Background: Prior to implementation of the Medicare drug benefit, we estimated the prevalence of cost-related medication nonadherence (CRN) among Medicare enrollees, including elderly and nonelderly disabled beneficiaries.
Methods: In the fall of 2004, detailed measures of CRN (skipping or reducing doses or not filling prescriptions because of cost) were added to the Medicare Current Beneficiary Survey. We examined the prevalence of CRN nationally and by Medicare eligibility subgroups (elderly vs nonelderly disabled beneficiaries), drug coverage status, socioeconomic status, self-rated health, and number of chronic medical conditions.
Results: In a national sample of 13 835 noninstitutionalized Medicare enrollees, 29% of the disabled and 13% of the elderly beneficiaries reported CRN; those in fair to poor health with multiple comorbidities and without coverage were most at risk. Among the disabled enrollees with 4 or more morbidities, 52% (95% confidence interval [CI], 43.3%-60.3%) without drug coverage skipped prescriptions or doses compared with 26% (95% CI, 17.7%-34.8%) with Medicaid drug coverage. Those with partial drug coverage through Medigap policies or Medicare health maintenance organizations reported intermediate rates of CRN. The adjusted odds ratio of CRN among disabled enrollees in poor (vs good) health was 3.9 (95% CI, 1.7-9.2), whereas for those with 4 or more (vs <4) comorbidities, the odds ratio of CRN was 2.7 (95% CI, 1.7-4.1).
Conclusions: One year before Medicare Part D implementation, Medicare beneficiaries reported high rates of CRN. Rates are highest among nonelderly disabled beneficiaries, but among both elderly and disabled beneficiaries, CRN is exacerbated by poor health, multiple morbidities, and limited drug coverage. Given the high cost sharing under Part D, it is important to closely monitor CRN in high-risk subgroups.