Question
The following data are from a hypothetical study on the risk of hepatitis C (HCV) among people who smoke crack cocaine with a pipe. The data are stratified by injection drug use, which you believe is a potential confounder. Hepatitis C is a blood-borne infection; smoking crack cocaine can lead to oral abrasions that plausibly increase infection risk.
a. Use the three-criteria approach to assess potential confounding by injection drug use in this study.
b. Proceeding as if injection drug use is a plausible confounder, you collect the following data:
Calculate and interpret the rate difference for HCV comparing crack pipe use to no crack pipe use separately for people who use injection drugs and people who do not use injection drugs.
c. Calculate and interpret the crude IDDpooled for crack pipe use using the combined data.
d. Calculate and interpret the adjusted IDDMH.
Source: 250B Problem Set
