The Baltimore study described, in which a group was asked about alcohol consumption in 1965 and cancer occurrence was studied from 1981 to 1995, is an example of which study design?

The Baltimore study described, in which a group was asked about alcohol consumption in 1965 and cancer occurrence was studied from 1981 to 1995, is an example of which study design?

• A. Cross-sectional
• B. Concurrent cohort
• C. Retrospective cohort
• D. Case-control

Answer: (B)

In this setup, the key idea is temporality: you start with a defined group and establish who was exposed, then you follow them over time to see who develops the outcome. Here, exposure to alcohol is assessed in 1965, and cancer occurrences are tracked during 1981–1995. That sequence—exposure first, outcomes later—is the hallmark of a cohort design. The label concurrent cohort reflects that the study follows the same group over time to observe the outcome after exposure, even if some data may be gathered after the fact from records. This isn’t a cross-sectional picture, where exposure and outcome are assessed at one point, and it isn’t case-control, which starts with disease status and looks back to exposure. The defining feature here is watching a defined exposed group over time to measure the subsequent incidence of cancer.

In this setup, the key idea is temporality: you start with a defined group and establish who was exposed, then you follow them over time to see who develops the outcome. Here, exposure to alcohol is assessed in 1965, and cancer occurrences are tracked during 1981–1995. That sequence—exposure first, outcomes later—is the hallmark of a cohort design. The label concurrent cohort reflects that the study follows the same group over time to observe the outcome after exposure, even if some data may be gathered after the fact from records.

This isn’t a cross-sectional picture, where exposure and outcome are assessed at one point, and it isn’t case-control, which starts with disease status and looks back to exposure. The defining feature here is watching a defined exposed group over time to measure the subsequent incidence of cancer.