Percutaneous nephrolithotomy (PCNL) is considered the first-line treatment modality for high-volume renal calculi. Recently, several nephrolithometry scoring systems based on preoperative stone and patient features have been proposed to describe and predict stone-free rate (SFR) and complications.
The aim of this study is to investigate the predictive factors of surgical outcomes of PCNL and to compare accuracy of the Guy’s stone score, S.T.O.N.E. nephrolithometry, CROES nomogram and S-ReSC score.
We reviewed retrospectively the surgical outcomes recorded consecutively and imaging data of preoperative computed tomography scans of patients who had undergone PCNL from 2013 to 2016 . Patients with asymptomatic residual fragments <4 mm were considered stone-free. The Guy’s stone score, S.T.O.N.E. nephrolithometry, CROES nomogram , S-ReSC score and other prognostic factors were assessed using univariate and multivariate statistical analyses.
A total of 157 PCNLs were reviewed. The overall stone-free rate was 59 % with a complication rate of 22 %. Stone Burden < 542mm3 is significantly associated with stone-free rate (SFR)(p=0.001). On Univariate analysis, all the scoring systems were identified as significant factors in terms of SFR. The Guy’s Stone Score, the CROES score and the S-ReSC score were associated with complications (p<0.02). Stone Burden>861 mm3 is significantly associated with complications(p = 0,01) .The multivariate logistic regression analysis showed that the STONE score and the CROES were identified as significant factors in terms of SFR (p<0.03). The area under the receiver operating characteristic (ROC) curves for the Guy’s, S.T.O.N.E., and S-ReSC scores and stone burden showed good results (0.674, 0.762, 0.710, and 0.737, respectively).
Of the four scoring systems, the STONE and the CROES scores were significant predictive factors for SFR after PCNL in multivariate logistic regression analysis. These results could be due to study of stones characteristics and kidneys anatomy.