Performance of ICD10 Code-Based Dementia Case Definition in the Health and Retirement Study

The Dementia DataHub (DDH) reports U.S. dementia prevalence and incidence from Medicare data. Variation in sensitivity, specificity, and accuracy of diagnoses related to geography and participant characteristics complicates interpretation of these data.

We evaluated performance of DDH-defined Medicare claims diagnoses against linked HRS survey-based dementia classifications.

DDH's likely-or-higher dementia definition achieved 50% sensitivity, 97% specificity, and 91% accuracy relative to the HRS classification. Sensitivity was higher in urban settings, but patterns varied across census divisions. Respondents with dementia missed in claims were younger and healthier than those correctly identified.

Medicare claims reflecting diagnoses of dementia provide valuable information about who may be receiving dementia treatment and where; however, they often miss cases in ways that differ by geography and patient characteristics. Variation in diagnosis in Medicare claims relative to HRS survey-based dementia classification can be used to improve the value of Medicare diagnoses for surveillance purposes.