The initial development of a health-related quality of life model as an outcome measure in epilepsy

Abstract

Patients with refractory epilepsy, despite no fixed physical deficit, are often socially and psychologically handicapped. Currently available outcome measures for epilepsy do not adequately address these manifestations or their influence on well-being and quality of life. A patient-based health-related quality of life (HRQL) model for epilepsy including physical, social and psychological domains was constructed. It contains previously validated measures of anxiety, depression, happiness, overall mood, self-esteem, mastery, social satisfaction and general health and a specifically designed seizure severity scale with patient- and carer-based components. The psychometric properties of this model were evaluated in the context of the trial of a potential new antiepileptic drug. All the scales, except the Social Problems Questionnaire, have acceptable internal consistency (alpha 0.69-0.85) in this patient population. Construct validity is indicated by the ability of the scales to differentiate between groups of patients predicted to have different levels of psychosocial function. Treatment effects were detected by the patient (P = 0.017) and carers (P = 0.035) subscales of the seizure severity scale, the happiness (P = 0.003) and the mastery (P = 0.003) scales. Despite obvious deficiencies preliminary analyses are encouraging. This model provides a framework for investigating the complex interaction between the physical, social and psychological manifestations of epilepsy. The model has potential as an outcome measure for use in longitudinal studies and as a measure of disability for use in cross-sectional studies designed to compare quality of life in different populations of people with epilepsy.