The retention of lacosamide in patients with epilepsy and intellectual disability in three specialised institutions

Purpose: We describe the effectiveness of lacosamide as adjunctive therapy in patients with epilepsy and an intellectual disability. This information is relevant, as few data exist pertaining to this population with a high prevalence of (intractable) epilepsy.

Methods: We performed a retrospective study in three specialised institutions. Inclusion criteria were (1) focal onset or symptomatic generalized (2) therapy-resistant epilepsy, (3) intellectual disability and (4) residence in a care-facility for people with intellectual disabilities (PWID). The primary outcome variables were the retention rates of lacosamide, estimated through Kaplan-Meier survival analysis. Secondary outcomes were reported seizure control, side effects and clinical factors influencing discontinuation.

Results: One hundred and thirty-two patients were included. The median retention time of lacosamide in our cohort was four years. The estimated one-, two- and three-year retention rates of lacosamide were 64%, 57% and 56% respectively. Severity of intellectual disability and seizure type did not influence whether lacosamide was continued. In 48.5% of patients, a reduction of seizure activity was reported. Side effects were at least part of the reason for discontinuing treatment in 26.5% of all patients. Common side effects were tiredness/somnolence (in 30.3%), aggression/agitation (24.2%), and instable gait (15.2%). Five deaths during follow-up were considered unlikely to be related to the use of lacosamide. One patient died unexpectedly within two months of treatment onset, probably this was a case of SUDEP.

Conclusion: These retention rates of lacosamide in PWID are similar to rates of previously registered anti epileptic drugs in PWID. Behavioural side effects were noted in a high proportion compared to the general literature on lacosamide. Other side effects were in line with this literature. Lacosamide seems effective and safe for PWID and refractory epilepsy. (C) 2017 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.