A Comparison of the Quadruple-D and Other Nephrolithometry Scoring Systems in Predicting Stone-Free Status After...

To evaluate the predictive performance of the Quadruple-D score in determining stone-free status after percutaneous nephrolithotomy (PCNL) and to compare it with established nephrolithometry systems including the Guy's Stone Score, STONE nephrolithometry, and CROES nomogram.

This retrospective study included 451 patients who underwent PCNL between January 2017 and December 2024. Preoperative parameters including stone volume, density, skin-to-stone distance (SSD), and stone location were assessed to calculate the Quadruple-D score. Outcomes were compared across scoring systems using univariate and multivariate logistic regression and receiver operating characteristic (ROC) analyses.

The overall stone-free rate was 66.7%. In univariate analysis, higher Quadruple-D scores were significantly associated with an increased likelihood of achieving stone-free status (odds ratio [OR] = 2.01; 95% confidence interval [CI]: 1.60-2.54; p < 0.001). Although the CROES score demonstrated the highest area under the curve (AUC), the Quadruple-D score outperformed both the Guy's and STONE scores. In multivariate analysis, only the CROES score remained an independent predictor. Patients with higher Quadruple-D and CROES scores had lower complication rates and higher stone clearance, while higher Guy's and STONE scores were associated with poorer outcomes.

While the CROES score remained the only independent predictor in multivariate analysis, the Quadruple-D score demonstrated promising discriminatory ability in univariate comparisons. Owing to its simplicity and reliance on standard non-contrast computed tomography (CT) imaging, it may serve as a practical risk stratification tool. Prospective, multicenter validation is warranted to confirm its clinical utility in the PCNL setting.