An epidemiological study is conducted to learn about the relationship between celiac disease and colon cancer. Suppose there are 77 cases of colon cancer in 68,000 person-years in persons with celiac disease and 54 cases of colon cancer in 215,000 person-years in those without celiac disease. (The overall rate in both groups combined = 131 cases in 283,000 person-years overall.) Use this information to answer questions 1–3.
1. Calculate the rate of colon cancer in the celiac group (R1), in the no celiac group (R0), and overall (R). Express all rates in “per 100,000 person-years.”
2. Calculate and interpret the relative risk of colon cancer associated with celiac disease.
3. Calculate and interpret the attributable risk of colon cancer associated with celiac disease.