Reliability and validity of a Norwegian version of the Quality of Life in Epilepsy Inventory (QOLIE-89)

Purpose: To develop a Norwegian version of the Quality of Life in Epilepsy Inventory (QOLIE-89) and to confirm its psychometric properties. Methods: The QOLIE-89 was adapted to Norwegian language through a translation-backtranslation procedure. The assessment included 397 patients with epilepsy. We assessed internal consistency and test-retest reliabilities. Construct validity was assessed by correlating scales with items of the 15D health status questionnaire, and discriminant validity was assessed by comparing scores for known groups. Results: The internal consistency reliability (Cronbach's alpha, 0.76-0.92) and test-retest reliability (intraclass correlation coefficient, 0.67-0.96) for the individual domains were acceptable. Spearman's rank correlations between QOLIE-89 domain scores and corresponding 15D single-item scores were high (p, 0.47-0.76), and generally higher than the associations between noncorresponding items. Most QOLIE-89 items discriminated well between patients according to seizure status, psychiatric comorbidity, and working status; less well after antiepileptic drug use and neurologic comorbidity. Conclusions: In this cross-sectional survey, the Norwegian version of the QOLIE-89 was reliable and showed properties supporting construct validity, at a level comparable with the original U.S. version.