Patterns of Anti-Seizure Medication Non-adherence in Post-Stroke Prophylaxis Among Older Adults

Purpose: Anti-seizure medications (ASMs) are commonly prescribed for post-stroke seizures. Yet long-term use and non-adherence lack clear clinical guidance. We examined patterns of medication non-adherence among older adults who initiated Levetiracetam–the most frequently prescribed ASM–within 30 days after an acute ischemic stroke (AIS) discharge. Methods : We analyzed a national 20% random sample of U.S. Medicare beneficiaries aged 65 and over, who were hospitalized for a first AIS between 2009-2021 and initiated Levetiracetam within 30 days of discharge. We used an adjusted proportion of days covered (PDC) measure, accounting for prescription overlap, hospital readmissions, and non-persistency, to analyze medication non-adherence patterns during the first year after initiation. Latent class mixed models on PDC trajectories were applied to characterize patterns of non-adherence and factors associated with non-adherence. Results : In our sample of 1,697 Levetiracetam initiators, the mean age was 77.4 years, with 58% female. The latent class mixed model on PDC trajectories identified three distinct non-adherence pattern groups: (i) 907 patients (53%) were non-adherent after two months, (ii) 99 patients (6%) were non-adherent after ten months, and (iii) 692 patients (41%) remained adherent. Non-white patients and males were more likely to be non-adherent to the medication. Conclusions: The adjusted PDC method and latent class model incorporate hospital readmission and adjust for relevant covariates. Approximately 60% older adults were non-adherent to Levetiracetam within a year after outpatient initiation, with race and gender significantly associated with non-adherence patterns. This study offers both methodological innovation and clinical meaningful insights into ASM non-adherence following AIS.