Variation in Prescription Drug Coverage Enrollment Among Vulnerable Beneficiaries With Glaucoma Before and After the Implementation of Medicare Part D.

IMPORTANCE: It is important to understand in more detail how patients with glaucoma were affected by the implementation of Medicare Part D, which was designed to provide beneficiaries with near-universal prescription drug coverage.

OBJECTIVES: To determine changes in prescription drug coverage and out-of-pocket spending after the implementation of Medicare Part D across income strata and to identify characteristics of beneficiaries associated with prescription status.

DESIGN, SETTING, AND PARTICIPANTS: Longitudinal observational study in the general community using the Medicare Current Beneficiary Survey (pooled 2004, 2005, 2007, and 2008 data). Participants were noninstitutionalized Medicare beneficiaries who filled at least 1 glaucoma prescription during the survey years. The dates of this analysis were January 2004 to December 2009.

MAIN OUTCOMES AND MEASURES: Effect of the implementation of the Medicare Part D drug benefit, including prescription drug coverage and risk-adjusted out-of-pocket spending related to glaucoma medications.

RESULTS: Respondents included 12,079 participants in the 2004 survey, 11,089 participants in the 2005 survey, 11,995 participants in the 2007 survey, and 11,723 participants in the 2008 survey. The sample included 19,045 glaucoma prescriptions, and 2519 Medicare beneficiaries filled at least 1 glaucoma prescription during the study years. Overall 574 (22.8%) beneficiaries reported living below the poverty level, and 795 (31.6%) had incomes consistent with near-poor status. The implementation of Medicare Part D resulted in increased rates of prescription drug coverage across all economic strata, with reductions in beneficiaries without coverage from 22.8% to 4.0%, 29.1% to 7.3%, and 19.9% to 3.7% among poor, near-poor, and higher-income beneficiaries, respectively. Despite these gains, near-poor status remained a risk factor for lack of prescription drug coverage after the implementation of Medicare Part D (odds ratio, 2.46; 95% CI, 1.26-4.55; P = .04). No differences were identified in adjusted out-of-pocket prescriptions drug costs between the near poor and those with higher income, although out-of-pocket costs were 37% (95% CI, 26%-49%; P < .001) lower among the poor relative to those with higher income.

CONCLUSIONS AND RELEVANCE: Medicare Part D enrolled most beneficiaries with glaucoma who previously lacked prescription drug coverage. The results of this study suggest that coverage gains lagged among the near poor. While these data evaluated changes in coverage among cohorts of beneficiaries and not from longitudinal follow-up of patients, targeted efforts to improve prescription drug coverage among vulnerable beneficiaries would likely improve access to prescribed ocular hypotensive medications.