lesson #11 relative risk and the odds ratio
DESCRIPTION
Lesson #11 Relative Risk and the Odds Ratio. P(D | E). The risk of disease, given exposure, is:. The risk of disease, given no exposure, is:. P(D | E’). The relative risk is. LC no LC. Smoke. 12. 88. 100. No Smoke. 150. 3. 147. P(LC | Smoke). = .12. P(LC | No Smoke). - PowerPoint PPT PresentationTRANSCRIPT
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Lesson #11
Relative Risk andthe Odds Ratio
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The risk of disease, given exposure, is:
The risk of disease, given no exposure, is:
The relative risk isP(D | E)
RR =P(D | E' )
P(D | E)
P(D | E’)
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LC no LCSmoke
No Smoke
12
3
88
147
100
150
P(LC | Smoke)12
=100 = .12
=3
150P(LC | No Smoke) = .02
RR =P(LC | Smoke)
P(LC | No Smoke).12
= .02
= 6
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D D’
E
E’
Cohort Study
En
E 'n
n
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p1- pIf p = P(event), then odds =
The odds of disease, given exposure:
P(D | E)1 - P(D | E)
P(D | E)=
P(D' | E)
The odds of disease, given no exposure:
P(D | E' )1 - P(D | E' )
P(D | E' )=
P(D' | E' )
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Disease Odds Ratio
P(D | E) P(D' | E)/OR =
P(D | E' ) P(D' | E' )/
P(D | E) P(D' | E' )=
P(D | E' ) P(D' | E)
Can calculate as shown only from a cohort study
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Case-Control Study
Dn
D 'n n
D D’
E
E’
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From a case-control study, we can calculate things like:
P(E | D) , P(E’ | D) , P(E | D’ ) , & P(E’ | D’ )
The odds of exposure, given disease:
P(E | D)1- P(E | D)
P(E | D)=
P(E' | D)
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Exposure Odds Ratio
OR
P(E | D) P(E' | D' )=
P(E | D' ) P(E' | D)
Can calculate as shown from a case-control study
P(E | D) P(E' | D)=
P(E | D' ) P(E' | D' )//
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P(E' | D' )P(E | D' P(E | D)
= P(E' )) | D
OR
D D’
E
E’
a b
c d
a+c b+d
OR =
aa + c
ca + c
db + d
bb + d
= adbc
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= adbc
The disease odds ratio is also OR
OR is used to estimate RR!
OR can be calculated in any study design!
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CHD no CHD
High Fat
not High Fat
200 300
180
120
50
150
OR =
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CHD no CHD
High Fat
not High Fat
200 300
180
120
50
150
OR = (150)
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CHD no CHD
High Fat
not High Fat
200 300
180
120
50
150
OR = (150)(180)
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CHD no CHD
High Fat
not High Fat
200 300
180
120
50
150
OR = (150)(180)
(120)
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CHD no CHD
High Fat
not High Fat
200 300
180
120
50
150
OR = (150)
(50)
(180)
(120)
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CHD no CHD
High Fat
not High Fat
200 300
180
120
50
150
OR = (150)
(50)
(180)
(120)= 4.5
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CHD no CHD
HF
not HF
200 300
180
120
50
150
CHD no CHD
HF
not HF
200 600
360
240
50
150
OR = (150)
(50)(180)
(120)= 4.5
OR = (150)
(50)(360)
(240)= 4.5
“RR” = = 2.56150/270
50/230
“RR” = = 3.15150/39050/410
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Yes No
Heavy
Light
None
46
33
10
89
39
82
32
153
Liver Cancer
Alc
ohol
Con
sum
ptio
n
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Yes No
Heavy
Light
None
46
33
10
89
39
82
32
153
HN
(46)(32)OR = = 3.77
(39)(10)
Liver Cancer
Alc
ohol
Con
sum
ptio
n
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Yes No
Heavy
Light
None
46
33
10
89
39
82
32
153
HN
(46)(32)OR = = 3.77
(39)(10)
LN
(33)(32)OR = = 1.29
(82)(10)
Liver Cancer
Alc
ohol
Con
sum
ptio
n