Comparison of the psychometric characteristics of three quality of life measures in intractable epilepsy.

Understanding how epilepsy affects an individual's quality of life (QOL) requires reliable and valid QOL measures. Analyses of reliability and validity rarely examine measures obtained in the same sample, making comparisons among measures difficult. We report analyses of internal consistency reliability, face, content, construct and criterion validity for the Epilepsy Surgery Inventory-55 (ESI-55, a measure based on the SF-36 Health Survey), the Sickness Impact Profile (SIP) and the Washington Psychosocial Seizure Inventory (WPSI) administered concurrently in the same sample of intractable epilepsy patients. Results generally support the validity of all three measures in assessing the aspects of QOL they were designed to address. The ESI-55 and SIP assess a broad, multi-dimensional construct of QOL in epilepsy, compared with the more specific focus of the WPSI on psychological and social adjustment. Judged by objective psychometric criteria, the ESI-55 and SIP are preferred over the WPSI in studies of the broad impact of epilepsy on quality of life.