The association of mood with quality of life ratings in epilepsy.

OBJECTIVE: To determine the relative contributions of psychological (mood and anxiety), social, and seizure-related variables to quality of life (QOL) scores in epilepsy.

METHODS: Outpatients (n = 435) with epilepsy completed the Quality of Life in Epilepsy 31 Inventory (QOLIE-31), Beck Depression Inventory II (BDI-II), Beck Anxiety Inventory, and a social survey. Stepwise linear regression and general linear model analyses determined the set of best predictors and the most unique predictors of composite QOLIE-31 score and subscale scores.

RESULTS: A three-variable model accounted for 56% of the variance for the composite QOLIE-31 score. The BDI-II was the strongest (often by several multiples in terms of variance explained) and most consistent predictor of the composite and QOLIE subscales in both types of analytic approaches. In no case did BDI-II significantly interact with the other variables, suggesting that its effect on QOL was direct and not mediated by other factors. Throughout the results, depression had an inverse relation to scores, i.e., lower levels of depression correlated with high QOL scores. Separate correlational analyses showed that poor seizure control was associated with increased numbers of depressive symptoms.

DISCUSSION: Quality of Life in Epilepsy (QOLIE) scores, reflecting both general and specific aspects of quality of life, are strongly influenced by mood state, such as depression. Factors such as seizure control exert a more limited effect on the QOLIE. Health-related quality of life measures are needed in which mood does not play such a dominant role.