Medicare part D's impact on antipsychotic drug use and costs among elderly patients without prior drug insurance.

Medicare part D's implementation improved access to and affordability of prescription drugs for the elderly without prior drug insurance. Effects for specific drugs and drug classes are less well understood. We assessed part D's impact on antipsychotic medication (APM) utilization and out-of-pocket costs among elderly without prior drug insurance. Retail pharmacy claims from 3 nationwide pharmacy chains were used to analyze 2 time-series designs: (1) a policy model, to obtain a policymaker's perspective: what was the overall impact of part D on APM use and costs among elderly without drug insurance in 2005 with the opportunity to enroll? And (2) a clinical model, to obtain a clinician's perspective: what would happen to elderly without drug insurance in 2005 who did enroll in part D--would they be able to get APMs? At what cost? Subgroup analyses among part D enrollees evaluated potentially different effects for patients who received a subsidy and patients who used antidementia drugs. In the policy model, part D implementation was associated with a 5% increase in APM use and a 37% reduction in out-of-pocket costs, suggesting a modest need for APMs among all previously uninsured elderly. Patients who did enroll in part D (clinical model) had a 97% increase in APM use and a 62% decrease in out-of-pocket costs, suggesting that patients who needed APMs were able to access them at low cost through the part D program. Part D implementation was associated with increased use and affordability of APMs for the elderly without prior drug insurance.