Login to Access Video or Poster Abstract: MP68-20
Sources of Funding: None

Introduction

Several scoring systems have been developed to assess stone complexity in patients undergoing percutaneous nephrolithotomy (PCNL) which may help in preoperative patient counselling, surgical planning and stratification of outcomes . Their precise role is yet to be established; moreover, the associated interobserver variability may lead to poor reproducibility of these scoring systems. The present study aims at assessing the interobserver variability among the surgeons performing the PCNL and compares with scoring done by the radiologists for the Guy’s stone score and S.T.O.N.E. nephrolithometry score.

Methods

Patients undergoing PCNL between February 2016 and September 2016 were prospectively enrolled. Preoperative computed tomography was done in all patients. The Guy’s stone score and S.T.O.N.E. nephrolithometry score were independently calculated by 8 surgeons (5 consultants and 3 residents) and 4 radiologists (2 consultants and 2 residents). All patients underwent either standard PCNL or mini PCNL by one of the 5 surgeons (consultants). Consistency among the scores was assessed using Cronbach’s alpha. Receiver operative characteristic (ROC) curve was used to predict the stone free rate (SFR) using average scores of the surgeons as well as the radiologists individually.

Results

157 patients underwent PCNL during this period. The SFR was 71.3% (112/157 patients). Cronbach’s alpha among the 8 surgeons and 4 radiologists was 0.957 and 0.994 respectively. ROC curve revealed that the S.T.O.N.E. nephrolithometry score of the surgeons (AUC = 0.806) as well as the radiologists (AUC = 0.810) had better predictive accuracy as compared to Guy’s stone score by surgeons (AUC = 0.738) and the radiologists (AUC = 0.747).

Conclusions

The S.T.O.N.E. nephrolithometry score has superior reproducibility among the surgeons and radiologists and is a better indicator of SFR compared to the Guy’s stone score.

Funding

None