Which data source is commonly used to capture long-term health outcomes in cohort studies?

• A. Medical records
• B. Registries
• C. Environmental measurements
• D. Questionnaires

Answer: (B)

When tracking health outcomes over many years, you need a source that can follow a defined population consistently and verify events as they occur. Registries are built for this purpose: they systematically collect data on outcomes in a defined group over extended periods and often link to death records, hospitalizations, and other health data to confirm what happened. This makes them especially reliable for observing long-term endpoints like incidence, recurrence, survival, and progression across a cohort.

Medical records can be helpful but are usually scattered across different providers and settings, making it harder to maintain complete long-term follow-up. Environmental measurements describe exposures rather than outcomes. Questionnaires can capture patient-reported outcomes but may be affected by recall bias and lack the rigorous, verifiable data needed for long-term endpoints.