From 28 to 6: Independent-Cohort Validation of Embedded WISQOL Short-Form Scoring in a Large Tertiary Stone Cohort

The Wisconsin Stone Quality of Life questionnaire (WISQOL) is the first validated stone-specific health-related quality of life (HRQOL) instrument. A six-item short form (WISQOL-SF) has been developed and internally validated, but evaluation of embedded SF scoring in an independent real-world cohort has not yet been performed. We aimed to evaluate embedded WISQOL-SF scoring against the full 28-item WISQOL (WISQOL-FF) in a large independent stone cohort.

We retrospectively identified 2199 patients who completed the WISQOL-FF at the University of Rochester Medical Center between February 2020 and November 2023. Standardized scores (0-100) were calculated for both the WISQOL-FF and WISQOL-SF. Agreement and reliability were assessed using paired comparisons, two one-sided tests for equivalence (±3 points), Cronbach's α, Pearson and Spearman correlations, and intraclass correlation coefficients (ICC). Construct validity was evaluated through subgroup comparisons by stone status, symptoms, emergency department visits, recent trauma, hospitalization, sex, and age.

Patients were 49.3% female with a mean age of 58.1 ± 14.9 years. The mean WISQOL-SF score was 78.0 compared with 76.2 for the WISQOL-FF (mean difference +1.8, 95% confidence interval 1.4-2.2, p < 0.001). Despite this statistical difference, equivalence testing confirmed that the scores were equivalent within the prespecified ±3-point margin. Internal consistency was high for both instruments (Cronbach's α: FF = 0.965, SF = 0.917). Agreement was excellent (Pearson r = 0.94, Spearman ρ = 0.90, ICC = 0.93). Both instruments demonstrated consistent discriminant validity, with lower HRQOL scores observed among patients with stones or symptoms, recent emergency visits, trauma, and hospitalization, and higher scores among men and older patients (all ps < 0.001).

Embedded WISQOL-SF scoring demonstrates psychometric performance comparable with the full instrument in a large independent cohort. By reducing completion time from approximately 5 minutes to about 1 minute, the WISQOL-SF offers a practical and efficient tool for assessing HRQOL in patients with kidney stone disease.