Psychometric properties of the Lithuanian version of the patient-weighted inventory on quality of life in epilepsy

Abstract

BackgroundWe aimed (1) to confirm that the Lithuanian version of the patient-weighted 31-item Quality of Life in Epilepsy Inventory (QOLIE-31-P) is a valid and reliable tool to be used among patients with epilepsy (PWE) in Lithuania and (2) to determine how the quality of life (QoL) is associated with demographic and clinical variables, adverse effects of antiseizure medication as well symptoms of depression and anxiety in this population. MethodsWe used a translated and adapted Lithuanian version of the patient-weighted 31-item Quality of Life in Epilepsy Inventory (QOLIE-31-P) and conducted a cross-sectional anonymous survey among 303 adult PWE at a tertiary epilepsy center at Vilnius University Hospital Santaros Klinikos. The questionnaire also included the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E), the Generalized anxiety disorder scale-7 (GAD-7), and the Liverpool Adverse Events Profile scale (LAEP). Missing values were replaced after performing multiple imputation (MI). ResultsQOLIE-31-P had high internal consistency (Cronbach’s α = 0.933 for all items and α = 0.676 to 0.906 for individual subscales). Its factor structure (71.2% of variance explained) consisted of seven factors, some of which overlapped (“Emotional Well-Being” and “Overall QoL”) or were split (“Social Function”) in comparison to the pre-defined content of the subscales. Multitrait-scaling revealed that each item is better correlated with the subscale it is included in than other subscales, suggesting good convergent and discriminant validity. On average, PWE scored 69.9 ± 16.8 (n = 164, mean = 64.9 after MI) on the QOLIE-31-P. Results were higher among male PWE, those employed or studying and having a higher level of education. In a pooled multiple regression model (adjusted R¯2 = 0.700, p < 0.001), the NDDIE (βst = −0.230, p < 0.001), the GAD-7 (βst = −0.226, p < 0.001), the LAEP (βst = −0.406, p < 0.001), and seizure frequency (βst = −0.156, p < 0.001) were statistically significantly associated with total QOLIE-31-P scores. ConclusionThe Lithuanian version of the QOLIE-31-P demonstrates optimal reliability and construct validity to be applied in this population. It is strongly associated with seizure frequency as well as short instruments used to measure anxiety, depression, and adverse medication effects.