PND43 - adherence and persistence to anti-epileptic drugs among us veterans diagnosed with epilepsy

Abstract

OBJECTIVES: To evaluate patient adherence and persistence to anti-epileptic drug(AED) monotherapy. METHODS: Adult patients (age>18 years) with ?2 epilepsydiagnosis claims (ICD-9-CM:345) or one epilepsy diagnosis claim and one claim forother convulsion (ICD-9-CM: 780.39) were selected from the U.S. Veterans HealthAdministration database (01OCT2008-30SEPT2013). Patients were required tohave ?1 AED prescription post-epilepsy diagnosis, and the first AED prescription claim date was designated as the index date. Continuous health plan enrollment12 months pre- and post-index date was required. Patients were assigned to fourmonotherapy AED cohorts based on drug class: sodium channel blockers (SCs),gamma-aminobutyric acid analogs (GABAs), synaptic vesicle protein 2A binding(SV2) and multiple mechanisms (MMs). Adherence was assessed using the proportion of days covered (PDC) and persistence was defined as days to discontinuation with an allowable treatment gap of 45 days without the index AED. Logisticand Cox proportional hazards models were used to compare the results amongthe cohorts. RESULTS: Patients in the SC cohort had significantly lower baselineCharlson Comorbidity Index scores (1.82), indicating that they were healthier thanthose in the GAMA (2.08, p<0.001) and SV2 (2.46, p<0.001) cohorts. Patients in the SCcohort were significantly less likely to have a baseline psychiatric disorder (37.6%)than those in the GABA (63.8%, p<0.001) and MM (52.1%, p<0.001) cohorts. Patientstreated with GABAs (OR=0.44, p<0.001) and MMs (OR=0.63, p<0.001) were significantly less likely to adhere to their medications (PDC <80%) than those treatedwith SC. Furthermore, patients treated with GABAs (hazard ratio [HR]=1.74; 95%confidence interval [CI]=1.59-1.90) and MMs (HR=1.18; 95% CI=1.07-1.29) were morelikely to discontinue treatment during the follow-up period compared to those in theSC cohort. CONCLUSIONS: Patients treated with Sodium channel blockers are morelikely adhere to treatment and have lower discontinuation of AED monotherapythan those treated with GABAs and MMs.