Validity and reliability of the Italian version of the Quality-of-Life in Epilepsy Inventory (QOLIE-31)

PURPOSE To develop an Italian adaptation of the shortened version of the Quality-of-Life in Epilepsy Inventory (QOLIE-31). METHODS The study population comprised 503 consecutive ambulatory patients with epilepsy from 44 centers. Internal validity was tested by factor analysis, to detect similarities to and differences from the original version, and by multitrait/multi-item analysis, to assess item convergent and discriminant validity. External validity testing included correlation to the SF-36 Inventory, to check the properties of the epilepsy-specific dimensions. Validity testing was completed by analysis of variance (ANOVA) of QOLIE-31 dimension scores against demographic and clinical variables, including age, sex, seizure frequency and number of drugs. RESULTS The domains showing the highest internal consistency and the best discriminant validity were Medication effect, and Seizure worry. Social functioning had the lower discriminant validity. With reference to the SF-36 scores, the study patients were slightly but constantly below the population values, mostly for General health and Role physical domains. All QOLIE-31 dimensions were sensitive to almost any demographic and clinical variable, except for Medication effects (sensitive to number of drugs) and Energy-fatigue (sensitive to age). CONCLUSIONS Except for Social functioning, the psychometric properties of the Italian adaptation of the QOLIE-31 Inventory are fairly good and similar to the American version and the Spanish translation. Social functioning scale suffers shortcomings because of life constraints caused by epilepsy (with missing values for regular job and driving license).