Medicare beneficiary panel characteristics associated with high Part D biologic disease-modifying anti-rheumatic drug prescribing for older adults among rheumatologists.

The aim of this study was to investigate beneficiary panel characteristics associated with rheumatologists' prescribing of biologic DMARDs (bDMARDs) for older adults.In this retrospective observational study, we used Medicare Public Use Files (PUFs) to identify rheumatologists who met criteria for high-prescribing, defined as bDMARD prescription constituting ≥20% of their DMARD claims for beneficiaries ≥65 years of age. We first used descriptive analysis then multivariable regression model to test the association of high prescribing of bDMARDs with rheumatologists' panel size and beneficiary characteristics. In particular, we quantified the proportion of panel beneficiaries ≥75 years of age to assess how caring for an older panel correlate with prescribing of bDMARDs.We identified 3197 unique rheumatologists, of whom 405 (13%) met criteria for high prescribing of bDMARDs for Medicare beneficiaries ≥65 years of age. The high-prescribers provided care to 12% of study older adults, and yet accounted for 21% of bDMARD prescriptions for them. High prescribing of bDMARDs was associated with smaller panel size, and their beneficiaries were more likely to be non-black, ≥75 years of age, non-dual eligible, have diagnosis of CHF, however, less likely to have CKD.Rheumatologists differ in their prescribing of bDMARDs for older adults, and those caring for more beneficiaries ≥75 years of age are more likely to be high-prescribers. Older adults are more prone to the side-effects of bDMARDs and further investigation is warranted to understand drivers of differential prescribing behaviors to optimize use of these high-risk and high-cost medications.