Criteria for the evaluation of large cohort studies: an application to the nurses' health study.

Evaluating the success of major funding programs from the National Institutes of Health (NIH) remains a vexing challenge. We propose a set of criteria to evaluate epidemiological studies that fit within the discovery, development, and delivery paradigm introduced by the NIH. We apply these criteria to the Nurses' Health Study (NHS), a large epidemiological cohort study initiated in the 1970s to evaluate the associations between oral contraceptives and risk of breast cancer and between diet and other lifestyle factors and risk of cancer overall. Our evaluation suggests that the NHS has led to important changes in health practice, and it underscores the need to develop metrics that are suitable to the evaluation of large epidemiological cohort studies.