New-onset lesional and nonlesional epilepsy in the US population: Patient characteristics and patterns of antiepileptic drug use.

Purpose: Describe treatment patterns in patients from the United States with new-onset epilepsy, comparing those with and without lesional epilepsy.

Methods: In this observational study we used Truven Health MarketScan databases derived from commercial health insurance, Medicare and Medicaid claims covering at least 5 years, commencing in 2008. We identified incident epilepsy cases based on International Classification of Diseases, Ninth Revision, Clinical Modification codes indicating epilepsy or recurrent seizures, taking into account antiepileptic drug (AED) claims, consistent with International League Against Epilepsy Commission on Epidemiology recommendations. We identified patients with lesional epilepsy when associated diagnoses indicated central nervous system infection, neoplasm, traumatic brain injury, stroke, senile dementia and static encephalopathy. Lesional and nonlesional cohorts were matched 1:1 on baseline characteristics of age, sex and insurance type for group comparisons.

Results: In unmatched cohorts lesional epilepsy patients (N = 15,302) were more commonly older (mean age 48.7 years) compared with nonlesional epilepsy patients (N = 15,970; mean age 18.5 years). Among lesional patients <20 years of age, the leading putative etiology was static encephalopathy, while among ages ≥20 years and older, the leading putative etiology was stroke or cerebrovascular disease. In matched cohorts (7063 patients each), those with lesional epilepsy were significantly less likely to be untreated at 1 year versus those with nonlesional epilepsy (37.2% vs 56.1%). In children and adults among matched cohorts, levetiracetam was the most common AED prescribed for initial AED therapy for the lesional (39.5%) and nonlesional (32.1%) groups. Lesional epilepsy patients on monotherapy were only slightly less likely than nonlesional epilepsy patients to be on the same AED 1 year after treatment initiation (55.6% vs 59.7%).

Significance: Compared with patients with lesional epilepsy, a higher proportion of patients with nonlesional epilepsy remain untreated 1 year after diagnosis. There were differences in AED selection by epilepsy etiology; levetiracetam is the most commonly prescribed drug for both cohorts.