Impact of Medicare Part D for Medicare-age adults with arthritis: prescription use, prescription expenditures, and medical spending from 2005 to 2008.

OBJECTIVE: To evaluate the impact of Medicare Part D on medication utilization, drug expenditures, and medical expenditures in patients with arthritis.

METHODS: This was a retrospective study using a national sample of 2,484 Medicare-eligible beneficiaries with arthritis from the pooled Medical Expenditure Panel Survey 2005-2008 data. Quantile regression was used to estimate the following outcomes: 1) number of prescription fills, 2) total drug expenditures, 3) out-of-pocket (OOP) drug expenditures, 4) Medicare-paid drug expenditures, 5) total medical expenditures (including all payments for inpatient/outpatient care, prescription drugs, and other medical services), 6) OOP medical expenditures, and 7) Medicare-paid medical expenditures. For each outcome variable, the 50th, 75th, and 90th percentiles were estimated, adjusting for demographics and comorbidity. All expenditures were inflation adjusted to 2008 dollars.

RESULTS: From 2005 to 2008, the adjusted median annual number of prescription fills increased by 4.2 (14.6% change), from 28.4 to 32.6. The adjusted median OOP drug expenditures and OOP medical expenditures decreased by $151 (25.2% change) and $197 (17.3% change), respectively. The adjusted median Medicare-paid drug and medical expenditures increased by $366 and $896 (39.5% change), respectively. The adjusted total prescription expenditures increased by $845 (25.3% change) at the 75th percentile and by $1,194 (22.0% change) at the 90th percentile. The adjusted total medical expenditures did not change significantly.

CONCLUSION: Medicare Part D resulted in increased medication utilization and significant reductions in OOP drug and OOP medical expenditures among beneficiaries with arthritis 3 years after its implementation. Part D was not associated with significant differences in total medical spending.