Utility of the Guy’s Stone Score on real world outcomes of suction mini-PCNL in 1527 adult patients with normal collecting system anatomy A prospective multicenter study from the EAU section of Endourology and Asian Urological Society of Endoluminal Surgery and Technology collaboration

BACKGROUND: Guy’s Stone Score (GSS) has proven to be the most reliable and valuable tool for predicting the success rate and potential complications after percutaneous nephrolithotomy (PCNL) This study aims to assess the impact of GSS on perioperative outcomes, complications and stone-free rates (SFR) in adult patients undergoing suction mini-percutaneous (SM)-PCNL for kidney stone(s). METHODS: Data from 1527 adult patients with normal renal anatomy who underwent prone or supine SM-PCNL across 21 countries were analyzed. Patients were stratified by GSS (1-4) based on preoperative CT imaging. The primary outcome was 30-day SFR, assessed by non-contrast CT, defined as zero fragment. Secondary outcomes included peri-and postoperative complications. Multivariate analysis identified predictors of SFR and complications. RESULTS: Despite increased complexity, SM-PCNL was frequently utilized for GSS 3 and 4 cases, often requiring multiple tracts and advanced access techniques. Complication rates, including bleeding and infectious events, were low but significantly higher in GSS 3 and 4 groups. SFR decreased with increasing GSS, with GSS 1 achieving the highest rates and GSS 4 the lowest. Multivariate analysis identified stone volume (OR 0.96), and GSS 2 (OR 0.53), 3 (OR 0.27) and 4 (OR 0.46) as independent predictors of lower odds of zero residual fragment compared to GSS 1, while sheath size 16-18 Fr (OR 1.72) and <18 Fr (OR 4.48) with higher odds compared to sheath size <16 Fr. GSS 2 (OR 2.22), 3 (OR 4.97) and 4 (OR 4.01) compared to GSS 1 and mechanical lithotripsy (OR 1.65) were associated with higher odds of all complications compared to laser lithotripsy. CONCLUSIONS: GSS effectively predicts perioperative outcomes following suction mini-PCNL. Increasing stone complexity is associated with reduced SFR and higher complication rates, underscoring the importance of preoperative risk stratification, tailored surgical planning and a proper informed consent for the patient in complex cases.