Psychometric properties and comparison of four health utility approaches among myopia patients in China

Abstract

Background The increased prevalence of myopia creates and earlier age of onset has created public health concerns for the long-term eye health, vision impairment and carries with it a significant economic burden. The quality of the economic evaluation is dependent on the sensitivity and validity of the approaches. Nowadays, there are many approaches to measure patients’ health state utility (HSU). However, little is known regarding the performance of direct approach and indirect approach in people with myopia. This study is aimed to compare the psychometric properties of four HSU approaches among patients with myopia in mainland China, including two direct approaches (TTO and SG), the generic preference-based measures (PBM) (AQoL-7D) and the disease-specific PBM (VFQ-UI). Methods A convenience sampling framework was used to recruit patients with myopia who attended a large ophthalmic hospital in Jinan, China. Spearman’s rank correlations coefficient was used to assess concurrent validity. Known-group validity was analyzed by: (1) whether the patients wear corrective devices; (2) severity of myopia as low or moderate to high of the better eye; (3) duration of myopia as ≤ 10 years or > 10 years. Effect size (ES), relative efficiency (RE) statistic and the largest area under the receiver operating characteristic curve (AUC) were used to assess sensitivity. The intra-class correlation coefficient (ICC) and Bland–Altman plots were used to assess agreement. Results A valid sample size of 477 myopia patients was analyzed (median duration: 10 years). The mean HSU scores between TTO and SG were similar (0.95) and higher than AQoL-7D (0.89) and VFQ-UI (0.83). Overall, the VFQ-UI had the best performance based on the psychometric analysis. The agreement indicated that there was no pair of approaches that could be used interchangeably. Conclusions The VFQ-UI showed better psychometric properties than other three approaches for providing health state utility in Chinese myopia patients. Given the widespread use and its generic nature of the AQoL-7D, it could be used alongside with VFQ-UI to provide complementary health state utility from a generic and disease-specific perspective for economic evaluation. More evidence on the responsiveness of four health utility approaches in myopia patients is required.