Lesson #11 Relative Risk and the Odds Ratio

The risk of disease, given exposure, is: The risk of disease, given no exposure, is: The relative risk is P(D | E) P(D | E’)

LC no LC Smoke No Smoke P(LC | Smoke) =.12 P(LC | No Smoke) =.02 RR = = 6

D D’ E E’ Cohort Study n

If p = P(event), then odds = The odds of disease, given exposure: The odds of disease, given no exposure:

Disease Odds Ratio OR = Can calculate as shown only from a cohort study

Case-Control Study n D D’ E E’

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:

Exposure Odds Ratio OR Can calculate as shown from a case-control study

OR D D’ E E’ ab cd a+cb+d OR =

The disease odds ratio is also OR OR is used to estimate RR! OR can be calculated in any study design!

CHD no CHD High Fat not High Fat OR =

CHD no CHD High Fat not High Fat OR = (150)

CHD no CHD High Fat not High Fat OR = (150)(180)

CHD no CHD High Fat not High Fat OR = (150)(180) (120)

CHD no CHD High Fat not High Fat OR = (150) (50) (180) (120)

CHD no CHD High Fat not High Fat OR = (150) (50) (180) (120) = 4.5

CHD no CHD HF not HF CHD no CHD HF not HF OR = (150) (50) (180) (120) = 4.5OR = (150) (50) (360) (240) = 4.5 “RR” == /270 50/230 “RR” == /390 50/410

Yes No Heavy Light None Liver Cancer Alcohol Consumption

Yes No Heavy Light None Liver Cancer Alcohol Consumption

Yes No Heavy Light None Liver Cancer Alcohol Consumption