The Association of Medicare Drug Coverage with Use of Evidence-Based Medications in the Veterans Health Administration

BACKGROUND: Veterans with Medicare managed-care plans have access to pharmacy benefits outside the Veterans Health Administration (VA), but how this coverage affects use of medications for specific disease conditions within the VA is unclear. OBJECTIVE: To examine patterns of pharmacotherapy among patients with diabetes mellitus, ischemic heart disease, and chronic heart failure enrolled in fee-for-service (FFS) or managed-care (HMO) plans and to test whether pharmacy benefit coverage within Medicare is associated with the receipt of evidence-based medications in the VA. METHODS: A retrospective analysis of veterans dually enrolled in the VA and Medicare healthcare systems was conducted. We used VA and Medicare administrative data from 2002 in multivariable logistic regression analysis to determine the unique association of enrollment in Medicare FFS or managed-care plans on the use of medications, after adjusting for sociodemographic, geographic, and patient clinical factors. RESULTS: A total of 369,697 enrollees met inclusion criteria for diabetes, ischemic heart disease, or chronic heart failure. Among patients with diabetes, adjusted odds ratios (ORs) of receiving angiotensin-converting enzyme (ACE) inhibitors and oral hypoglycemics in the FFS group were, respectively, 0.86 and 0.80 (p < 0.001). Among patients with ischemic heart disease, FFS patients were generally less likely to receive beta-blockers, antianginals, and statins. Among patients with chronic heart failure, adjusted ORs of receiving ACE inhibitors, angiotensin-receptor blockers, and statins in the FFS group were, respectively, 0.90, 0.78, and 0.79 (all p < 0.05). There were few systematic differences within HMO coverage levels. CONCLUSIONS: FFS-enrolled veterans were generally less likely to be receiving condition-related medications from the VA, compared with HMO-enrolled veterans with lower levels of prescription drug coverage. Pharmacy prescription coverage within Medicare affects the use of evidence-based medications for specific disease conditions in the VA.