Are the current nomograms sufficient to predict shockwave lithotripsy outcomes?

Area of Science:

• Urology
• Nephrology
• Medical Engineering

Background:

• Shock wave lithotripsy (SWL) is a common treatment for upper urinary tract stones.
• Predictive models are crucial for optimizing SWL success rates.
• Current nomograms require validation and comparison for accuracy.

Purpose of the Study:

• To identify factors influencing SWL outcomes in upper urinary tract stones.
• To validate and compare the predictive performance of three existing nomograms: Kim JK, Triple D, and S3HoCKwave.
• To assess the discriminative ability of these nomograms using Area Under the Curve (AUC) analysis.

Main Methods:

• Retrospective review of 580 patients with renal and proximal ureteral stones treated with SWL.
• Multivariate logistic regression analysis to identify independent risk factors for SWL failure.
• Comparison of AUC values for the Kim JK, Triple D, and S3HoCKwave nomograms.

Main Results:

• The overall stone-free rate was 61%, with 24.8% achieving this after one session.
• Independent risk factors for SWL failure included stone location (upper, middle, lower calyx), number of stones, maximum stone diameter, and maximum Hounsfield Unit (HU).
• The AUCs for predicting SWL success were 0.678 (Kim JK), 0.548 (Triple D), and 0.626 (S3HoCKwave), indicating poor discrimination for all three.

Conclusions:

• Stone characteristics such as location, number, diameter, and maximum HU are significant predictors of SWL outcomes.
• The Kim JK, Triple D, and S3HoCKwave nomograms demonstrate limited predictive accuracy for SWL success in upper urinary tract stones.
• Further development of more accurate predictive models for SWL is warranted.