Abstract
ObjectivesSeveral preference-based health-related quality of life (HRQoL) instruments have been published and widely used in different populations. However no consensus has emerged regarding the most appropriate instrument in therapeutic area of stable angina. This study compared and validated the psychometric properties of two generic preference-based instruments, the EQ-5D and SF-6D, among Chinese stable angina patients.MethodsConvergent validity of the EQ-5D and SF-6D was examined with eight a priori hypotheses from stable angina patients in conjunction with Seattle Angina Questionnaire (SAQ). Responsiveness was compared using the effect size (ES), relative efficiency (RE) and receiver operating characteristic (ROC) curves. Agreement between the EQ-5D and SF-6D was tested using intra-class correlation coefficient (ICC) and Bland-Altman plot. Factors affecting utility difference were explored with multiple linear regression analysis.ResultsIn 411 patients (mean age 68.08 ± 11.35), mean utility scores (SD) were 0.78 (0.15) for the EQ-5D and 0.68 (0.12) for the SF-6D. Validity was demonstrated by the moderate to strong correlation coefficients (Range: 0.368-0.594, P< 0.001) for five of the eight hypotheses in both the EQ-5D and SF-6D. There were no serious floor effects for the EQ-5D and SF-6D, but ceiling effects for the EQ-5D were large. The areas under ROC of them all exceeded 0.5 (0.660-0.814, P< 0.001). The SF-6D showed a better discriminative capacity (ES: 0.573 to 1.179) between groups with different stable-angina-specific health status than the EQ-5D (ES: 0.426 to 1.126). RE suggested that the SF-6D (RE: 44.8 to 177.8%) was more efficient than the EQ-5D except for physical function. Poor agreement between them was observed with ICC (0.448, P< 0.001) and Bland-Altman plot analysis. Multiple liner regression showed that clinical variables significantly (P< 0.05) influenced differences in utility scores between the EQ-5D and SF-6D.ConclusionsBoth EQ-5D and SF-6D are valid and sensitive preference-based HRQoL instruments in Chinese stable angina patients. The SF-6D may be a more effective tool with lower ceiling effect and greater sensitivity. Further study is needed to compare other properties, such as reliability and longitudinal response.
Highlights
There is an increasing demand for cost-utility analysis (CUA), which allows decision-makers to compare the value of interventions for different health problems and has been adopted by many countries such as the UK and US [1,2]
Patients were included in the study if they were 18 years or above and had been clinically diagnosed with stable angina by their attending physicians based on clinical symptoms, examinations of coronary angiography, dual source Computer Tomography (CT), and history of coronary artery disease (CAD)
The analysis indicated that the 95% limits of agreement between the EQ-5D and SF-6D ranged from −0.123 to 0.335 and over 95% points lay within those limits
Summary
There is an increasing demand for cost-utility analysis (CUA), which allows decision-makers to compare the value of interventions for different health problems and has been adopted by many countries such as the UK and US [1,2]. Several preference-based instruments including the Quality of Well Being (QWB) [6], Health Utilities Index (HUI) [7], EQ-5D [8], Assessment of Quality of Life (AQoL) [9] and the SF-6D [10] have been published and widely used in different populations. Several studies have compared EQ-5D with SF-6D in different patient groups, including chronic prostatitis [13], chronic heart failure [14], coronary heart disease [15], chronic pain [16], type 2 diabetes [17], inflammatory arthritis [18] and mental health [19]. The evidence requires cumulative results from different settings and types of study [20]
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