Health and Retirement Study Sample

To compare the prevalence of medical conditions among the former ND football players with that among men in the general population, we used data from the Health and Retirement Study (HRS),⁴⁴ a longitudinal study of a representative sample of US adults older than 50 years. The HRS is sponsored by the National Institute on Aging and conducted by the University of Michigan. University of Notre Dame survey questions were harmonized with HRS 2016 survey questions (eTable 1 in the Supplement).⁴⁴ In both surveys, participants provided responses to questions about diagnoses and treatment provided by health care workers, with similar or identical wording used in the surveys. The ND survey included additional questions or more details for diagnostic categories for which there were no parallel HRS items.