400 women aged 20-35 coming for routine check-up are asked about their smoking status. 40% of the women are smokers. Over the next ten years, 25 smokers and 24 non-smokers developed breast cancer. Which of the following best describes the study design?

Question

400 women aged 20-35 coming for routine check-up are asked about their smoking status.  40% of the women are smokers.  Over the next ten years, 25 smokers and 24 non-smokers developed breast cancer.  Which of the following best describes the study design?

Quizplus · Accepted Answer

The scenario described above is a good example of prospective cohort study. Initially a group of subjects is selected (i.e., cohort) and their exposure status is determined (smoker/non-smoker). The cohort is then followed for a certain period of time and observed for development of the outcome (breast cancer). Sometimes, the exposure status is determined retrospectively and then patients are tracked from that point of time, typically using medical records (Choice B). (Choice C) A case-control study is designed by selecting patients with a particular disease (cases) and without that disease (controls) and then determining their previous exposure status. (Choice D) A cross-sectional study is also known as a prevalence study. It is characterized by the simultaneous measurement of exposure and outcome. It is a snapshot study design that frequently uses surveys. They are relatively inexpensive and easy to perform. (Choice E) A randomized clinical trial directly compares two or more treatments. Usually, the subjects are randomly assigned to an exposure (e.g., a medication) or placebo and then followed for the development of the outcome of interest. Educational Objective: Prospective cohort studies are organized by selecting a group of individuals (i.e., cohort), determining their exposure status, and then following them over time for development of the disease of interest.

400 Women Aged 20-35 Coming for Routine Check-Up Are Asked