Validation of Self-Reported Cancer Diagnoses by Respondent Cognitive Status in the U.S. Health and Retirement Study.

BACKGROUND: Cancer and dementia are becoming increasingly common co-occurring conditions among older adults. Yet, the influence of participant cognitive status on the validity of self-reported data among older adults in population-based cohorts is unknown. We thus compared self-reported cancer diagnoses in the US Health and Retirement Study (HRS) against claims from linked Medicare records to ascertain the validity of self-reported diagnoses by participant cognitive and proxy interview status.

METHODS: Using data from HRS participants aged ≥67 who had at least 90% continuous enrollment in fee-for-service Medicare, we examined the validity of self-reported first incident cancer diagnoses from biennial HRS interviews against diagnostic claim records in linked Medicare data (reference standard) for interviews from 2000-2016. Cognitive status was classified as normal, cognitive impairment no dementia (CIND), or dementia using the Langa-Weir method. We calculated the sensitivity, specificity, and κfor cancer diagnosis.

RESULTS: Of the 8,280 included participants, 23.6% had cognitive impairment without dementia (CIND) or dementia ,and 10.7% had a proxy respondent due to an impairment. Self-reports of first incident cancer diagnoses for participants with normal cognition had 70.2% sensitivity and 99.8% specificity (κ=0.79). Sensitivity declined substantially with cognitive impairment and proxy response (56.7% for CIND, 53.0% for dementia, 60.0% for proxy respondents), indicating poor validity for study participants with CIND, dementia, or a proxy respondent.

CONCLUSION: Self-reported cancer diagnoses in the US HRS have poor validity for participants with cognitive impairment, dementia, or a proxy respondent. Population-based cancer research among older adults will be strengthened with linkage to Medicare claims.