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To evaluate factors predicting efficacy, retention, and tolerability of add-on brivaracetam (BRV) in clinical practice.

A multicenter, retrospective cohort study recruiting all patients who started BRV between February and November 2016 with observation time between 3 and 12 months.

Of a total of 262 patients (mean age 40, range 5–81 years, 129 male) treated with BRV, 227 (87%) were diagnosed to have focal, 19 (7%) idiopathic generalized and 8 (3%) symptomatic generalized epilepsy, whereas 8 (3%) were unclassified. The length of exposure to BRV ranged from 1 day to 12 months, with a median retention time of 6.1 months, resulting in a total exposure time to BRV of 1,504 months. The retention rate was 79.4% at 3 months and 75.8% at 6 months. Efficacy at 3 months was 41.2% (50% responder rate) with 14.9% seizure-free for 3 months and, at 6 months, 40.5% with 15.3% seizure-free. Treatment-emergent adverse events were observed in 37.8% of the patients, with the most common being somnolence, dizziness, and behavioral adverse events (BAEs). BAE that presented under previous levetiracetam (LEV) treatment improved upon switch to BRV in 57.1% (20/35) and LEV-induced somnolence improved in 70.8% (17/24). Patients with BAE on LEV were more likely to develop BAE on BRV (odds ratio [OR] 3.48, 95% confidence interval [CI] 1.53–7.95).

BRV in broad clinical postmarketing use is a well-tolerated anticonvulsant drug with 50% responder rates, similar to those observed in the regulatory trials, even though 90% of the patients included had previously been exposed to LEV. An immediate switch from LEV to BRV at a ratio of 10:1 to 15:1 is feasible. The only independent significant predictor of efficacy was the start of BRV in patients not currently taking LEV. The occurrence of BAE during previous LEV exposure predicted poor psychobehavioral tolerability of BRV treatment. A switch to BRV can be considered in patients with LEV-induced BAE.