Abstract
Introduction
To develop a predictive model incorporating stone volume along with other clinical and radiological factors to predict stone-free (SF) status at ureteroscopy (URS).
Material and methods
Retrospective analysis of patients undergoing URS for kidney stone disease at our institution from 2012 to 2021. SF status was defined as stone fragments < 2 mm at the end of the procedure confirmed endoscopically and no evidence of stone fragments > 2 mm at XR KUB or US KUB at 3 months follow up. We specifically included all non-SF patients to optimise our algorithm for identifying instances with residual stone burden. SF patients were also randomly sampled over the same time period to ensure a more balanced dataset for ML prediction. Stone volumes were measured using preprocedural CT and combined with 19 other clinical and radiological factors. A bagged trees machine learning model with cross-validation was used for this analysis.
Results
330 patients were included (SF: n = 276, not SF: n = 54, mean age 59.5 ± 16.1 years). A fivefold cross validated RUSboosted trees model has an accuracy of 74.5% and AUC of 0.82. The model sensitivity and specificity were 75% and 72.2% respectively. Variable importance analysis identified total stone volume (17.7% of total importance), operation time (14.3%), age (12.9%) and stone composition (10.9%) as important factors in predicting non-SF patients. Single and cumulative stone size which are commonly used in current practice to guide management, only represented 9.4% and 4.7% of total importance, respectively.
Conclusion
Machine learning can be used to predict patients that will be SF at the time of URS. Total stone volume appears to be more important than stone size in predicting SF status. Our findings could be used to optimise patient counselling and highlight an increasing role of stone volume to guide endourological practice and future guidelines.
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Data is confidential and not avaiable for general requests.
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Funding from the Institute for Life Sciences (University of Southampton).
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G. Vigneswaran—Formal analysis and writing—Original draft preparation. R Teh—Data collection, analysis, review & editing. F Ripa—Data collection, editing. A Pietropao—Data collection. S Modi—Review & editing. J Chauhan—Review & editing. B K Somani—Conceptualization, methodology and review & editing.
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The research protocols performed in this study complied with the ethical principles of the Declaration of Helsinki. This retrospective study was approved by HRA, IRAS 324872 (Ethical approval number).
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Vigneswaran, G., Teh, R., Ripa, F. et al. A machine learning approach using stone volume to predict stone-free status at ureteroscopy. World J Urol 42, 344 (2024). https://doi.org/10.1007/s00345-024-05054-6
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DOI: https://doi.org/10.1007/s00345-024-05054-6