Development and preliminary validation of a diagnostic prediction model to optimise outpatient management of patients with urolithiasis using urinary stones and intervention quality of life (USIQoL) measure.

Purpose: Patients with urinary calculi undergo resource-intensive follow-up. Application of a PROM, Urinary Stones and Intervention Quality of Life (USIQoL), can potentially optimise current practices if it matches the outcomes of traditional follow-up. Our objective was to develop, and conduct, a preliminary validation of the USIQoL based prediction model to aid triage.

Methods: We performed a two phase prospective cohort study. The 1st phase included development of the USIQoL-based decision model using multicentre data. The 2nd phase involved prospective single-blind external validation for the outpatient application. The aim was to evaluate correlations between the USIQoL scores and key predictors; clinical outcomes and global health ratings (EuroQoL EQ-5D). We used statistical analysis to validate USIQoL cut-off scores to aid triage and the decision to intervene.

Results: Of 503 patients invited, 91% (n = 455, Development [305] and Validation [150]; M = 308, F = 147) participated. The relationship between USIQoL domain scores and clinical outcomes was consistently significant (estimated odds: PPH 1.24, p < 0.001, 95% CI 1.13-1.36; PSH 1.22, p < 0.001, 95% CI 1.12-1.33). The ROC values for the model were ≥ 0.75. The optimum domain cut-off scores were derived with rising scores implying increased need to intervene. The model demonstrated satisfactory sensitivity (0.81-0.89) and specificity (0.36-0.47).

Conclusions: The study demonstrates satisfactory correlation between the USIQoL and clinical outcomes making this model a valid aid for triage and optimising outpatient management with the cut-off scores able to identify high risk patients who need active treatment.