Effect of Part D coverage restrictions for antidepressants, antipsychotics, and cholinesterase inhibitors on related nursing home resident outcomes.

OBJECTIVES: In 2006, Medicare Part D transitioned prescription drug coverage for dual-eligible nursing home residents from Medicaid to Medicare and randomly assigned them to Part D prescription drug plans (PDPs). Because PDPs may differ in coverage, plans may be more or less generous for drugs that an individual is taking. Taking advantage of the fact that randomization mitigates potential selection bias common in observational studies, this study sought to assess the effect of PDP coverage on resident outcomes for three medication classes--antidepressants, antipsychotics, and cholinesterase inhibitors.
DESIGN: Retrospective cohort study to examine the effect of coverage restrictions--including noncoverage and coverage with restrictions--on depression, hallucinations and delusions, aggressive behaviors, cognitive performance, and activities of daily living for dual-eligible nursing home residents randomized to PDPs in 2006 to 2008. The analyses further adjusted for baseline health status to address any residual imbalances in the comparison groups.
SETTING: Linked data from Medicare claims, Minimum Data Set assessments, pharmacy claims, and PDP formulary information. PARTICIPANTS: Dual-eligible nursing home residents aged 65 and older living in facilities that contracted with a single pharmacy provider.
RESULTS: PDP coverage restrictions in three medication classes of interest were not significantly associated with the resident outcomes examined. Although cholinesterase inhibitor users facing coverage restrictions had a 0.04-point lower depression rating score than residents facing no restrictions, this difference was not statistically significant after adjusting for multiple comparisons.
CONCLUSION: The findings suggest that exogenous changes in coverage for three commonly used medication classes had no detectable effect on nursing home resident outcomes in 2006 to 2008. There are several possible explanations for this lack of association, including the role of policy protections for dual-eligible nursing home residents and the possibility that suitable clinical alternatives were identified or that previously used medications offered little clinical benefit.