Per-patient-per-month drug costs in Medicare Part D protected classes

The objective of this study was to estimate the per-patient-per-month (PPPM) costs of medications in the six Medicare Part D protected classes based on findings among Medicare and dual eligible beneficiaries with drug coverage before the enactment of the benefit.

Data were from the Thomson Medstat MarketScan Medicare and Medicaid claims databases. The study sample was constructed by identifying patients who were enrolled either in Medicare or dually in Medicare and Medicaid. PPPM costs were calculated for each protected class. Drugs covered under Part B were excluded.

PPPM aggregated costs within each class.

The classes in which generic formulations are available (antidepressants and anticonvulsants) show low PPPM costs ($ US 45.31 and $ US 50.97, respectively). The most expensive class is the antiretrovirals ($ US 829.73). This class is the costliest for all dual eligible patients including those aged 64 years and under. Among the dual eligible aged 65 years and older, the immunosuppressants are the most expensive class. The same result is seen qualitatively in the Medicare group.

PPPM costs are not uniformly high among the protected classes. The claims data in this study allowed a 'real world' check of how much the protected classes may impact the finances of Part D. There are differences within the classes between the dual eligible and Medicare patients, and also within the dual eligible by age. This is an important message to policy makers that a change to the structure of the protected classes in Part D may have differential effects across classes and also within classes.