Self-report of diabetes and claims-based identification of diabetes among Medicare beneficiaries.

Objective: This report compares self-reported diabetes in the National Health Interview Survey (NHIS) with diabetes identified using the Medicare Chronic Condition (CC) Summary file.

Background: NHIS records have been linked with Medicare data from the Centers for Medicare & Medicaid Services. The CC Summary file, one of several linked files derived from Medicare claims data, contains indicators for chronic conditions based on an established algorithm.

Methods: This analysis was limited to 2005 NHIS participants aged 65 and over whose records were linked to 2005 Medicare data. Linked NHIS participants had at least 1 month of fee-for-service Medicare coverage in 2005. Concordance between self-reported diabetes and the CC Summary indicator for diabetes is compared and described by demographics, socioeconomic status, health status indicators, and geographic characteristics.

Results: Of the Medicare beneficiaries in the 2005 NHIS, 20.0% self-reported diabetes and 27.8% had an indicator for diabetes in the CC Summary file. Of those who self-reported diabetes in NHIS, the percentage with a CC Summary indicator for diabetes was high (93.1%). Of those with a CC Summary indicator for diabetes, the percentage self-reporting diabetes was comparatively lower (67.0%). Statistically significant differences by subgroup existed in the percentage concordance between the two sources. Of those with self-reported diabetes, the percentage with a CC Summary indicator differed by sex and age. Of those with a CC Summary indicator for diabetes, the percentage with self-reported diabetes differed by age, self-rated health, number of self-reported conditions, and geographic location.

Conclusions: Among Medicare beneficiaries who self-reported diabetes in NHIS, a high concordance was observed with identification of diabetes in the CC Summary file. However, among Medicare beneficiaries with an indicator for diabetes in the CC Summary file, concordance with self-reported diabetes in NHIS is comparatively lower. Differences exist by subgroup.