Development and Preliminary Validation of the 6-Item Short Form of the Wisconsin Stone Quality of Life Questionnaire

Abstract

To develop a short form of the Wisconsin Stone Quality of Life (WISQOL): 1) identify the smallest subset of items from WSIQOL that accurately predict patients' health-related quality of life (HRQOL), and 2) in a clinical patient population, test these items - grouped together to form the WISQOL-short form (SF) - and assess its convergent validity. The items for the WISQOL-SF were identified based on classic item analysis theory. Patients who previously completed the original 28-item WISQOL were randomly split into 2 groups of equal size. Scores for the WISQOL were calculated for one group while those for the WISQOL-SF were calculated for the other. Cronbach's alpha coefficients were calculated. Impacts of demographic and clinical factors as well as stone and symptom status at the time of WISQOL completion were examined. Patients (n=740) who completed the WISQOL between 6/2017-11/2021 were included. Patients were 48% male, 54.1±14.6 years old, and had a BMI of 31.2±8.1. After item analysis and reduction, the six items ultimately included in the WISQOL-SF represented 2 of the 4 domains (social and emotional) of the original WISQOL. The internal consistency of the WISQOL-SF was similar to the original (Cronbach's alpha 0.943 vs. 0.973). No differences for HRQOL were found between groups (p=0.567). The WISQOL-SF demonstrated the expected differences for gender and between patients with and without stone-related symptoms at the time of WISQOL completion. The WISQOL-SF showed good consistency and produced similar HRQOL scores to the full-form WISQOL.