The Spanish version of the quality-of-life in epilepsy inventory (QOLIE-31): Translation, validity, and reliability

Purpose: Spanish adaptation of the Quality of Life in Epilepsy Inventory (QOLIE-31). Methods: Internal consistency and construct validity of the Spanish translation of the QOLIE-31 were tested in 252 patients with epilepsy. Patients also were administered the General Health Questionnaire (GHQ-28), and the Nottingham Health Profile (NHP). Two weeks after the first test, a subgroup of randomly selected patients were readministered the QOLIE-31 along with a new five-option question about change in health status. Patients reporting no change in health status were included in the study of temporal stability. Sensitivity to clinical change was assessed in 31 additional patients who had successfully undergone epilepsy surgery. Results: The QOLIE-31 was highly correlated with the GHQ-28 (r = -0.63) and the NHP (r = -0.69), demonstrating construct validity. Cronbach's alpha coefficient was 0.92, showing the items of the QOLIE-31 to be interdependent and homogeneous. For a 2-week lest retest, both Pearson product-moment correlation and intraclass correlation coefficients were 0.90, indicating temporal stability. Sensitivity to clinical change was suggested by a significant mean difference between the global scores both before and after epilepsy surgery (-21.87, p < 0.0001; 95% CI, -28.08 to -15.66). The standardized response mean of the global score was 1.67, and the effect size was 1.35, both indicating large clinical change as a result of seizure relief. Conclusions: The similarity of psychometric properties between the English and the Spanish versions of the QOLIE-31 supports their conceptual equivalence. The questionnaire's responsiveness to clinical change suggests its utility in outcome assessment of drug trials and epilepsy surgery.