Sihombing AT. et al., 2025: Uncovering New Horizons: Update to Quadruple-D Score to Predict Stone-Free Rate with Advanced Non-invasive Lithotripsy Technology.

Aaron Tigor Sihombing, Zola Wijayanti, Steven Steven, Dicky Stefanus 
Urol Res Pract. 2025 May 21;51(1):38-42. doi: 10.5152/tud.2025.24152 FREE ARTICLE

Abstract

Objective: To evaluate the efficacy of the Quadruple-D scoring system in predicting stone-free rate (SFR) using the newer Generation Piezoelectric lithotripter. Methods: A prospective observational study was conducted from January to December 2023, involving patients who underwent extracorporeal shock wave litho- tripsy (ESWL) for renal stones sized 5-20 mm. Evaluation parameters included stone density, skin-to-stone distance (SSD), stone size (ellipsoid stone volume), and location, with Quadruple-D scores calculated based on predetermined cutoffs. Extracorporeal shock wave lithotripsy sessions utilized the "Piezolith 3000 Plus" lithotripter, and SFR was assessed 4 weeks post-procedure. Statistical analysis included Student's t-test and receiver operating characteristic curve analysis. Results: Of the 40 eligible patients, 75% achieved stone-free status post-ESWL. Stone density and SSD emerged as leading predictors of SFR, with new cut-off values identi- fied. Comparative analysis demonstrated improved predictive power of the Piezolith Q-D score over the previous Quadruple-D score (AUC: 84% and 80% respectively). Although stone location and size also influenced outcomes, their significance varied in this study. Conclusion: The Piezolith Q-D score system exhibits promise in predicting SFR post- ESWL with piezoelectric lithotripters. External validation and larger-scale studies are warranted to establish the scoring system's reliability and applicability across diverse populations.

Comment Hans-Göran Tiselius

The authors formulated a new Quadruple-D-score based on cutoff values from their own series of treatments.
They called the score Piezolith Q-D because all results were obtained with the Piezolith 3000 Plus device. This lithotripter is equipped with three focus sizes, but although the authors emphasized that feature, nothing is mentioned on how they used it.
Surprisingly neither stone size nor stone location were particularly important for the treatment outcome. Why this was so is left unexplained but there certainly were great variations in the series of treatments.
It will be interesting to learn about the results with Piezolith Q-D score in another larger and independent group of patients. Because with their own cutoff values it is difficult to understand what the score really adds.

Hans-Göran Tiselius