An epidemiologist wants to conduct a study on hepatitis C (HCV) transmission in a country with limited healthcare resources. She has access to a cohort of adults newly diagnosed with HCV and a cohort of age-matched HCV-negative adults. She plans to use these 2 cohorts of adults to conduct a case-control study. Which of the following would be the most appropriate measure of interest for this researcher's study?

Question

An epidemiologist wants to conduct a study on hepatitis C (HCV) transmission in a country with limited healthcare resources.  She has access to a cohort of adults newly diagnosed with HCV and a cohort of age-matched HCV-negative adults.  She plans to use these 2 cohorts of adults to conduct a case-control study.  Which of the following would be the most appropriate measure of interest for this researcher's study?

Quizplus · Accepted Answer

11ec160b_36fe_c3ec_9249_8f77cfdf0c1a_MD0001_00 A case-control study is an observational study design in which potential participants are initially identified as cases or controls according to their disease status (ie, have or do not have the disease of interest). In the study described above, a cohort of adults newly diagnosed with hepatitis C (HCV) represents the cases, and a cohort of HCV-negative adults represents the controls. Note that "cohort" in this case refers to a group of individuals with similar characteristics (eg, HCV-positivity), not to a "cohort study," in which a group of individuals are followed over time. Once cases and controls are identified, the frequency of past exposure to ≥1 risk factors of interest is compared between cases and controls to estimate the association between the risk factors and the outcomes. Therefore, an appropriate measure for the proposed study would be any event that preceded HCV infection. Among the given choices, a history of past blood transfusions precedes HCV infection. Because of the retrospective nature of a case-control study, this study design is not able to compare the frequency (ie, incidence, risk, rate) of any event that occurs after a disease has been diagnosed (ie, prospective outcomes). Prospective outcomes are reasonable in cohort studies and experimental designs (Choices A, C, D, and E). Educational objective: In a case-control study, potential participants are initially identified as cases or controls according to their disease status. The frequency of past exposure to ≥1 risk factors of interest is then compared between cases and controls to estimate the association between the risk factors and the outcomes.

An Epidemiologist Wants to Conduct a Study on Hepatitis C