Choice of antiseizure medications and associated outcomes in Medicare beneficiaries after acute ischemic stroke.

Objective: We examined choice of outpatient epilepsy-specific antiseizure medication (ESM) after a stroke discharge and outcomes in a sample of US older adults.

Methods: In this matched cohort study, we analyzed a 20% sample of US Medicare beneficiaries aged 65 years and older hospitalized for acute ischemic stroke (AIS) between 2009 and 2021 who were discharged home. Individuals met insurance coverage criteria and were not taking ESM before hospitalization. We matched individuals on days from discharge to ESM initiation. Individuals who initiated ESMs other than levetiracetam within 30 days of discharge (n = 229) were matched to levetiracetam initiators (n = 687). We did not include antiseizure medications used for treatment of pain or psychiatric disorders such as gabapentin and benzodiazepines. We investigated the time to seizurelike events, emergency department (ED) visits, and readmissions using a semicompeting risk framework.

Results: The matched cohort of 916 ESM initiators had a median age of 73 years (interquartile range = 69-81) and was 57% female and 71% non-Hispanic White. Using the semicompeting risk framework, those who received other ESM had a 37% lower hazard of seizurelike events compared to those receiving levetiracetam, given that death had not occurred (hazard ratio = .63, 95% confidence interval [CI] = .43-.91). Among other ESM initiators, the hazard of ED visits and hospital readmissions, given that death had not occurred, did not differ significantly from initiating levetiracetam (hazard ratios = 1.00 [95% CI = .80-1.25] and .98 [95% CI = .75-1.28], respectively).

Significance: In a sample of US Medicare beneficiaries hospitalized for AIS and discharged home, initiating levetiracetam in the outpatient setting was associated with a higher risk of seizurelike events compared to other ESMs. However, there remains a possibility of residual confounding by indication, as individuals with greater risk of seizures may have been started on levetiracetam. We did not observe significant differences in the risk of ED visits or readmissions, suggesting comparable safety profiles in broader clinical outcomes.