Abstracts

Rationale: Lacosamide (LCM) is a newer anti-seizure medication (ASM) with relatively limited data in older adults with epilepsy (OAWE). This study aims to inform the treatment management of OAWE on LCM by comparing the rates of adverse event (AE)-related discontinuations of LCM in OAWE and younger adults with epilepsy (YAWE).

Methods: Patients with a diagnosis of epilepsy between age 18-35 years and ≥ 60 years of age and who were prescribed LCM between January 1, 2015, and July 31, 2020, in Fairview Health Services were identified. Patients were excluded if they died within 3 months of LCM initiation or lacked adequate follow-up data. Patients were required to have at least one follow-up outpatient encounter after initiation of LCM. Patients’ medical records were reviewed to evaluate key characteristics and AEs leading to discontinuation. AEs leading to discontinuation were placed into 6 AE categories: psychiatric/behavioral, cognitive, fatigue/somnolence, cerebellar, headache and other. The “other” category contained infrequent AEs that did not fit into the prior 5 categories. The primary outcome was to evaluate the rate of OAWE and YAWE who discontinue LCM due to AEs and associated factors. AE types and LCM dose were assessed in a secondary analysis. Statistical analysis for significance at alpha = 0.05 using R version 4.1.2 was performed with t-tests for means, chi-squared for proportions and Fisher’s exact for AE categories.

Results: A total of 348 patients were included in the analysis: 212 YAWE and 136 OAWE. Death within 3 months of LCM initiation excluded 79 OAWE and 7 YAWE. Initial daily LCM dose at the start of the study was similar between YAWE and OAWE reflecting different dosing starting points (already taking LCM at study start, titrating, and emergent escalation dosing). YAWE took significantly higher daily LCM doses than OAWE at the end of the study (329 mg versus 279 mg; p < 0.001). OAWE were more likely to be initiated on LCM emergently (p < 0.001) and taking a concomitant sodium channel blocker (SCB) while on LCM (p < 0.001), see table 1. For the AE discontinuation group, there was no difference in discontinuation rate due to AEs between YAWE and OAWE (11.3% versus 12.5%; p = 0.765). Daily LCM dose did not significantly differ in YAWE and OAWE (163 mg versus 226 mg; p = 0.085) in the discontinuation group. Fatigue/somnolence related discontinuation was more common in OAWE (p = 0.020) and although not significant, YAWE discontinued more commonly due to behavioral/psychiatric AEs (p = 0.1102) and OAWE discontinued more commonly due cognitive AEs (p = 0.105) (Figure 1).