Uncovering New Horizons: Update to Quadruple-D Score to Predict Stone-Free Rate with Advanced Non- invasive Lithotripsy Technology

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.

Cite this article as: Sihombing AT, Wijayanti!Z, Steven S, Stefanus D. Uncovering new horizons: Update to quadruple-D score to predict stone-free rate with advanced non-invasive lithotripsy technology. Urol Res Pract. 2025;51(1):38-42.