so that's a that's a great way to
approach the differential

513
00:26:41,033 --> 00:26:43,001
i would mention obstructive sleep apnea

514
00:26:43,001 --> 00:26:43,929
overhear yet

515
00:26:43,929 --> 00:26:46,073
what's obstructive sleep apnea might
like that that here

516
00:26:46,073 --> 00:26:57,809
e

517
00:26:57,809 --> 00:27:00,085
pacbell now that site so what let me
just uh... unpack what you're saying

518
00:27:00,085 --> 00:27:01,449
there

519
00:27:01,449 --> 00:27:04,049
you're commenting on the fact that this
guy woke up in the middle of the night

520
00:27:04,049 --> 00:27:06,086
with shortness of breath now oftentimes
people who

521
00:27:06,086 --> 00:27:09,059
have obstructive sleep apnea don't
actually wake up

522
00:27:09,059 --> 00:27:12,027
but they have apnea episodes which means
that they

523
00:27:12,027 --> 00:27:13,429
stopped breathing

524
00:27:13,429 --> 00:27:17,036
for a period of time and sometimes i can
cause them to suddenly startle and wake

525
00:27:17,036 --> 00:27:20,005
up they don't necessarily wake up short
of breath but they can't

526
00:27:20,005 --> 00:27:23,065
absolutely until anyone that wakes up in
the middle of the night

527
00:27:23,065 --> 00:27:25,063
i'm certainly thinking about sleep apnea

528
00:27:25,063 --> 00:27:29,369
it's probably one of the most under
diagnosed conditions in this country

529
00:27:29,369 --> 00:27:32,769
i didn't know the reggie white died of
it but he certainly would be pat rescue

530
00:27:32,769 --> 00:27:34,839
uvic because people who have are

531
00:27:34,839 --> 00:27:37,048
uh... and i don't know how it will be c
was but large

532
00:27:37,048 --> 00:27:41,059
body habit is certainly is a risk factor
for obstructive sleep apnea

533
00:27:41,059 --> 00:27:45,429
also can lead to right sided congestive
heart failure so might also be connected

534
00:27:45,429 --> 00:27:47,065
to one of the diagnoses that we heard
early on

535
00:27:47,065 --> 00:27:52,005
so keep in mind that sometimes diagnoses
are completely independent of themselves

536
00:27:52,005 --> 00:27:55,009
revelry talked about independent
independent events

537
00:27:55,009 --> 00:27:58,299
sometimes different items in your
differential are actually related to

538
00:27:58,299 --> 00:28:02,002
other items that you differential so we
have to keep that in mind as well

539
00:28:02,002 --> 00:28:05,009
by legal said feel p<u>d</u> in the back and
now possible emphysema what is that

540
00:28:05,009 --> 00:28:07,078
and why might he be at risk for them

541
00:28:07,078 --> 00:28:28,659
front his

542
00:28:28,659 --> 00:28:29,094
baton so

543
00:28:29,094 --> 00:28:32,098
clearly he's got to look just to
reiterate what you're saying

544
00:28:32,098 --> 00:28:34,088
he's a smoker

545
00:28:34,088 --> 00:28:39,029
long-term smoking can cause destruction
and inflammation to the pulmonary

546
00:28:39,029 --> 00:28:40,008
bronchus tree

547
00:28:40,008 --> 00:28:42,029
andy alveolar

548
00:28:42,029 --> 00:28:45,026
uh... components of it what you learn
about this year and next year

549
00:28:45,026 --> 00:28:49,000
uh... destruction of the albee ally is
typically what we see as a mechanism

550
00:28:49,000 --> 00:28:50,038
towards emphysema

551
00:28:50,038 --> 00:28:55,049
which is one manifestation clinical
manifestation of seo p<u>d</u> and certainly

552
00:28:55,049 --> 00:28:56,065
can impair oxygen

553
00:28:56,065 --> 00:28:59,075
exchange which would make you short of
breath and destiny

554
00:28:59,075 --> 00:29:03,034
and maybe he's in the early stages maybe
this is just his first manifestation of

555
00:29:03,034 --> 00:29:03,799
that

556
00:29:03,799 --> 00:29:06,015
you know he said he has ended for breath
before

557
00:29:06,015 --> 00:29:09,033
but your focusing on his rest

558
00:29:09,033 --> 00:29:10,077
dot keep that in mind

559
00:29:10,077 --> 00:29:14,041
some people were focusing on how he
presented waking up in the middle of the

560
00:29:14,041 --> 00:29:15,029
night

561
00:29:15,029 --> 00:29:17,085
some people are focusing on risk

562
00:29:17,085 --> 00:29:21,004
both are absolutely critical as you get
as you generate your differential

563
00:29:21,004 --> 00:29:21,099
diagnosis

564
00:29:21,099 --> 00:29:22,075
risk

565
00:29:22,075 --> 00:29:27,001
drives the order often of the things in
your differential diagnosis

566
00:29:27,001 --> 00:29:28,559
but how u manifest

567
00:29:28,559 --> 00:29:31,007
also changes the order and what you're
thinking about

568
00:29:31,007 --> 00:29:33,035
in a different likeness

569
00:29:33,035 --> 00:29:35,073
both of the things that we need to walk
in with

570
00:29:35,073 --> 00:29:39,052
and as we think about observational
studies tying this to what doctor grover

571
00:29:39,052 --> 00:29:41,016
was talking about last week

572
00:29:41,016 --> 00:29:44,929
observation als studies give us
information about race

573
00:29:44,929 --> 00:29:47,027
they give us information about risk
factor

574
00:29:47,027 --> 00:29:50,008
that contribute to different clinical
case uh... disorders

575
00:29:50,008 --> 00:29:53,429
so very important to trying title of
this to get and question over here some

576
00:29:53,429 --> 00:29:56,072
yes

577
00:29:56,072 --> 00:30:00,042
back g<u>o</u>p_ d is chronic obstructive
pulmonary disease

578
00:30:00,042 --> 00:30:04,024
it is the long-term manifestations of
tobacco use

579
00:30:04,024 --> 00:30:07,057
it can manifest through either emphysema
where you have destruction of the

580
00:30:07,057 --> 00:30:08,083
alveolar tissue

581
00:30:08,083 --> 00:30:11,003
and impaired oxygen exchange as a result

582
00:30:11,003 --> 00:30:14,179
you can also manifest as what we call
chronic bronchitis where you have a

583
00:30:14,179 --> 00:30:16,000
tremendous amount of inflammation

584
00:30:16,000 --> 00:30:20,047
in the broncos and with mucus production
which can also cause impaired oxygen

585
00:30:20,047 --> 00:30:21,034
i mean

586
00:30:21,034 --> 00:30:22,097
uh... oxygenation

587
00:30:22,097 --> 00:30:25,149
so sorry i didn't identified annual

588
00:30:25,149 --> 00:30:28,559
learn all of these concepts as you move
on

589
00:30:28,559 --> 00:30:31,075
so you're doing a great job building
your first differential diagnosis now

590
00:30:31,075 --> 00:30:33,045
the problem is is i also said

591
00:30:33,045 --> 00:30:36,085
we have to start assigning probabilities
to get to these different

592
00:30:36,085 --> 00:30:40,013
uh... clinical manifestations of just
give you an idea of what my list was

593
00:30:40,013 --> 00:30:41,076
before we get started

594
00:30:41,076 --> 00:30:43,072
that's right

595
00:30:43,072 --> 00:30:45,013
congestive heart failure

596
00:30:45,013 --> 00:30:47,059
and that the amount exacerbate shin

597
00:30:47,059 --> 00:30:49,092
and i also thought about asthma which
could be another

598
00:30:49,092 --> 00:30:53,269
different manifestation that is not
necessarily smoking related

599
00:30:53,269 --> 00:30:56,749
but also uh... can contribute to airway
inflammation

600
00:30:56,749 --> 00:30:59,969
i didn't have obstructive sleep apnea in
my differential that doesn't mean that

601
00:30:59,969 --> 00:31:01,589
it's wrong to put it there

602
00:31:01,589 --> 00:31:05,249
um... many people would and what you'll
find is a different clinicians will

603
00:31:05,249 --> 00:31:09,419
bring their different behind the scenes
to their differential diagnosis

604
00:31:09,419 --> 00:31:12,002
of the question is what do you do when
they're all these behind seas out there

605
00:31:12,002 --> 00:31:17,065
and how do we assign probabilities to
the different uh... clinical

606
00:31:17,065 --> 00:31:19,549
uh... entities in your differential

607
00:31:19,549 --> 00:31:22,789
or sometimes we can do it by a gut
feeling

608
00:31:22,789 --> 00:31:26,098
based on what we know about the disease
based on what we know about the patient

609
00:31:26,098 --> 00:31:29,279
based on what we know about the for
respects

610
00:31:29,279 --> 00:31:32,071
and so here's my gut feeling
differential diagnosis

611
00:31:32,071 --> 00:31:34,096
i put p<u>e</u> at the top

612
00:31:34,096 --> 00:31:36,659
i could see a jeff next

613
00:31:36,659 --> 00:31:40,011
at thirty uh... and i put emphysema
thirteen asthma fourth

614
00:31:40,011 --> 00:31:43,016
and i tried to make it all add up to a
hundred percent so it was nice to meet

615
00:31:43,016 --> 00:31:46,539
so i could forty thirty twenty ten

616
00:31:46,539 --> 00:31:49,046
there is at a right answer you don't
know

617
00:31:49,046 --> 00:31:53,024
that's just my gut feeling but what it
does tell you is i didn't think that

618
00:31:53,024 --> 00:31:57,909
pete was so overwhelmingly likely and i
would put that at seventy percent and

619
00:31:57,909 --> 00:31:59,036
everything else down at the bottom

620
00:31:59,036 --> 00:32:02,006
there may be clinical conditions where
you do that but keep in mind that each

621
00:32:02,006 --> 00:32:04,007
one of these diagnosis

622
00:32:04,007 --> 00:32:05,068
had both its

623
00:32:05,068 --> 00:32:08,038
can uh... consistent features

624
00:32:08,038 --> 00:32:11,058
and something that we're just kind of
atypical

625
00:32:11,058 --> 00:32:14,075
why wouldn't it be a p<u>e</u> well he said
he didn't have a new leads well he'll

626
00:32:14,075 --> 00:32:18,007
appear on a plane ride for five hours
most people don't get a d<u>d</u>t_

627
00:32:18,007 --> 00:32:19,499
well maybe ever

628
00:32:19,499 --> 00:32:20,092
symbol that looks like

629
00:32:20,092 --> 00:32:23,309
y c h f not bad

630
00:32:23,309 --> 00:32:25,054
because there's you know there's some
things that are consistent with a but he

631
00:32:25,054 --> 00:32:27,045
doesn't have flirts from any of you

632
00:32:27,045 --> 00:32:29,075
until their fingers that will sort of
make you head

633
00:32:29,075 --> 00:32:31,092
and these numbers are part of making

634
00:32:31,092 --> 00:32:34,539
are are my manifestation of making

635
00:32:34,539 --> 00:32:37,669
uh... contribute communicating the head

636
00:32:37,669 --> 00:32:40,012
there a couple of other things you can
do with this

637
00:32:40,012 --> 00:32:42,007
so for example remember

638
00:32:42,007 --> 00:32:44,096
you can combine probabilities of
different events

639
00:32:44,096 --> 00:32:49,024
so what is the probability that
shortness of breath is due to be there p

640
00:32:49,024 --> 00:32:51,009
foresee a chap

641
00:32:51,009 --> 00:32:55,094
given these a particular numbers when
you guys think

642
00:32:55,094 --> 00:33:02,149
seventy percent

643
00:33:02,149 --> 00:33:05,669
if the two are mutually independent
events

644
00:33:05,669 --> 00:33:08,046
meaning that they're not dependent on
each other not meaning that if you happy

645
00:33:08,046 --> 00:33:10,659
you are not more likely to get seja

646
00:33:10,659 --> 00:33:11,061
or vice versa

647
00:33:11,061 --> 00:33:14,018
because if there is that overlap remote
from what we understand about the

648
00:33:14,018 --> 00:33:17,058
disease and you can't combine them by
adding so yes the answer to that would

649
00:33:17,058 --> 00:33:21,038
be seventy percent but remember a thing
in mind that provided that both don't

650
00:33:21,038 --> 00:33:22,098
happen simultaneously

651
00:33:22,098 --> 00:33:26,002
just as an intellectual exercise if you
thought that there might be a ten

652
00:33:26,002 --> 00:33:27,062
percent overlap

653
00:33:27,062 --> 00:33:32,088
in the likelihood that you have both p n
c h f bowing out of the same time

654
00:33:32,088 --> 00:33:35,012
meaning that they are dependent and then
sport

655
00:33:35,012 --> 00:33:36,619
that they're both likely

656
00:33:36,619 --> 00:33:39,389
uh... the it's possible that you're
having both of them happen at the same

657
00:33:39,389 --> 00:33:43,002
time then that you could combine the two
by saying what is the likelihood that

658
00:33:43,002 --> 00:33:45,088
you have either p or c h f

659
00:33:45,088 --> 00:33:47,045
but it wouldn't be seventy percent

660
00:33:47,045 --> 00:33:50,071
would actually be sixty percent because
there's also ten percent chance

661
00:33:50,071 --> 00:33:53,004
but both are happy happening
simultaneously

662
00:33:53,004 --> 00:33:56,059
but the good intellectual exercise to go
through again the numbers art as

663
00:33:56,059 --> 00:33:59,399
important as the concept that it goes
down

664
00:33:59,399 --> 00:34:01,005
when but to events for depend

665
00:34:01,005 --> 00:34:03,017
keep in mind that in medicine

666
00:34:03,017 --> 00:34:05,096
their are absolutely independent events

667
00:34:05,096 --> 00:34:08,129
and their absolutely

668
00:34:08,129 --> 00:34:11,909
that will be dependent and has you go
through your blocks and understand the

669
00:34:11,909 --> 00:34:13,789
diseases you'll get an appreciation

670
00:34:13,789 --> 00:34:18,799
berwyn things are determined and when
they read

671
00:34:18,799 --> 00:34:21,095
so basically what we're doing is worth
actually creating

672
00:34:21,095 --> 00:34:23,659
prior probability

673
00:34:23,659 --> 00:34:27,469
before we have done any further down the
track gathering with this patient

674
00:34:27,469 --> 00:34:29,061
re-affirm a couple of questions that we
would ask

675
00:34:29,061 --> 00:34:33,005
well before we do any further exit we
can do the physical exam yet

676
00:34:33,005 --> 00:34:36,031
we didn't do any real specific
questioning within the week testing yet

677
00:34:36,031 --> 00:34:37,369
we're generating

678
00:34:37,369 --> 00:34:41,279
it prior probability remember we did
that with the woman with the b<u>r</u>c_ a

679
00:34:41,279 --> 00:34:43,099
haitian that we were concerned about

680
00:34:43,099 --> 00:34:45,729
we had a prior probability with her
walking in

681
00:34:45,729 --> 00:34:47,369
do when she was twenty years old

682
00:34:47,369 --> 00:34:50,002
well this is a prior probability that's
based on a number of different factors

683
00:34:50,002 --> 00:34:52,789
that i doubt that i mentioned

684
00:34:52,789 --> 00:34:56,013
on the other hand you can actually
generated prior probability

685
00:34:56,013 --> 00:35:00,034
using some tools that are out there is
what don't want to demonstrate obscene

686
00:35:00,034 --> 00:35:03,669
as some of the tools that might be
helpful to you

687
00:35:03,669 --> 00:35:07,082
so why is there are these things called
clinical prediction rules

688
00:35:07,082 --> 00:35:12,009
mechanical production rules are ways of
using the literature and what we know

689
00:35:12,009 --> 00:35:15,026
about the literature estimate s

690
00:35:15,026 --> 00:35:17,659
about particular disease

691
00:35:17,659 --> 00:35:18,709
and

692
00:35:18,709 --> 00:35:23,119
the uh... the way that we did there are
a number of them that are out there

693
00:35:23,119 --> 00:35:26,969
pulmonary embolism is one of those
clinical diseases that actually has a

694
00:35:26,969 --> 00:35:29,579
number of different political
predictions and i want to sort of show

695
00:35:29,579 --> 00:35:30,028
you

696
00:35:30,028 --> 00:35:33,269
what uh... what one uh... looks like

697
00:35:33,269 --> 00:35:36,839
so what you have here to really think
that your slides that you can use as

698
00:35:36,839 --> 00:35:37,043
well

699
00:35:37,043 --> 00:35:39,599
this is mad calc three counts

700
00:35:39,599 --> 00:35:42,959
this is on the uh... you guys have
access to this and uh... they're unknown

701
00:35:42,959 --> 00:35:44,002
bura different uh...

702
00:35:44,002 --> 00:35:47,239
their number of different medical
calculators here

703
00:35:47,239 --> 00:35:50,092
for p what you would do is you would
enter in the day the for the particular

704
00:35:50,092 --> 00:35:51,889
patient

705
00:35:51,889 --> 00:35:57,409
and then it would give you step here in
the lower right hand corner cc

706
00:35:57,409 --> 00:36:00,769
so let's do that for this particular
case

707
00:36:00,769 --> 00:36:02,649
based on what we know right now

708
00:36:02,649 --> 00:36:07,579
based on what we were going out the
sixties right so we put the sixties

709
00:36:07,579 --> 00:36:09,013
we also know that he's made

710
00:36:09,013 --> 00:36:10,609
so we put that

711
00:36:10,609 --> 00:36:14,389
and then you'll see a whole series of
risk factors here

712
00:36:14,389 --> 00:36:18,819
let's say we don't deal with uh... let's
go down and see what he has

713
00:36:18,819 --> 00:36:22,589
we know he's got the acute onset which
means some that's another

714
00:36:22,589 --> 00:36:23,068
word that you learn

715
00:36:23,068 --> 00:36:25,579
sudden onset of this issue

716
00:36:25,579 --> 00:36:26,759
we click on that

717
00:36:26,759 --> 00:36:30,399
notice what's happening to the risk as
we go through this

718
00:36:30,399 --> 00:36:33,889
just being sixty years old and mail

719
00:36:33,889 --> 00:36:36,649
and then adding acute onset of dyspnea

720
00:36:36,649 --> 00:36:39,749
this risk number goes up to fifty
percent

721
00:36:39,749 --> 00:36:42,329
really jumps up there

722
00:36:42,329 --> 00:36:46,023
and if we added that he might have been
immobilized with saying this

723
00:36:46,023 --> 00:36:47,659
let's say he sat

724
00:36:47,659 --> 00:36:48,073
in a plane

725
00:36:48,073 --> 00:36:52,229
completely comatose for five hours
didn't move out what

726
00:36:52,229 --> 00:36:56,419
that would probably qualify as
immobilization

727
00:36:56,419 --> 00:36:58,259
let's say we clicked that

728
00:36:58,259 --> 00:37:02,079
you'll see that his risk of having a
p<u>e</u> with all of this

729
00:37:02,079 --> 00:37:04,279
is now sixty percent

730
00:37:04,279 --> 00:37:07,249
so my gut feeling of forty percent

731
00:37:07,249 --> 00:37:11,839
probably and underestimation now this is
a gut feeling this is based on

732
00:37:11,839 --> 00:37:15,069
spa operational stocks that are out
there and putting them into a

733
00:37:15,069 --> 00:37:16,509
mathematical model

734
00:37:16,509 --> 00:37:19,006
you can get these things for your
handheld device

735
00:37:19,006 --> 00:37:21,097
you can put them on the web a lot of
these are being integrated into the

736
00:37:21,097 --> 00:37:24,005
electronic health record for positions

737
00:37:24,005 --> 00:37:24,989
so that these

738
00:37:24,989 --> 00:37:28,189
guides can be placed right at the point
of care

739
00:37:28,189 --> 00:37:31,319
i'd encourage you to think about these
and try to explore some of these because

740
00:37:31,319 --> 00:37:34,046
they were a number of these for a number
of different conditions out there

741
00:37:34,046 --> 00:37:37,047
but we're gonna return to this as we go
through so right now

742
00:37:37,047 --> 00:37:39,096
we're starting around sixty percent

743
00:37:39,096 --> 00:37:42,049
as our prior probability

744
00:37:42,049 --> 00:37:44,094
but you realize also that there's a
number of questions here that we just

745
00:37:44,094 --> 00:37:48,749
don't know the answer to the right legal
fees at a fever we don't know we know

746
00:37:48,749 --> 00:37:51,014
that he doesn't have a history very
vascular disease

747
00:37:51,014 --> 00:37:54,045
we don't know if he passed out we don't
know if he's actually got one-sided

748
00:37:54,045 --> 00:37:55,049
lights while

749
00:37:55,049 --> 00:37:57,869
so there's more data we need to get

750
00:37:57,869 --> 00:37:59,539
so let's gather

751
00:37:59,539 --> 00:38:05,169
so more date

752
00:38:05,169 --> 00:38:08,059
so here's some more information then i'm
gonna throw at you based on this

753
00:38:08,059 --> 00:38:09,619
particular case

754
00:38:09,619 --> 00:38:13,169
you talk about family history find out
that he actually

755
00:38:13,169 --> 00:38:14,599
has had

756
00:38:14,599 --> 00:38:19,149
he has a family that is that the d<u>d</u>t_
in the past

757
00:38:19,149 --> 00:38:22,699
pretty for it

758
00:38:22,699 --> 00:38:26,063
you do a physical exam on him and you
find a his blood oxygen saturation is

759
00:38:26,063 --> 00:38:28,109
normal on room air

760
00:38:28,109 --> 00:38:30,989
so these oxygen eighty five

761
00:38:30,989 --> 00:38:35,359
checkers respiratory rate at sixteen
that's generally that's a little fast

762
00:38:35,359 --> 00:38:37,099
but it's probably okay but

763
00:38:37,099 --> 00:38:39,017
his pulse rate is a hundred and buy it
now

764
00:38:39,017 --> 00:38:43,839
united now that a hundred five ezell
elevate we would call that eka kartik

765
00:38:43,839 --> 00:38:45,739
so he's technopark

766
00:38:45,739 --> 00:38:49,005
and you examine his loans as you will
learn to do this year and you'll find

767
00:38:49,005 --> 00:38:52,949
when you became his patients' lungs that
he has crackles

768
00:38:52,949 --> 00:38:54,539
n<u>t</u>s<u>b</u>'s

769
00:38:54,539 --> 00:38:56,339
user crackles are sort of

770
00:38:56,339 --> 00:38:57,053
they sound like crackers

771
00:38:57,053 --> 00:38:59,489
we've ever listen to rice crispy

772
00:38:59,489 --> 00:39:02,859
that's what it sounds like a bit sounds
with inspiration you would get crap that

773
00:39:02,859 --> 00:39:06,429
usually indicates that there's some
degree of a team up in the long some

774
00:39:06,429 --> 00:39:10,007
degree of swelling in the long and as
the albee a liar trying to expand

775
00:39:10,007 --> 00:39:12,949
they pop open up a very easy way but
enough

776
00:39:12,949 --> 00:39:15,089
tough way because there's a lot of
surface tension at each of you

777
00:39:15,089 --> 00:39:19,119
level because of the fluid in the
interstitial space

778
00:39:19,119 --> 00:39:23,649
he's also got leases leases are
indications of airway obstruction small

779
00:39:23,649 --> 00:39:26,189
airways obstruction in the long

780
00:39:26,189 --> 00:39:29,095
but you'll also notice he doesn't have a
problem which means that he doesn't have

781
00:39:29,095 --> 00:39:33,339
this sort of uh... inflammation in the
pleural space which will learn about

782
00:39:33,339 --> 00:39:36,015
and he doesn't have evidence of
consolidation consolidation would give

783
00:39:36,015 --> 00:39:39,039
you some clues that he might have an emo

784
00:39:39,039 --> 00:39:41,589
we don't have either of those

785
00:39:41,589 --> 00:39:44,449
but you also examine is like and you
find that even though he didn't think it

786
00:39:44,449 --> 00:39:47,569
was a swollen it absolutely is well

787
00:39:47,569 --> 00:39:49,869
and you feel of any

788
00:39:49,869 --> 00:39:50,081
below his knee

789
00:39:50,081 --> 00:39:54,002
most of the time we should be able to
feel the danes attorney but if they're

790
00:39:54,002 --> 00:39:56,013
inflamed possibly because of a clock

791
00:39:56,013 --> 00:39:58,439
you might feel below the knee

792
00:39:58,439 --> 00:40:01,929
you get a chest x-ray that's normal

793
00:40:01,929 --> 00:40:05,088
and you get the cagey in its shows that
his heart's going fast but nothing's

794
00:40:05,088 --> 00:40:08,269
besides that

795
00:40:08,269 --> 00:40:10,869
so now what we do is we go back

796
00:40:10,869 --> 00:40:14,489
to the clinical prediction

797
00:40:14,489 --> 00:40:17,094
calculator and cd about entering in this
data

798
00:40:17,094 --> 00:40:22,169
so the additional data that will get

799
00:40:22,169 --> 00:40:23,089
he not only is uh...

800
00:40:23,089 --> 00:40:27,023
sixty years old and mailing it to keep
this thing out and let's say he's

801
00:40:27,023 --> 00:40:29,169
immobilized he was a mobile as

802
00:40:29,169 --> 00:40:34,999
we now find that he's gotten lateral
excellent

803
00:40:34,999 --> 00:40:37,609
but that he also has leases

804
00:40:37,609 --> 00:40:40,609
contracts

805
00:40:40,609 --> 00:40:44,489
no notice what happens to pay attention
to the number as i enter the zip

806
00:40:44,489 --> 00:40:48,038
i started out with sixty percent by
aditi lateral leg swelling what we're

807
00:40:48,038 --> 00:40:50,589
getting really close for x seventy five
percent

808
00:40:50,589 --> 00:40:52,719
but this person's that p

809
00:40:52,719 --> 00:40:53,095
upholding a bit

810
00:40:53,095 --> 00:40:57,059
remember we're talking about as long as
even though

811
00:40:57,059 --> 00:40:58,499
the race

812
00:40:58,499 --> 00:40:59,529
his lead

813
00:40:59,529 --> 00:41:02,009
because if you've got to cut your leg
you're more likely to throw that but we

814
00:41:02,009 --> 00:41:05,026
have a pulmonary embolism those two are
not

815
00:41:05,026 --> 00:41:06,619
independent features

816
00:41:06,619 --> 00:41:08,769
those who are dependent effects

817
00:41:08,769 --> 00:41:12,269
so it dries it up to seven six percent
but knows what happened when i clicked

818
00:41:12,269 --> 00:41:14,469
on visas and practice

819
00:41:14,469 --> 00:41:18,269
that number within seventy five percent
of the thirty five percent

820
00:41:18,269 --> 00:41:19,919
so what in your mind

821
00:41:19,919 --> 00:41:21,839
must you be thinking

822
00:41:21,839 --> 00:41:24,099
the presents of crackles and we use is
actually make

823
00:41:24,099 --> 00:41:28,219
pulmonary embolism last like

824
00:41:28,219 --> 00:41:32,559
in fact pulmonary embolism the number
one clinical finding in the long for p

825
00:41:32,559 --> 00:41:33,729
is nothing

826
00:41:33,729 --> 00:41:36,409
subtotal e normal pulmonary exam

827
00:41:36,409 --> 00:41:38,889
just because you have a normal palm
trees and doesn't mean you don't have a

828
00:41:38,889 --> 00:41:40,239
disease

829
00:41:40,239 --> 00:41:42,066
as an important consideration but keep
in mind that this is a way of

830
00:41:42,066 --> 00:41:43,058
quantifying

831
00:41:43,058 --> 00:41:44,709
how much

832
00:41:44,709 --> 00:41:49,013
dropped there is so we ever did all this
data and we're now at around thirty five

833
00:41:49,013 --> 00:41:50,449
percent

834
00:41:50,449 --> 00:41:52,319
so turns out i was about

835
00:41:52,319 --> 00:42:06,169
or a percent was pretty close to thirty
five pst

836
00:42:06,169 --> 00:42:10,047
there are interactional terms that are
built into the mathematical model here

837
00:42:10,047 --> 00:42:13,579
so if you look above the rest

838
00:42:13,579 --> 00:42:18,159
and sold those interactions are built
into how he calculates the factor some

839
00:42:18,159 --> 00:42:20,809
which then translates to what the risks

840
00:42:20,809 --> 00:42:23,093
so yes there are interaction terms
between these things

841
00:42:23,093 --> 00:42:26,629
and it's calc it's all done in the
background

842
00:42:26,629 --> 00:42:28,799
clinician you know i'm not gonna do that

843
00:42:28,799 --> 00:42:31,669
and i'm certainly not to be able to look
at a study be able to know how to do

844
00:42:31,669 --> 00:42:34,329
that that's why these calculators to be
very helpful

845
00:42:34,329 --> 00:42:37,109
it'll give you an idea are we weigh off

846
00:42:37,109 --> 00:42:39,719
or are we about right is this guy is

847
00:42:39,719 --> 00:42:42,096
was my initial gut feeling over on
target yeah

848
00:42:42,096 --> 00:42:45,839
was kind of on target even when we did
more data gathering

849
00:42:45,839 --> 00:42:47,016
but you also get a sense

850
00:42:47,016 --> 00:42:50,066
uh... why how different features
increase and decrease the likelihood

851
00:42:50,066 --> 00:42:59,649
which is a good learning tool

852
00:42:59,649 --> 00:43:02,689
rate

853
00:43:02,689 --> 00:43:05,119
so the question is of why is

854
00:43:05,119 --> 00:43:06,919
smoking and wake nodding here

855
00:43:06,919 --> 00:43:10,529
the answer is is that smoking and wait
for actually not considered risk factors

856
00:43:10,529 --> 00:43:12,679
for p

857
00:43:12,679 --> 00:43:15,769
when they've looked at these studies
what you might think of boy there smoker

858
00:43:15,769 --> 00:43:17,299
they're more likely to have a clock

859
00:43:17,299 --> 00:43:19,059
into israel

860
00:43:19,059 --> 00:43:21,269
just because you're a smoker doesn't
mean that you're more likely to have a

861
00:43:21,269 --> 00:43:22,309
p<u>e</u>

862
00:43:22,309 --> 00:43:25,039
now certain smokers do carry increase
from body chris

863
00:43:25,039 --> 00:43:28,069
if you're a young woman who smoking on
or contraceptives

864
00:43:28,069 --> 00:43:32,629
you already higher risk of developing a
lower extremity d<u>d</u>t_

865
00:43:32,629 --> 00:43:33,819
at is clear

866
00:43:33,819 --> 00:43:36,829
but that's not necessarily what we're
talking about here

867
00:43:36,829 --> 00:43:39,879
over the lot big picture it doesn't
contribute risk

868
00:43:39,879 --> 00:43:42,709
it also could be because the studies
were done but in this case is because

869
00:43:42,709 --> 00:43:51,659
they're not respect

870
00:43:51,659 --> 00:43:52,509
uh...

871
00:43:52,509 --> 00:43:55,839
so here's the question if you are
thinking that there is a nother

872
00:43:55,839 --> 00:43:59,599
possibility on your differential
diagnosis that is either equally or more

873
00:43:59,599 --> 00:44:04,019
likely does it drive this down the
absentee answers absolutely it does

874
00:44:04,019 --> 00:44:06,043
and there are limits to these clinical
prediction

875
00:44:06,043 --> 00:44:09,052
so this is done in a vacuum their other
clinical prediction rules

876
00:44:09,052 --> 00:44:13,031
where you can actually have a button
that says is an alternative diagnosis

877
00:44:13,031 --> 00:44:17,549
equally or more likely when you do that
people drop your s

878
00:44:17,549 --> 00:44:20,044
because it knows that there may be other
things going up this prediction will

879
00:44:20,044 --> 00:44:25,029
didn't do that

880
00:44:25,029 --> 00:44:29,045
station had a family history of a d<u>d</u>t_
but not a personal history dvd if you're

881
00:44:29,045 --> 00:44:33,009
interested in what that would have done
you could do it if he had a dvd in the

882
00:44:33,009 --> 00:44:34,269
past

883
00:44:34,269 --> 00:44:38,539
it drives up from thirty five to fifty

884
00:44:38,539 --> 00:44:41,979
yet family history of some of his family
with d

885
00:44:41,979 --> 00:44:45,289
all these are great questions but the
most important thing to keep in mind is

886
00:44:45,289 --> 00:44:48,299
you don't just have to go on gut feel

887
00:44:48,299 --> 00:44:51,289
at these clinical prediction rules for
common diseases which are the ones that

888
00:44:51,289 --> 00:44:51,097
are out there

889
00:44:51,097 --> 00:44:53,074
can help you understand

890
00:44:53,074 --> 00:44:58,249
the clinical manifestations of a
particular disease

891
00:44:58,249 --> 00:45:00,859
so what does this have to do with what
we do

892
00:45:00,859 --> 00:45:05,129
well keep in mind we're now

893
00:45:05,129 --> 00:45:06,589
we are now at

894
00:45:06,589 --> 00:45:09,089
um having completed our data gathering
things were based

895
00:45:09,089 --> 00:45:12,058
with the prior probability of about
thirty five percent

896
00:45:12,058 --> 00:45:14,949
at the station is happy

897
00:45:14,949 --> 00:45:16,009
and so what we need to do you think
about

898
00:45:16,009 --> 00:45:18,819
do we need to get a test

899
00:45:18,819 --> 00:45:21,289
because the question that should be
going through your mind is the thirty

900
00:45:21,289 --> 00:45:25,379
five percent high enough at allstate
yahoo dot abt and got a pulmonary

901
00:45:25,379 --> 00:45:26,016
embolism

902
00:45:26,016 --> 00:45:28,089
we're gonna treat you as such

903
00:45:28,089 --> 00:45:31,149
hopefully thirty five percent is too low
for even you

904
00:45:31,149 --> 00:45:34,529
to say boy i don't think that i would
point to treat based on that certainly

905
00:45:34,529 --> 00:45:39,499
would be low for most of the nation's we
need to probably get some sort of text

906
00:45:39,499 --> 00:45:44,489
so what this is a how those bridges over
into diagnostic test

907
00:45:44,489 --> 00:45:47,489
so here is the question what we do with
this number

908
00:45:47,489 --> 00:45:51,249
well if there was a test that existed
that could rule in pulmonary embolism as

909
00:45:51,249 --> 00:45:52,022
the diagnosis

910
00:45:52,022 --> 00:45:54,008
with a hundred percent sense certainty

911
00:45:54,008 --> 00:46:00,529
we would be saying that probability of
this of a patient having a p

912
00:46:00,529 --> 00:46:01,021
due to the

913
00:46:01,021 --> 00:46:02,074
at the test is positive

914
00:46:02,074 --> 00:46:05,619
is a hundred percent

915
00:46:05,619 --> 00:46:09,269
and the question i would ask you is what
is the stressful

916
00:46:09,269 --> 00:46:13,239
what we call this test the boot stain

917
00:46:13,239 --> 00:46:18,289
the gold standard generally exist for
more most conditions where they're is

918
00:46:18,289 --> 00:46:22,099
where works for the past week after the
finding of the best will stand at the

919
00:46:22,099 --> 00:46:23,249
top

920
00:46:23,249 --> 00:46:25,013
uh... it may not be the best test

921
00:46:25,013 --> 00:46:26,036
that we can envision

922
00:46:26,036 --> 00:46:27,069
but it's the best test

923
00:46:27,069 --> 00:46:32,229
that is available

924
00:46:32,229 --> 00:46:35,499
and the question that i would ask is if
you use the gold standard tests and you

925
00:46:35,499 --> 00:46:37,859
found it

926
00:46:37,859 --> 00:46:39,002
the test was positive

927
00:46:39,002 --> 00:46:42,095
is the probability of an alternative
diagnosis remember that a test test

928
00:46:42,095 --> 00:46:46,339
that's a gold standard is only the gold
standard or particular diagnosis

929
00:46:46,339 --> 00:46:48,509
let's say there's another diagnosis

930
00:46:48,509 --> 00:46:49,719
that you're interested in

931
00:46:49,719 --> 00:46:50,869
is it zero

932
00:46:50,869 --> 00:46:52,028
if the test is positive

933
00:46:52,028 --> 00:46:53,043
the answer is no

934
00:46:53,043 --> 00:46:54,279
because

935
00:46:54,279 --> 00:46:56,043
sometimes you have two things going on

936
00:46:56,043 --> 00:46:58,249
sometimes there are vents

937
00:46:58,249 --> 00:47:00,999
that are related to each other dependent
on each other

938
00:47:00,999 --> 00:47:02,071
for sometimes you just have bad luck

939
00:47:02,071 --> 00:47:03,639
as a patient

940
00:47:03,639 --> 00:47:06,619
and you have both pulmonary embolism and
c<u>h</u>a_

941
00:47:06,619 --> 00:47:08,089
but the most important to keep thing to
keep in mind

942
00:47:08,089 --> 00:47:12,279
is that we are always looking to see
what the gold standard is

943
00:47:12,279 --> 00:47:16,459
but we can't always used to go see

944
00:47:16,459 --> 00:47:19,789
so what is that not stick testing people
but not the testing

945
00:47:19,789 --> 00:47:23,043
the the goal of diagnostic testing is to
help us modify probabilities

946
00:47:23,043 --> 00:47:24,008
we talked about how

947
00:47:24,008 --> 00:47:29,021
we modify probabilities based on history
taking physical exam other simple tests

948
00:47:29,021 --> 00:47:32,015
complex s like the ones we're gonna talk
about

949
00:47:32,015 --> 00:47:34,629
will help modify probabilities as well

950
00:47:34,629 --> 00:47:36,129
but they cost a lot of money

951
00:47:36,129 --> 00:47:39,016
and so we need to approach argues a
diagnostic tests

952
00:47:39,016 --> 00:47:42,269
judicious

953
00:47:42,269 --> 00:47:45,069
so in order to understand what we're
looking for work in a study about

954
00:47:45,069 --> 00:47:48,119
diagnostic test we need to understand

955
00:47:48,119 --> 00:47:53,999
how people related items to test

956
00:47:53,999 --> 00:47:56,049
really does relate instead of

957
00:47:56,049 --> 00:47:57,549
the patient

958
00:47:57,549 --> 00:47:59,092
uh... population were interested in

959
00:47:59,092 --> 00:48:02,049
what we're really trying to use the
following

960
00:48:02,049 --> 00:48:05,169
a disease state

961
00:48:05,169 --> 00:48:07,799
what is the disease that we're trying to
diagnose

962
00:48:07,799 --> 00:48:11,109
in this particular case if ur interested
in another test to use

963
00:48:11,109 --> 00:48:14,389
it would be the disease state would be a
pulmonary embolism

964
00:48:14,389 --> 00:48:15,579
intervention

965
00:48:15,579 --> 00:48:19,809
would actually be the test itself so
what tester we interested in his room

966
00:48:19,809 --> 00:48:22,279
looking through the literature

967
00:48:22,279 --> 00:48:25,999
the comparison group is not another
therapy but it was in the therapeutic

968
00:48:25,999 --> 00:48:26,077
questions

969
00:48:26,077 --> 00:48:28,749
it's the gold standard

970
00:48:28,749 --> 00:48:30,049
so you're trying to compare

971
00:48:30,049 --> 00:48:32,099
a test of interest

972
00:48:32,099 --> 00:48:34,839
against what is the best test that's out
there

973
00:48:34,839 --> 00:48:37,459
the problem with the best test that's
out there is that it's frequently

974
00:48:37,459 --> 00:48:38,032
infeasible

975
00:48:38,032 --> 00:48:41,032
sometimes dangerous even though it's the
best s so we're looking for an

976
00:48:41,032 --> 00:48:44,054
alternative test that we can use i can
help us with our page so that those

977
00:48:44,054 --> 00:48:46,279
favoritism

978
00:48:46,279 --> 00:48:49,879
and then the outcome of interest that
were interested in is the performance of

979
00:48:49,879 --> 00:48:51,149
the text

980
00:48:51,149 --> 00:48:53,879
that's the fundamental

981
00:48:53,879 --> 00:48:55,359
and you will be able to

982
00:48:55,359 --> 00:48:56,018
do this

983
00:48:56,018 --> 00:48:59,035
over and over again as you're looking at
different studies and we've this is part

984
00:48:59,035 --> 00:49:00,289
of the assignment

985
00:49:00,289 --> 00:49:02,139
for two more

986
00:49:02,139 --> 00:49:04,459
so let's practice

987
00:49:04,459 --> 00:49:07,689
as we've seen the sixty location without
heart disease is presenting with some

988
00:49:07,689 --> 00:49:09,199
nonsense shortness of breath

989
00:49:09,199 --> 00:49:11,229
we're considering a p

990
00:49:11,229 --> 00:49:14,489
that would be our disease or our p

991
00:49:14,489 --> 00:49:19,269
protest and ask us to consider is a test
collabera profusion scheme

992
00:49:19,269 --> 00:49:21,024
cowbell asian perfusion scan

993
00:49:21,024 --> 00:49:23,939
is something that's been around for a
long time

994
00:49:23,939 --> 00:49:25,589
it basically

995
00:49:25,589 --> 00:49:28,027
in the test a patient in hale's

996
00:49:28,027 --> 00:49:31,899
or radio nuclei partner

997
00:49:31,899 --> 00:49:36,629
and we see where that radio nuclei
particle goals

998
00:49:36,629 --> 00:49:40,239
and in addition the patient gets
injected with that same radio nuclear

999
00:49:40,239 --> 00:49:41,139
particle

1000
00:49:41,139 --> 00:49:43,959
and we see based on the blood flow

1001
00:49:43,959 --> 00:49:45,249
that particle goes

1002
00:49:45,249 --> 00:49:46,769
we take pictures

1003
00:49:46,769 --> 00:49:49,849
simplistic explanation but i thought you
really need to know at this point

1004
00:49:49,849 --> 00:49:51,849
and what we're looking for is

1005
00:49:51,849 --> 00:49:54,029
where does the air go

1006
00:49:54,029 --> 00:49:56,549
that blood doesn't go

1007
00:49:56,549 --> 00:49:59,489
but that there's a place where the air
goes that the blood doesn't go that

1008
00:49:59,489 --> 00:50:02,669
would likely be where o'clock would be

1009
00:50:02,669 --> 00:50:04,399
api

1010
00:50:04,399 --> 00:50:07,599
but that's what happens is that the
clock obstructs blood flow to that

1011
00:50:07,599 --> 00:50:10,219
particular place

1012
00:50:10,219 --> 00:50:12,549
now the gold standard

1013
00:50:12,549 --> 00:50:16,489
four diagnosis of a pulmonary embolism
something we call pulmonary and

1014
00:50:16,489 --> 00:50:17,379
geography

1015
00:50:17,379 --> 00:50:20,739
which is where you were actually
injecting died and watching where the

1016
00:50:20,739 --> 00:50:22,089
blood blow goes

1017
00:50:22,089 --> 00:50:24,069
you see a picture of a b q scan on the
top there

1018
00:50:24,069 --> 00:50:28,939
on the bottom is a very grainy picture
of a pulmonary angiogram

1019
00:50:28,939 --> 00:50:31,409
just keep in mind that an angiogram

1020
00:50:31,409 --> 00:50:33,509
more costly

1021
00:50:33,509 --> 00:50:37,379
slightly more dangerous

1022
00:50:37,379 --> 00:50:38,949
the gold standard

1023
00:50:38,949 --> 00:50:42,539
but we wouldn't because it's costly and
more dangerous we wouldn't offered to

1024
00:50:42,539 --> 00:50:43,819
all patients

1025
00:50:43,819 --> 00:50:44,819
because if we did that

1026
00:50:44,819 --> 00:50:48,027
the risk that we would in anyone who we
suspect has a p

1027
00:50:48,027 --> 00:50:51,013
the amount of complications and cost
that we would entail

1028
00:50:51,013 --> 00:50:53,009
would be mass

1029
00:50:53,009 --> 00:50:56,011
that's what we're looking to see is is
of the few scan which is actually

1030
00:50:56,011 --> 00:50:58,609
fairly

1031
00:50:58,609 --> 00:51:00,539
really fairly

1032
00:51:00,539 --> 00:51:02,349
at not terribly dangerous

1033
00:51:02,349 --> 00:51:05,039
whether that would be good enough
compared to the gold standard for many

1034
00:51:05,039 --> 00:51:07,009
of the geography

1035
00:51:07,009 --> 00:51:10,229
what were interested in is diagnostic
performance

1036
00:51:10,229 --> 00:51:16,709
so that is the pico recognize the test

1037
00:51:16,709 --> 00:51:20,499
but before thinking about it became
scandal then elation perfusion scamper

1038
00:51:20,499 --> 00:51:23,099
first question we have to ask

1039
00:51:23,099 --> 00:51:26,299
kena beat you scan actually even be used

1040
00:51:26,299 --> 00:51:28,779
now you will be asking this question as
a clinician

1041
00:51:28,779 --> 00:51:31,039
but before you can even go to market

1042
00:51:31,039 --> 00:51:32,033
as a possible test

1043
00:51:32,033 --> 00:51:35,041
there's some fundamental questions about
a diagnostic test

1044
00:51:35,041 --> 00:51:38,599
that require some definitions that you
should be aware

1045
00:51:38,599 --> 00:51:42,299
and they thought this on to concerts
accuracy and precision in order for a

1046
00:51:42,299 --> 00:51:43,084
test to be used

1047
00:51:43,084 --> 00:51:47,579
in the literature and study for possible
use it needs to be accurate

1048
00:51:47,579 --> 00:51:50,399
and it needs to be precise or whining
about it

1049
00:51:50,399 --> 00:51:53,054
what accuracy means at the results of
the test

1050
00:51:53,054 --> 00:51:57,209
corresponds consistently with from
result

1051
00:51:57,209 --> 00:52:00,839
not going to result in terms of
diagnosing the disease

1052
00:52:00,839 --> 00:52:02,519
but the correct about

1053
00:52:02,519 --> 00:52:05,619
meaning that it'd be q skin if i object

1054
00:52:05,619 --> 00:52:08,709
the radio nuclei and i say it goes to
the long

1055
00:52:08,709 --> 00:52:10,959
if you go to the law

1056
00:52:10,959 --> 00:52:15,029
and if i inhale the radio nuclei and i
say he should be inhaled into the

1057
00:52:15,029 --> 00:52:16,569
alveolar space

1058
00:52:16,569 --> 00:52:21,039
it should actually be inhaled into the
alveolar sticks

1059
00:52:21,039 --> 00:52:21,729
fundamental

1060
00:52:21,729 --> 00:52:25,219
but keep in mind that there is a clone
of work that happens

1061
00:52:25,219 --> 00:52:28,619
prior to attest going to study

1062
00:52:28,619 --> 00:52:31,229
that requires this to happen

1063
00:52:31,229 --> 00:52:33,839
and there's a lot of science behind us

1064
00:52:33,839 --> 00:52:35,071
so needs to be accurate enemies

1065
00:52:35,071 --> 00:52:39,056
besides we're learning about the size
twelve decision means that if you do

1066
00:52:39,056 --> 00:52:43,309
with over and over again on the same
patient you'll get the same result

1067
00:52:43,309 --> 00:52:45,479
with a reliable test

1068
00:52:45,479 --> 00:52:50,229
the repeated values on the same sample
resume results in the same down

1069
00:52:50,229 --> 00:52:53,529
so in the same patient you do it once
you do it again five minutes later you

1070
00:52:53,529 --> 00:52:54,066
you five minutes later

1071
00:52:54,066 --> 00:52:56,739
missing uh... results actually happened

1072
00:52:56,739 --> 00:52:58,929
that's the preciseness

1073
00:52:58,929 --> 00:53:00,489
you need to have both

1074
00:53:00,489 --> 00:53:02,739
they're actually three different

1075
00:53:02,739 --> 00:53:04,609
possibilities that tend to happen

1076
00:53:04,609 --> 00:53:05,909
when early

1077
00:53:05,909 --> 00:53:09,109
phase studies are done and diagnostic
tests

1078
00:53:09,109 --> 00:53:10,051
the first is the one that you want

1079
00:53:10,051 --> 00:53:13,041
want to be highly accurate and highly
precise pointed out that you're good to

1080
00:53:13,041 --> 00:53:13,091
go

1081
00:53:13,091 --> 00:53:16,839
ready to go to step two and study its
characteristics

1082
00:53:16,839 --> 00:53:17,989
however

1083
00:53:17,989 --> 00:53:20,359
you can have something very precise

1084
00:53:20,359 --> 00:53:22,699
but be completely inaccurate

1085
00:53:22,699 --> 00:53:25,709
that's what's represented conceptually
by the bulls on where you have a lot of

1086
00:53:25,709 --> 00:53:28,017
different numbers there clustering all
around the same area

1087
00:53:28,017 --> 00:53:31,989
but it's actually not doing what you
think it's doing

1088
00:53:31,989 --> 00:53:34,149
and then there is sometimes when you
have

1089
00:53:34,149 --> 00:53:37,589
reasonable accuracy it's all clustered
around the bulls eye

1090
00:53:37,589 --> 00:53:38,929
but low precision

1091
00:53:38,929 --> 00:53:40,529
their hat you get different

1092
00:53:40,529 --> 00:53:42,839
answers each time you do it

1093
00:53:42,839 --> 00:53:45,039
so what do you do in these different
situations

1094
00:53:45,039 --> 00:53:48,459
well the first into a single one step to
your butt

1095
00:53:48,459 --> 00:53:51,249
the second one you gotta think about
calibration

1096
00:53:51,249 --> 00:53:56,609
and you need to reset or maybe you need
to relook at the reagents veteran vault

1097
00:53:56,609 --> 00:53:59,179
at a particular test itself

1098
00:53:59,179 --> 00:54:02,629
in the last one unfortunately you gotta
start over

1099
00:54:02,629 --> 00:54:06,279
if you've got a bunch of if you're a
test is not precise how usable could

1100
00:54:06,279 --> 00:54:07,559
actually be

1101
00:54:07,559 --> 00:54:10,029
you have to actually get the precision
death

1102
00:54:10,029 --> 00:54:12,067
again this may seem fundamental in
foundational

1103
00:54:12,067 --> 00:54:16,489
but there are so many things that don't
make it to market for even testing

1104
00:54:16,489 --> 00:54:18,449
because they don't meet these criteria

1105
00:54:18,449 --> 00:54:21,529
important for you to keep him

1106
00:54:21,529 --> 00:54:25,749
once you make it past that first phase
then you can decide

1107
00:54:25,749 --> 00:54:30,439
diagnostic performance it what the
diagnostic performances the o of the

1108
00:54:30,439 --> 00:54:32,969
pico for diagnostic tests

1109
00:54:32,969 --> 00:54:34,022
and so fundamentally

1110
00:54:34,022 --> 00:54:37,079
i would ask you to think about two
things

1111
00:54:37,079 --> 00:54:41,059
any good diagnostic study does this

1112
00:54:41,059 --> 00:54:43,769
they take a well-defined group of people

1113
00:54:43,769 --> 00:54:46,679
who are at risk for a particular
condition

1114
00:54:46,679 --> 00:54:49,099
a whole population of them and they
expose them to

1115
00:54:49,099 --> 00:54:52,159
the experimental tests

1116
00:54:52,159 --> 00:54:54,969
and the gold st

1117
00:54:54,969 --> 00:54:57,699
everyone in the study needs to have both

1118
00:54:57,699 --> 00:55:01,139
and if you compare the test results

1119
00:55:01,139 --> 00:55:02,379
experimental tests

1120
00:55:02,379 --> 00:55:04,679
and the gold standard

1121
00:55:04,679 --> 00:55:07,879
keep in mind you don't want that patient
population to be

1122
00:55:07,879 --> 00:55:11,089
everyone having the disease a hunter
percent of them having the disease

1123
00:55:11,089 --> 00:55:12,051
you need to have a fair number

1124
00:55:12,051 --> 00:55:15,003
of people who don't have the disease in
order to test

1125
00:55:15,003 --> 00:55:16,959
the test characteristics

1126
00:55:16,959 --> 00:55:20,079
well that's the fundamental premise of
any good diagnostic study and you'll be

1127
00:55:20,079 --> 00:55:22,629
able to recognize he's

1128
00:55:22,629 --> 00:55:26,439
what we can do is determine the strength
of the association

1129
00:55:26,439 --> 00:55:30,459
between the study results of the
diagnostic test

1130
00:55:30,459 --> 00:55:34,119
of interest and the gold standard
missiles he just comparing the two how

1131
00:55:34,119 --> 00:55:36,289
well do they compare against each other

1132
00:55:36,289 --> 00:55:39,679
the strength of all of that statistical
significance is the degree of

1133
00:55:39,679 --> 00:55:44,659
correlation begin the accuracy or not
yet received the test results all the

1134
00:55:44,659 --> 00:55:49,329
two different tests that are on in this
particular set

1135
00:55:49,329 --> 00:55:52,829
clinical significance is another factor
we're not going to talk about that

1136
00:55:52,829 --> 00:55:54,209
right now

1137
00:55:54,209 --> 00:55:58,719
well what we need to do is focus on
statistical significance

1138
00:55:58,719 --> 00:56:01,639
so before we break i'm just going to

1139
00:56:01,639 --> 00:56:04,689
present to you with the way that i'm
gonna ask you

1140
00:56:04,689 --> 00:56:05,799
to think about

1141
00:56:05,799 --> 00:56:07,091
and represent that data

1142
00:56:07,091 --> 00:56:11,049
from a diagnostic study that does
exactly what

1143
00:56:11,049 --> 00:56:13,979
what i'd just out

1144
00:56:13,979 --> 00:56:17,079
a diagnostic study you are looking at

1145
00:56:17,079 --> 00:56:18,349
the

1146
00:56:18,349 --> 00:56:21,579
performance of the test of interest

1147
00:56:21,579 --> 00:56:23,076
and the gold standard he's y

1148
00:56:23,076 --> 00:56:26,019
t

1149
00:56:26,019 --> 00:56:28,259
better out there to buy two table

1150
00:56:28,259 --> 00:56:30,119
to be able to represent

1151
00:56:30,119 --> 00:56:34,469
how those the study participants a sort
themselves based on how the test of

1152
00:56:34,469 --> 00:56:35,339
interested

1153
00:56:35,339 --> 00:56:37,909
and how the gold standard label

1154
00:56:37,909 --> 00:56:40,869
across the top you always

1155
00:56:40,869 --> 00:56:44,129
you always uh... the columns are
represented by those that tested

1156
00:56:44,129 --> 00:56:45,006
positive

1157
00:56:45,006 --> 00:56:48,024
for the disease based on the gold
standard medical center

1158
00:56:48,024 --> 00:56:50,023
work theoretically calling a
hundred-percent

1159
00:56:50,023 --> 00:56:54,679
therefore each identified those in the
population who have the disease

1160
00:56:54,679 --> 00:56:57,019
and those that test negative by the gold
standard

1161
00:56:57,019 --> 00:57:00,409
will be in the second call

1162
00:57:00,409 --> 00:57:02,419
but all of these populations

1163
00:57:02,419 --> 00:57:03,077
in the study

1164
00:57:03,077 --> 00:57:07,046
there will be some of those that also
tested positive based on the

1165
00:57:07,046 --> 00:57:11,739
experimental test you're interested

1166
00:57:11,739 --> 00:57:14,619
and some that test lead

1167
00:57:14,619 --> 00:57:16,092
and sometimes they're going to agree

1168
00:57:16,092 --> 00:57:18,699
with what the gold standard says

1169
00:57:18,699 --> 00:57:22,269
such as inbox a and boxy

1170
00:57:22,269 --> 00:57:24,019
sometimes they're going to disagree

1171
00:57:24,019 --> 00:57:25,999
with what the gold standard set

1172
00:57:25,999 --> 00:57:29,239
based on box b and boxy

1173
00:57:29,239 --> 00:57:32,024
for simplicity safe keep in mind that we
arent we are

1174
00:57:32,024 --> 00:57:36,459
assuming that the gold standard is a
hundred percent

1175
00:57:36,459 --> 00:57:39,044
so we're just gonna assume that whatever
the gold standard said is true

1176
00:57:39,044 --> 00:57:42,899
and we're comparing it against test of
interest

1177
00:57:42,899 --> 00:57:46,069
each of these boxes have different names
that are going to come get introduced to

1178
00:57:46,069 --> 00:57:47,079
you

1179
00:57:47,079 --> 00:57:48,589
does that work

1180
00:57:48,589 --> 00:57:53,729
disease are are labeled correctly by
experimental tasks

1181
00:57:53,729 --> 00:58:00,199
as having the disease based on the gold
standard are called true positives

1182
00:58:00,199 --> 00:58:01,859
their inbox it

1183
00:58:01,859 --> 00:58:05,339
those that are correctly labelled as not
having the disease by the experimental

1184
00:58:05,339 --> 00:58:12,699
test relative to the gold standard are
considered true naked

1185
00:58:12,699 --> 00:58:13,089
those that are

1186
00:58:13,089 --> 00:58:17,069
falsely labeled as having the ditsy

1187
00:58:17,069 --> 00:58:18,299
based on the tax

1188
00:58:18,299 --> 00:58:21,719
but they actually build because the gold
standard sent me one

1189
00:58:21,719 --> 00:58:26,559
are called false positives

1190
00:58:26,559 --> 00:58:30,689
and those that are falsely labeled at
not having the disease

1191
00:58:30,689 --> 00:58:32,349
when they actually do

1192
00:58:32,349 --> 00:58:34,679
are called false names

1193
00:58:34,679 --> 00:58:36,769
the standard nomenclature

1194
00:58:36,769 --> 00:58:38,009
gotta remember it

1195
00:58:38,009 --> 00:58:40,061
fairly straightforward false positives
false names

1196
00:58:40,061 --> 00:58:44,199
these areas of agreement these are the
areas of disagreement

1197
00:58:44,199 --> 00:58:46,049
what we're going to do no

1198
00:58:46,049 --> 00:58:47,009
is picked up

1199
00:58:47,009 --> 00:58:49,009
with our

1200
00:58:49,009 --> 00:58:52,069
figuring out how we use this to define
test characteristics

1201
00:58:52,069 --> 00:58:55,229
so let's take a five minute break

1202
00:58:55,229 --> 00:58:57,359
and then we will come back and talk
about

1203
00:58:57,359 --> 99:59:59,999
the test characteristics better rise
from this to my teeth