Clinically unintended medication switches and inability to prescribe preferred medications under Medicare Part D.

Medicare Part D has expanded medication access; however, there is some evidence that dually eligible psychiatric patients have experienced medication access problems. The aim of this study was to characterize medication switches and access problems for dually eligible psychiatric patients and associations with adverse events, including emergency department visits, hospitalizations, homelessness, and incarceration. Reports on 986 systematically sampled, dually eligible patients were obtained from a random sample of practicing psychiatrists. A total of 27.6% of previously stable patients had to switch medications because clinically indicated and preferred refills were not covered or approved. An additional 14.0% were unable to have clinically indicated/preferred medications prescribed because of drug coverage/approval. Adjusting for case-mix, switched patients (p = 0.0009) and patients with problems obtaining clinically indicated medications (p = 0.0004) had significantly higher adverse event rates. Patients at greatest risk were prescribed a medication in a different class or could not be prescribed clinically-indicated atypical antipsychotics, other antidepressants, mood stabilizers, or stimulants. Patients with problems obtaining clinically preferred/indicated antipsychotics had a 17.6 times increased odds (p = 0.0039) of adverse events. These findings call for caution in medication switches for stable patients and support prescription drug policies promoting access to clinically indicated medications and continuity for clinically stable patients.