Reliability and validity of a Norwegian version of the quality of life in epilepsy inventory (QOLIE-89).
To develop a Norwegian version of the Quality of Life in Epilepsy Inventory (QOLIE-89) and to confirm its psychometric properties. 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. 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. 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.