Evaluation and comparison of SHA.LIN, S.T.O.N.E nephrolithometry scoring system and Guy's stone score in predicting the accuracy of the percutaneous nephrolithotomy(PCNL) outcomes

Abstract

Objective To compared the accuracy of the SHA.LIN, S. T.O.N.E. nephrolithometry scoring system and Guy's stone score in the same cohort and to determine which was most predictive of percutaneous nephrolithotomy(PCNL) outcomes. Methods A retrospective analysis was conducted of clinical data of 123 patients with nephrolithiasis undergoing PCNL from June 2011 and June 2015 in two hospitals. The SHA.LIN nephrolithometry score , the S. T.O.N.E. score and the Guy's stone score based on preoperative computerized tomography images were calculated. A single observer reviewed all images and assigned scores. Logistic and linear regression analysis were performed and Receiver operating characteristic (ROC) curves were drawn to determine the most predictive scoring system. Results The stone free rate was 76.4%(94/123) and postoperative complications occurred in 33(26.8%) cases.In stone-free patients vs. those with residual stones the mean SHA.LIN nephrolithometry score was 8.2 vs. 11.8, the mean S. T.O.N.E. score was 7.3 vs. 8.6 and the mean Guy's stone score was 2.4 vs.3.0 (each P=0.000). Logistic regression revealed that SHA.LIN nephrolithometry score, S. T.O.N.E. score and the Guy's stone score were significantly associated with stone-free status (each P=0.000) and postoperative complications(P<0.05). The SHA.LIN nephrolithometry score was associated with operation time and estimated blood loss (P=0.000 and 0.011). S. T.O.N.E. score and Guy's stone score were associated with operation time (P=0.000 and 0.006, respectively). All scoring systems did not predict length of stay. There was significant difference in the areas under the curves(AUC) for the SHA.LIN vs. S. T.O.N.E. scoring system [0.924(95%CI 0.874-0.975)vs. 0.795(95%CI 0.698-0.891), P=0.001] and for the SHA.LIN nephrolithometry score vs Guy's stone score [0.924(95%CI 0.874-0.975) vs. 0.701(95%CI 0.592-0.811), P<0.000]. Conclusion All scoring systems have comparable accuracies and the predictive accuracy of the SHA.LIN scoring system is more precise than the S. T.O.N.E. score and the Guy's score in predicting post-PCNL stonefree status and postoperative complications. Key words: Kidney calculi; Nephrostomy, percutaneous; Classification; Prognosis; Perioperative period