PDP or MA-PD? Medicare part D enrollment decisions in CMS Region 25

The Medicare Prescription Drug Improvement and Modernization Act of 2003 provides outpatient prescription drug coverage for Medicare beneficiaries through private insurers. This coverage is available through 2 primary venues: stand-alone prescription drug plans (PDPs) and integrated managed care (or Medicare Advantage) plans that also provide prescription drug coverage (MA-PDs).

The first objective was to describe factors associated with Medicare beneficiaries choosing to enroll in any Medicare part D PDP. The second objective was to describe factors associated with the choice of an MA-PD, given enrollment in the part D program.

The study used a cross-sectional, survey design. Data were collected from a stratified random sample of 5000 community-dwelling adults, aged 65 years and older in the Center for Medicaid and Medicare Services Region 25. Data were collected by means of a mailed questionnaire. Data analyses included univariate and bivariate descriptive statistics and multivariate probit modeling.

The overall adjusted response rate was 50.2% (2309 of 4603). Data from 1490 respondents (32.4% of those attempted) were analyzed in this study. Nearly 75% of sample members elected to enroll in one of the Medicare part D coverage options in 2007, with more than 3 times as many choosing a PDP compared with a MA-PD option (57.2% vs 17.8%). A variety of variables including rurality, plan price, perceived future need for medications, and preferences emerged as important predictors of choosing to enroll in any Medicare part D drug plan, whereas rurality, state of residence, and number of diagnosed medical conditions were associated with the decision to enroll in a MA-PD.

Models of health insurance demand and plan choice applied in this context appear to be modestly effective. Rurality and state of residence were particularly important contributors to both of these decisions, as were a variety of individual characteristics.