Abstracts

2280 Adherence patterns in antiseizure medications (ASM) influencing the risk of sudden unexpected death in epilepsy (SUDEP): a data linkage study using dispensed prescriptions

Abstract

Objectives This study aims to estimate antiseizure medication (ASM) adherence and identify adherence patterns that influence epilepsy mortality.

Methods We retrospectively identified a cohort of 1,187 Australian tertiary epilepsy outpatients from 1/01/2012 until 31/12/2017. Privacy-preserving data-linkage with the national prescription, death, and coroner’s databases were performed. We fitted a 4-cluster longitudinal group-based trajectory model for ASM adherence from recurring 90-day windows of prescription dispensations during a 3-year ‘landmark period,’ 1/1/2012 to 31/12/2014. We estimated the risk of SUDEP and all-cause death for each adherence pattern during an ‘observation period,’ 1/1/2015 to 31/12/2017, using the Adhere-R package. The Cox-proportional hazards and logistic regression models were adjusted for age, sex, socioeconomic status, epilepsy duration, comorbidity, epilepsy severity and inadequate seizure control.

Results 1,187 participants were observed for a median of 3.2 years (IQR 2.4–4.0 years). We observed ≈10 cases of SUDEP during the observation period. We identified 4 patterns of ASM adherence: good 51%, declining 24%, poor 16%, and very poor 9%. Declining adherence was associated with an increased risk for SUDEP, hazard ratio 8.43 (95%CI 1.10, 64.45) at 1 year, and HR 9.17 (95%CI 1.16,72.21) at 3 years.

Conclusion Poor adherence is underappreciated and observed in half of the outpatients with epilepsy. A declining pattern of adherence, observed in a quarter of patients, is associated with more than eight times the increased risk of SUDEP. Any ongoing therapeutic interventions must be coupled with strategies to maintain and improve patient ASM adherence if we are to reduce the risk of SUDEP.

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