S.T.O.N.E. Score Effective in Predicting Stone-Free Outcomes After Ureteral Lithotripsy: Study Shows

"The S.T.O.N.E. score proves to be a valuable predictor of stone-free rates following ureteral lithotripsy, facilitating better preoperative planning and aiding in identifying patients at higher risk of treatment failure," the researchers wrote.

Ureteral lithotripsy is a widely used treatment for ureteral stones, yet predicting its success remains a clinical challenge. In response, Faisal Ahmed, Department of Urology, School of Medicine, Ibb University, Ibb, Yemen, and colleagues evaluated the S.T.O.N.E. score—a composite measure that incorporates five key factors: stone Size, Topography (location), degree of Obstruction, Number of stones, and Hounsfield units (HU) from CT imaging—to assess its ability to forecast treatment outcomes.

The study retrospectively analyzed data from 266 patients who underwent ULT at IBB University Hospitals between April 2021 and September 2023. The patient population had a mean age of 47.7 years, and the majority (72.2%) were male. Preoperative CT scans were used to calculate the S.T.O.N.E. score for each participant, and a predictive model was developed to assess the likelihood of residual stones post-procedure.

The study revealed the following findings:

• The average S.T.O.N.E. score among the patients was 7.8.
• A total of 85.3% of patients achieved stone-free status following ureteral lithotripsy (ULT), while 14.7% had residual stone fragments.
• Key predictors of treatment failure included higher Hounsfield units, larger stone size, proximal stone location, and moderate to severe hydronephrosis.
• Patients with a S.T.O.N.E. score greater than eight were found to have a higher likelihood of treatment failure.
• The predictive model demonstrated an overall accuracy of 85.0%, with a sensitivity of 72.0% and specificity of 81.0%.
• The area under the ROC curve confirmed the strong ability of the model to distinguish between outcomes.
• Calibration analysis showed a close match between predicted and actual results.
• Decision curve analysis indicated the model's clinical utility by effectively stratifying patients into high- and low-risk categories.

“The S.T.O.N.E. score offers a practical and efficient method for preoperatively estimating the likelihood of residual stones,” the authors noted. “It allows clinicians to tailor surgical plans and counsel patients more effectively based on individualized risk.”

The study concludes that integrating the S.T.O.N.E. score into routine urological assessment may optimize surgical planning and resource utilization. However, the authors emphasize the importance of further validation across broader and more diverse populations before universal adoption. Future multicenter trials are encouraged to assess its applicability in varied clinical environments and to support the score’s incorporation into standard care protocols.

Reference:

Ahmed F, Al-Kohlany K, Al-Naggar K, Alnadhari I, Altam AY, Badheeb M. Assessing the Predictive Accuracy of the S.T.O.N.E. Score for Stone-Free Rates in Semirigid Pneumatic Ureteral Lithotripsy: Implications for Validation. Res Rep Urol. 2025;17:139-152

https://doi.org/10.2147/RRU.S515846