Assessing Medicare Part D claim completeness using medication self-reports: the role of veteran status and Generic Drug Discount Programs.

OBJECTIVE: Medicare Part D claims are commonly used for research, but missing claims could compromise their validity. This study assessed 2 possible causes of missing claims: veteran status and Generic Drug Discount Programs (GDDP).
MATERIALS AND METHODS: We merged medication self-reports from telephone interviews in the Atherosclerosis Risk in Communities (ARIC) Study with Part D claims for 6 medications (3 were commonly in GDDP in 2009). Merged records (4468) were available for 2905 ARIC participants enrolled in Part D. Multinomial logit regression provided estimates of the association of concordance (self-report and Part D, self-report only, or Part D only) with veteran and GDDP status, controlling for participant sociodemographics.
RESULTS: Sample participants were 74±5 years of age, 68% white and 63% female; 19% were male veterans. Compared with females, male veterans were 11% [95% confidence interval (CI), 7%-16%] less likely to have matched medications in self-report and Part D and 11% (95% CI, 7%-16%) more likely to have self-report only. Records for GDDP versus non-GDDP medications were 4% (95% CI, 1%-7%) more likely to be in self-report and Part D and 3% (95% CI, 1%-5%) less likely to be in Part D only, with no difference in self-report only.
CONCLUSIONS: Part D claims were more likely to be missing for veterans, but claims for medications commonly available through GDDP were more likely to match with self-reports. Although researchers should be aware of the possibility of missing claims, GDDP status was associated with a higher rather than lower likelihood of claims being complete in 2009.