Abstracts

Rationale: Above 60 age group has the highest incidence of new onset seizures. This group also has different pharmacokinetics and pharmacodynamics making it difficult to extrapolate data from the adult antiepileptic drug (AED) clinical studies. Specifically, head to head efficacy and tolerability data on newer anti-epilepsy drugs in this population is needed. A 2013 ILAE evidence review gave Level A recommendation to only Gabapentin and Lamotrigine. Since then, clinical trials have shown comparable efficacy and better tolerability of Levetiracetam (LEV) and Lacosamide (LCS) versus Carbamazepine. In another study, LEV had similar efficacy and tolerability to Lamotrigine. However, a direct comparison of LCS & LEV has not been evaluated in this population. Methods: We analyzed data from a retrospective cohort of elderly individuals aged 60 and above with seizures who were started on LCS or LEV in our epilepsy clinic between 2008 and 2015. Patients on both LEV and LCS simultaneously were excluded. Primary outcome included retention rates at 3, 6, 12 months and the last follow-up visit. Secondary outcome included seizure freedom rate at the same time points. Retention rate was used as a measure of both efficacy and tolerability. Outcomes were compared between the two groups using chi-square test for categorical variables and Student's t-test for continuous variables. Relative risks (RR) with 95% confidence interval were calculated for outcomes across treatment groups. Results: Thirty-five LEV and twenty-one LCS patients were included in the study. There was no statistical difference between the two groups for variables of gender, age at initiation of AED, etiology, baseline seizure frequency, history of generalized tonic-clonic seizures, and EEG with interictal epileptiform discharges. Unknown etiology was the predominant cause in more than half of the patients in both groups. By comparison, patients in the LEV group were older at seizure onset (p = 0.034) and had a shorter duration of epilepsy (p = 0.014). This group also had a longer available follow-up duration (p = 0.041) with a mean of more than 3 years and was 2.3 times more likely to be on monotherapy at the last follow-up when compared to LCS group (p = 0.007). LCS group had a higher number of failed AEDs and patients with medically intractable epilepsy with a statistical trend but not significant (p = 0.06 and 0.08 respectively). Side effect incidence was similar between the two groups with behavioral changes being the most common side effect in the LEV group and dizziness being most common in LCS group. There was no statistical difference between retention rates and seizure freedom rates at 3, 6, 12 months and the last follow-up. Results are summarized in Table 1. Conclusions: LCS and LEV had similar efficacy and tolerability over close follow-up of 1 year in elderly patients with seizures. However, in comparison to the LEV group, the LCS group was likely a tougher group to treat due to earlier onset of seizures and a longer duration of epilepsy. This group had also failed more AEDs and had more patients with medically intractable epilepsy, however, this was not statistically significant. This might explain the need for LCS to be used more often in polytherapy regimen as compared to LEV. Interestingly, despite that, side effect incidence was similar between the two groups. Limitations of our study include small sample size and a disparate long-term follow-up duration between the two groups. More studies with newer AEDs are needed in the elderly population to guide clinical practice. However, based on our preliminary data, LEV and LCS have similar efficacy and tolerability in elderly patients. Funding: None