To examine adherence to monotherapy antiepileptic drug (AED) treatment for patients with focal seizures (FS) receiving eslicarbazepine acetate (ESL) vs. generic carbamazepine (CBZ) and oxcarbazepine (OXC)

AED therapy including generic AEDs like CBZ and OXC and third generation AEDs such as ESL is used to attain seizure control in patients with FS. Among other attributes, these drugs vary in their side-effect profile. Prior research suggests side-effect differences across AEDs may be associated with differences in treatment adherence. Non-adherence to AED therapy has been associated with adverse outcomes.

This retrospective cohort study analysed patient-level administrative claims data from the Quintiles IMS PharMetrics Database.  Adults with FS and prescription claims for ESL, CBZ or OXC monotherapy between April 2014 and March 2016 were included. Patients with <12 months of baseline enrolment or evidence of pregnancy at baseline were excluded. Baseline demographic and clinical characteristics of the 3 patient cohorts were examined. CBZ and OXC patients were matched 1:1 to ESL patients using propensity scores based on observable clinical and demographic factors. Adherence to AEDs was measured using proportion days covered (PDC). Proportion of patients experiencing high adherence (PDC >= 0.8) was compared via univariate testing across matched cohorts.

441, 171 and 676 patients received ESL, CBZ and OXC respectively.  Post-matching, 163 CBZ, 379 OXC patients matched to ESL comparators remained. There were no statistically significant differences in age, gender, and baseline comorbidities/AED use between matched cohorts. Proportion of patients with high adherence on ESL was significantly higher than the CBZ cohort (41.1% V. 30.1%; p=0.037). The difference in proportion of patients with high adherence on ESL and OXC was numerically higher  but non-significant (39.1% V. 34.8% p=0.23).

This real-world data suggests that patients on ESL monotherapy may be associated with similar to higher adherence rates versus patients on generic CBZ or OXC.