We sought to examine the impact of depression upon antiepileptic drug (AED) adherence in patients with epilepsy. We administered the Center for Epidemiologic Studies Depression Scale (CES-D), Neurological Disorders Depression Inventory for Epilepsy (NDDI-E), Seizure Severity Questionnaire (SSQ), and Quality of Life in Epilepsy-10 (QOLIE-10) and measured AED adherence by utilizing the medication possession ratio (MPR) in adult patients with epilepsy identified through a pharmacy claims database. From a sampling frame of over 10,000 patients identified in claims, 2750 were randomly selected and contacted directly by mail to participate in the cross-sectional survey. A total of 465 eligible patients completed a survey. Survey data were combined with administrative claims data for analysis. We conducted a path analysis to assess the relationships between depression, adherence, seizure severity, and quality of life (QOL). Patients with depression scored significantly worse on measures of seizure severity (p=.003), QOL (p<.001), and adherence (p=.001). On path analysis, depression and QOL and seizure severity and QOL were related, but only the NDDI-E scores had a significant relationship with medication adherence (p=.001). Depression as measured by the NDDI-E was correlated with an increased risk of AED nonadherence. Depression or seizure severity adversely impacted QOL. These results demonstrate yet another important reason to screen for depression in epilepsy.
Keywords: Adherence; Antiepileptic drug; Depression; Quality of life; Seizure severity.
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