# B.T.C.H. nephrolithometry score: a novel scoring system to predict stone-free rate and complexity for ultrasound-guided percutaneous nephrolithotomy

## TL;DR

A new scoring system called B.T.C.H. nephrolithometry improves predictions for kidney stone removal success and procedure complexity.

## Contribution

Introduces a novel scoring system that better predicts stone-free rates and procedure complexity in ultrasound-guided percutaneous nephrolithotomy.

## Key findings

- The B.T.C.H. score achieved a 90.9% accuracy in predicting stone-free rates.
- It outperformed existing systems like GSS and S.T.O.N.E. in predictive accuracy.
- The score correlated positively with operative time, number of tracts, and postoperative CDC scores.

## Abstract

The existing scoring systems for percutaneous nephrolithotomy fail to adequately consider the influence of renal anatomy, leading to limited predictive accuracy. This study introduces and validates a novel B.T.C.H. nephrolithometry score, designed to better predict stone-free rates and complexity for ultrasound-guided percutaneous nephrolithotomy.

B.T.C.H. nephrolithometry score evaluates four variables including stone burden, type of renal pelvis, calyces involved, and hydronephrosis. 134 patients who underwent ultrasound-guided percutaneous nephrolithotomy at Beijing Tsinghua Changgung Hospital were retrospectively analyzed. The inter-observer agreement was assessed using the linearly weighted kappa coefficient. The accuracy in predicting the stone-free rate was evaluated using receiver operating characteristic curve analysis. Spearman’s correlation analysis and Kendall’s W test were employed to examine the correlation between the scores of each scoring system and operative time, the number of tracts and CDC scores.

The overall stone-free rate was 52.99%. The stone-free rates in low (4–8 points), medium (9–12 points), and high (13–15 points) B.T.C.H. scores were 91.9, 24.6, and 0%, respectively. The B.T.C.H. nephrolithometry score had an AUC of 0.909 for predicting stone-free rate, outperforming both the GSS (AUC = 0.761) and the S.T.O.N.E. nephrolithometry score (AUC = 0.763). The B.T.C.H. nephrolithometry score were positively correlated with operative time, the number of tracts and CDC scores.

B.T.C.H. nephrolithometry score is a suggested novel scoring system for ultrasound-guided percutaneous nephrolithotomy, which had superior prediction of stone-free rate and positive correlation with operative time, the number of tracts, and postoperative CDC scores.