External validation of Stone Probability Score for screening Loei urolithiasis patients

Objective: Urolithiasis is prevalent in Thailand, particularly in Loei region. Early detection is vital for effective management. In 2022, Santanapipatkul et al. developed a Stone Probability Score for screening urolithiasis patients at Loei, however, external validation of this predictive model is necessary to ensure its reliability and applicability. The objective of this study is to externally validate the Stone Probability Score for Screening Urolithiasis Patients at Loei developed in 2022. Materials and Methods: The external validation was conducted using cross-sectional data from urolithiasis patients at Loei Hospital between June 1, 2022, and December 31, 2023. Logistic regression analysis was employed to evaluate the performance of the predictive model with regard to discrimination, calibration, and multicollinearity. Results: This validation study included 347 patients and an accuracy of 92.6% (95%CI 88.9-96.3) was achieved with an AUC pertinent to discrimination measurement resulting in a sensitivity of 96.9% (95%CI 94.2-98.6), a specificity of approximately 53.4 % (95%CI 39.9-66.7), positive predictive value of 91.2% (95%CI 87.5-94.1) and negative predictive value of 77.5% (95%CI 61.5-89.2). The performance of the model was found to be consistent after external validation in three models in comparison with the previous study. Conclusion: The external validation of SPS for Screening Loei Urolithiasis Patients exhibited excellent discrimination and calibration. The overall performance of the models was validated with high accuracy. This model can be used as a screening tool to identify individuals at risk of developing urolithiasis in the Loei region.