Adherence to antiepileptic drugs among diverse older Americans on Part D Medicare

- About a third of diverse older adults with epilepsy had poor adherence to antiepileptic drugs.
- Minority groups were more likely to have poor adherence.
- Poor adherence was also associated with drug cost sharing and poverty.

IntroductionOlder minority groups are more likely to have poor AED adherence. We describe adherence to antiepileptic drugs (AEDs) among older Americans with epilepsy.MethodsIn retrospective analyses of 2008-2010 Medicare claims for a 5% random sample of beneficiaries augmented by minority representation, epilepsy cases in 2009 were those with ≥ 1 claim with ICD-9345.x or ≥ 2 with 780.3x, and ≥ 1 AED. New-onset cases had no such claims or AEDs in the year before the 2009 index event. We calculated the Proportion of Days Covered (PDC) (days with ≥ 1 AED over total follow-up days) and used logistic regression to estimate associations of non-adherence (PDC < 0.8) with minority group adjusting for covariates.ResultsOf 36,912 epilepsy cases (19.2% White, 62.5% African American (AA), 11.3% Hispanic, 5.0% Asian and 2% American Indian/Alaskan Native), 31.8% were non-adherent (range: 24.1% Whites to 34.3% AAs). Of 3706 new-onset cases, 37% were non-adherent (range: 28.7% Whites to 40.5% AAs). In adjusted analyses, associations with minority group were significant among prevalent cases, and for AA and Asians vs. Whites among new cases. Among other findings, beneficiaries from high-poverty ZIP codes were more likely to be non-adherent than their counterparts, and those in cost-sharing drug benefit phases were less likely to be non-adherent than those in deductible phases.ConclusionAbout a third of older adults with epilepsy have poor AED adherence; minorities are more likely than Whites. Investigations of reasons for non-adherence, and interventions to promote adherence, are needed with particular attention to the effect of cost-sharing and poverty.