Question
Read the paper by Chang et al. entitled “Occupational Exposures and Risks of Liver Cancer Among Shanghai Female Textile Workers - A Case-Cohort Study” and answer the following questions.
Draw a plausible DAG for cotton-fiber/endotoxin exposure and liver cancer. Include the following covariates in your DAG: viral hepatitis B (HBV), viral hepatitis C (HCV), alcohol consumption, oral contraceptives, and aflatoxin. You also believe that there is an unmeasured common cause of HBV and HCV.
Was the study conducted in a primary or secondary study base? Was case ascertainment reasonablye complete?
What measure of effect did the authors try to estimate in this study?
How did the investigators deal with the eight women from the sub-cohort of controls who developed liver disease? Is this the appropriate method for including controls who become cases in a case-cohort study?
Source: 250B problem set
