Abstracts

Rationale: Multiple studies have documented an inverse relationship between healthcare utilization (eg, ER visits, hospital admissions) and AED adherence in patients with epilepsy. Extended-release (XR) formulations are designed to produce more favorable plasma concentration-time profiles, reduce dose frequency, and improve tolerability in order to increase adherence vs. their immediate-release (IR) counterparts. Using pooled data from national pharmacy claims databases, we assessed adherence, measured as Medication Possession Ratio (MPR), in patients treated with immediate-release oxcarbazepine (OXC-IR) who were switched to Oxtellar XR® (oxcarbazepine extended-release tablets, Supernus Pharmaceuticals, Inc.). Methods: Design: Retrospective observational study analyzing pooled pharmacy claims data from commercial databases (Truven MarketScan®, IMS LifeLink PharMetrics Plus™ Database, OptumInsight Clinformatics™ Data Mart Research Database, Optum Impact National Benchmark™ Dataset). Key inclusion criteria: ≥1 Oxtellar XR pharmacy claim (first claim=index date); age ≥6 yrs at index date; continuous plan enrollment 6 months pre- and 12 months post-index (study period); epilepsy diagnosis during study period. A proprietary algorithm censored duplicated patients across datasets. Analysis cohort: Subjects with OXC-IR pharmacy claim in 6-month pre-index period. Analysis: Comparison of Medication Possession Ratio (MPR) during sequential 6-month periods of OXC-IR and Oxtellar XR treatment. MPR=total days of drug supply divided by days between first and last dispensing of drug plus days of last dispensed supply. MPR categories:  ≥80%; 50% to Results: 700 patients met inclusion criteria and had been switched from OXC-IR to Oxtellar XR. Demographics: Mean age, 28 yrs; 6-17 yrs, 39%; 18-25 yrs, 21%; ≥26 yrs, 41%. 54% of patients were male. With the switch to Oxtellar XR, mean MPR increased from 66% to 72% (p < 0.001). The proportion of patients with MPR≥80% increased from 40.1% to 59.1% (p < 0.001). The proportion of patients in the MPR 50% to < 80% category decreased from 37.7% to 16.7% (p < 0.001); proportions of patients in MPR < 50% category were similar (22.1% and 24.1%). When switched to Oxtellar XR, adherence improved in 63% of patients who were nonadherent with OXC-IR (i.e., MPR < 80%). Increases in MPR were consistent across age subsets. Conclusions: The switch from OXC-IR to Oxtellar XR was associated with a significant increase across all ages in medication adherence, as measured by MPR. This study adds further support to the use of extended-release AEDs as a strategy to improve adherence and medication management. Funding: Study sponsored by Supernus Pharmaceuticals, Inc.