Determinants of quality of life in epilepsy

Abstract

Although depression is associated with diminished quality of life (QOL) in epilepsy patients, the relative contributions of epilepsy-specific concerns, as well as clinical and cognitive variables of QOL, have not been simultaneously investigated. A comprehensive neuropsychological test battery including the Beck Depression Inventory (BDI), Epilepsy Foundation of America’s (EFA) Concerns Index, MMPI-2, QOLIE-89, WAIS-III, and Selective Reminding was administered to 115 epilepsy surgery candidates with normal Full Scale IQs. Linear regression analyses were performed to identify significant predictor combinations of QOLIE-89 total score. Regression analysis demonstrated that depressive symptomatology, whether reflected by the BDI (R² = 0.45) or Depression scale of the MMPI-2 (R² = 0.36), was a robust individual QOL predictor. Seizure Worry from the EFA Concerns Index was nearly as effective as the BDI in predicting QOLIE-89 (R² = 0.42). When the BDI and EFA Concerns Index were combined into the same regression, both factors continued to contribute significantly to the QOLIE-89 total score, with both variables accounting for 61% of the variance. Although patients who developed their seizures at an older age had poorer QOL and patients with higher educational levels reported higher QOL, neither factor was related to QOL after accounting for the effects of psychological variables and epilepsy-related concerns. Although quality of life has multiple determinants, symptoms of depression and seizure worry are the most important factors affecting QOL in patients with intractable epilepsy.

Introduction

Over the past decade, there has been increased interest in how epilepsy and its treatment affect the quality of life (QOL) of epilepsy patients. Disease-specific QOL influences contrast with general life satisfaction factors that independently affect QOL. In epilepsy, QOL measures have been used not only to characterize disease burden, but also to reflect the effects of AED treatment [1], [2], [3], seizure severity [4], and epilepsy surgery [5], [6], [7].

A common measure of QOL scales is the Quality of Life in Epilepsy—89 (QOLIE-89) [8]. Although multiple content scores can be derived, the most common summary measure is the overall QOLIE-89 score. The usefulness of the summary score is evident in the multiple short forms of the QOLIE that contain many fewer questions, but generate an overall score with fewer content scales (i.e., QOLIE-31, QOLIE-10) [9], [10].

A parallel development to study the experience of epilepsy on everyday activities is reflected in the Epilepsy Foundation of America (EFA) Concerns Index [11]. The EFA Concerns Index is a 20-item scale on which patients rate specific epilepsy concerns (e.g., being a burden or worry to family), and was derived from epilepsy patients who listed their concerns over living with recurrent seizures in order of importance [12]. The EFA Concerns Index has been successful in demonstrating the beneficial effects of anterior temporal lobectomy [11].

Epilepsy is relatively unique among chronic neurologic diseases in its potential influence on QOL. Epilepsy often begins at a young age and may hinder social and cognitive development. In addition, epilepsy is episodic, occurs unpredictably, and typically involves loss of consciousness, leading to driving and employment restrictions. Importantly, epilepsy is associated with high rates of psychiatric comorbidity [13], [14], [15], [16], and among psychiatric inpatients, the association between disease and QOL is greatest for patients with depression [17]. The effect of depressive symptomatology on QOL in epilepsy is strong, in many reports accounting for approximately half of the variance when compared with formal QOL measures [16], [18], [19]. After accounting for the effects of depression, other potentially relevant clinical factors are either unrelated to QOLIE-89 or account for very small amounts of the QOLIE-89 total score, suggesting that dysphoria and stress-related complaints overshadow the effects of other variables. In the present study, we describe the relative contributions of specific epilepsy concerns to two commonly employed measures of depression to determine their relative contributions to QOL. In addition, we explore the role of clinical factors and cognition in QOL.