Comparison of STONE, Guy's Stone, and Seoul National University Renal Stone Complexity (S-ReSC) Scoring Systems for PCNL Monotherapy in Staghorn Stones.

Objective: Accurate evaluation of staghorn stones is crucial for predicting the likeli hood of achieving stone-free status through percutaneous nephrolithotomy. Scoring systems such as the Stone size, Tract length, Obstruction, Number of calyces, Essence of stone density (STONE) score, Guy's Stone score, and Seoul National University Renal Stone Complexity (S-ReSC) score have been developed to quantify stone complexity and guide clinical decision-making.

Methods: This was a prospective comparative study conducted with 52 staghorn calculi patients. Grading of the stone was done by using 3 scoring systems. An imaging study using ultrasound kidneys, ureters, and bladder was performed for early detection of remnant fragments to determine stone-free rate on postoperative day 4. Postoperative complications were categorized by using Clavien-Dindo classification system. Receiver operating characteristic curves were constructed to evaluate the predictive value of 3 stone criteria on the stone-free rate.

Results: According to the Guy's Stone score and S-ReSC score systems, all patients with grade IV and high complexity stones had residual stones by the end of POD 4. In contrast, the STONE criteria reported that 11.1% of high complexity stones were stone free. All 3 stone scoring systems indicated a significant increase in the occurrence of complications with increasing stone complexity. The S-ReSC scoring system exhibited the highest AUC of 0.831, indicating it has superior predictive performance compared to Guy's Stone criteria (AUC: 0.790) and the STONE criteria (AUC: 0.765).

Conclusions: Among the STONE, Guy's Stone, and S-ReSC scoring systems, the S-ReSC scoring system has proven to be the most effective for assessing both SFR and complications.