Urinary Stones and Intervention Quality of Life (USIQoL): Development and Validation of a New Core Universal Patient-reported Outcome Measure for Urinary Calculi

Abstract

Background: Urolithiasis has a significant impact on patients' health-related quality of life (HRQoL).

Objective: To develop a core patient-reported outcome measure (PROM) using modern psychometric methods to quantify the impact of urolithiasis and different treatments.

Design, setting, and participants: Adult patients with urinary calculi, attending urology departments, covering all index categories and treatment spectrum, participated during different development phases. The pilot instrument was created from potential items (phases 1 and 2) within the conceptual framework. The instrument was pretested (phase 3) and then underwent psychometric evaluation in two parts (phases 4 and 5).

Outcome measurements and statistical analysis: The validity and reliability of the new PROM were assessed using Rasch measurement theory (RUMM 2030 statistical software) and traditional analyses.

Results and limitations: In total, 683 patients (median age 51 yr, range 18-92 yr) participated during different phases. The initial 60-item draft (five scales) was completed by 212 patients (phase 4). A revised 25-item draft was produced after removal of unstable items. In the second field test, the revised version was evaluated by 369 patients. This led to the final Urinary Stones and Intervention Quality of Life (USIQoL; 15 items) with summated logit scores. The PROM includes three scales: pain with physical health (six items), psychosocial health (seven items) and work performance (two items). Lower scores indicate better outcomes. Results demonstrate that USIQoL is reliable (r ≥ 0.8) and internally consistent (α ≥ 0.7), and has good construct validity (good hypothesised correlations, r > 0.3) and satisfactory sensitivity to change (p < 0.01). All scales demonstrated unidimensionality with good item fit and person separation indices. A limitation is that USIQoL was developed in the English language within the UK population.

Conclusions: USIQoL is a short, unidimensional, valid, and reliable PROM for assessing the HRQoL impact of urinary calculi and treatments. It is expected to serve as a core PROM across the entire spectrum of urolithiasis.

Patient summary: Kidney stones are a common condition for which various treatment options are available. The condition and treatments have a significant impact on a patient's quality of life. This can be measured objectively using a valid and reliable patient-reported outcome measure (PROM) developed using modern methods. We have developed a PROM that provides helpful and accurate measurement useful for all stakeholders.

Keywords: Outcomes; health related quality of life (HRQoL); patient reported outcome measure (PROM); stones and intervention; urinary calculi.