Validation of aChinese version of the Quality of Well‐Being Scale–Self‐Administered (QWB‐SA) in patients with epilepsy

PURPOSE: Generic preference-based health-related quality of life (HRQoL) instruments are increasingly used to estimate the quality-adjusted life years (QALYs) in cost-effectiveness/utility studies. However, no such tool has been used and validated in epilepsy patients in China. This study was conducted to validate a generic preference-based HRQoL instrument, namely the Quality of Well-Being Scale-Self-Administered (QWB-SA) in Chinese patients with epilepsy. METHODS: Accepted translation procedures were followed to develop the Chinese QWB-SA. An epilepsy group (adults with established diagnosis of epilepsy) and a control group (adults without manifested cognitive problems) were recruited between July and October, 2012, from two tertiary hospitals in China. After giving informed consent, each subject completed both the QWB-SA and the EuroQol (EQ-5D) as well as provided sociodemographic data. Construct validity was examined by six (convergent) and two (discriminative) a priori hypotheses. Sensitivity was compared by ability to differentiate epilepsy-specific variable-based subgroups. Agreement between the QWB-SA and EQ-5D was assessed by intraclass correlation coefficient (ICC) and Bland-Altman plot. KEY FINDINGS: One hundred forty-four epilepsy patients and 323 control subjects were enrolled, respectively. The utility medians (interquartile range, IQR) for the QWB-SA and EQ-5D were 0.673 (0.172), 0.848 (0.275) for epilepsy group and 0.775 (0.258), 1.000 (0.152) for control group, respectively. The difference in utilities between the two measures were significant (p < 0.0001). Construct validity was demonstrated by six a priori hypotheses. In addition, the QWB-SA was able to discriminate across different seizure frequency and antiepileptic drug (AED) treatment subgroups. Agreement between the QWB-SA and EQ-5D was demonstrated by ICC (0.725). Finally, the multiple linear regression analysis indicated that group and the EQ-VAS had influences on the utility difference of these two measures, whereas seizure frequency and number of AEDs were predictors of HRQoL as measured by the QWB-SA. SIGNIFICANCE: The QWB-SA is a valid and sensitive HRQoL measure in Chinese patients with epilepsy. Compared to the EQ-5D, the QWB-SA showed superiority in coverage of health dimensions, sensitivity, and ceiling effects. However, future study is still needed to ascertain its responsiveness.