Comparison of Guy and Clinical Research Office of the Endourological Society Nephrolithometry Scoring Systems for Predicting Stone-Free Status and Complication Rates After Percutaneous Nephrolithotomy: A Single Center Study with 437 Cases

Purpose: To compare the Guy and Clinical Research Office of the Endourological Society (CROES) scoring systems in predicting postpercutaneous nephrolithotomy (PCNL) stone-free rate and complications. Patients and Methods: A total of 437 patients who underwent PCNL for renal stones were included in the recent retrospective study. All stones were evaluated with CT preoperatively. Mean stone diameter was 701.52510.65mm(2). Guy and CROES nephrolithometry scores were calculated for each patient, and their correlation with stone-free status, operative and fluoroscopy time, and length of hospital stay was evaluated. Post-PCNL stone status was evaluated with plain radiography of the kidneys, ureters, and bladder. Postoperative complications were graded according to the modified Clavien classification, and the correlation of both scoring systems with postoperative complications was also investigated. Results: The mean Guy grade was 2.28 +/- 1.12, and the mean CROES score was 196.92 +/- 65.89. The overall stone-free rate was 75.1%. There was a significant correlation between the Guy stone score (GSS) and CROES score and stone-free status (P<0.001, P<0.001). Also, both scoring systems were correlated with operative time (P<0.001, P<0.001) and length of hospital stay (P=0.002, P=0.01). The overall complication rate was 34.6%, with most being modified Clavien grade I and grade II. Both scoring systems were significantly correlated with complication rates. Regression analysis showed that both scoring systems were significantly associated with stone-free rates, estimated blood loss (EBL) (>250mL), and operative time. Conclusion: Both GSS and CROES nomograms had comparable accuracies in predicting post-PCNL stone-free status. Different from the previous reports, our results showed that both nomograms were predictive of overall complications, EBL, and operative time.