Relationship Between the Wisconsin Stone Quality of Life (WISQOL) and Preference-Based/Health Utility Measures of Health-Related Quality of Life (HRQoL) in Kidney Stone Patients

Abstract

ObjectiveTo determine preference-based (utility) assessments of health-related quality of life (HRQoL) in kidney stone patients, and evaluate the association between these and disease specific, psychometric health status-based HRQoL scores (obtained via the Wisconsin Stone Quality of Life [WISQOL]). MethodsOne hundred four adults with urolithiasis, as well as 78 young healthy adults without history of urolithiasis (controls) were consecutively enrolled, meeting the predetermined recruitment goal. Each participant completed the SF-36 v2 (from which SF-6D utility is calculated) and EQ-5D questionnaires, while urolithiasis patients additionally completed the WISQOL. Relationship between health utility and WISQOL scores was evaluated using Pearson's test and multivariable linear regression analysis (MVA). Construct validity of the utilities for urolithiasis was assessed by comparing utilities for patients vs controls, and for symptomatic vs asymptomatic patients. ResultsMean (SD) WISQOL standard score, SF-6D, and EQ-5D utilities in stone patients respectively were 63 (29.1), 0.68 (0.16), and 0.83 (0.17). SF-6D and EQ-5D utilities significantly correlated with WISQOL standard score (Pearson's r = 0.87 and 0.58, respectively; each P <.0001). On MVA, WISQOL standard score was a significant predictor of SF-6D and EQ-5D utilities, explaining 72.1% and 33.9% of the respective variances in the utilities. Median SF-6D and EQ-5D utility were significantly lower in patients vs controls (each P ≤.0009), and in symptomatic vs asymptomatic patients (each P ≤ .0002). ConclusionSF-6D, more so than EQ-5D utilities in urolithiasis patients are strongly associated with disease-specific WISQOL scores, suggesting they are optimal for preference-based HRQoL assessment in this population. Construct validity of the utilities in stone disease was demonstrated.