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

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.