Abstracts

Rationale: Ethnic minorities and older adults are at higher risk of poor adherence to AEDs. The degree at which this occurs is currently unclear. We characterized AED adherence in older adults with epilepsy, and examined whether it varied across racial/ethnic groups of Medicare beneficiaries and whether differences were explained by AEDs prescribed, and personal, clinical, socioeconomic, and Medicare Part D benefit characteristics. Methods: We conducted a retrospective analysis of 2008-2010 administrative claims of a 5% random sample of Medicare beneficiaries 66 and older augmented by minority representation. Epilepsy cases in 2009 were defined as those having ?-1 ICD-9 345.x or ?-2 ICD-9 780.3x, and ?-1 AED. We measured adherence by the Proportion of Days Covered (PDC), i.e., ratio of days with ?-1 AED prescription over the total days of follow-up, with non-adherence defined as PDC < 0.80. Multiple logistic regression estimated associations of non-adherence with race/ethnicity adjusting for demographics, enzyme inducing AED, number of comorbid conditions, neurology care, socioeconomic factors (Part D Low Income Subsidy eligibility, ZIP code level poverty), Medicare Part D benefit, and region of residence. Results: Of 36,912 epilepsy cases 19.2% were white, 62.5% African American, 11.3% Hispanic, 5.0% Asian and 2% American Indian /Alaskan Native (AI/AN). Overall 31.8 % were non-adherent to AEDs; range was from 24.1% for whites to 34.3% for African Americans. Differences in non-adherence for racial/ethnic groups compared to whites were significant after adjusting for confounders. Adjusted odds ratios (OR) with 95% confidence intervals (CI) were: 1.56 (CI: 1.46-1.68) for African Americans, 1.4 (CI: 1.28-1.54) for Hispanics, 1.41 (CI: 1.25-1.54) for Asians, and 1.38 (CI: 1.16-1.65) for AI/AN. Factors associated with HIGHER likelihood of non-adherence were: being older than 85 vs. 66-74 (OR=1.08, CI: 1.02-1.15), having ?-1 comorbid conditions (1-3 vs. 0 OR=1.09, CI: 1.00-1.12, and 4+ vs. 0 OR=1.31, CI: 1.20-1.44), having ?-1 neurologist visit (OR=1.14 CI: 1.09-1.20), being from regions other than the northeast (OR=1.20, CI: 1.13-1.27), or from high poverty ZIP code areas (OR=1.16, CI: 1.11-1.21). Factors associated with LOWER likelihood of non-adherence were: being on enzyme-inducing AEDs (OR=0.85, CI: 0.81-0.89) and Low Income Subsidy eligible (OR=0.89, CI: 0.83-0.95). Compared to Part D deductible phase, being in cost-sharing phases was associated with a lower likelihood of non-adherence: copay-coinsurance (OR=0.84, CI: 0.79-0.89), coverage gap (donut hole) (OR=0.79, CI: 0.73-0.85), and catastrophic coverage (OR=0.72, CI: 0.65-0.81). Conclusions: In a diverse cohort of epilepsy cases among older Medicare beneficiaries, about a third have poor adherence to AEDs with minority groups being more at risk, e.g., African Americans. Further investigations are needed to explore reasons for non-adherence. Interventions to promote adherence are important with close attention to the impact of drug cost-sharing and socioeconomic status on epilepsy treatment. Funding: National Institute of Neurological Disease and Stroke (1R01NS080898-01).