The Association Between Stone Heterogenicity and the Success of Shock Wave Lithotripsy for High Density Upper Urinary Tract Stones: A Muti-Center Prospective Cohort

Objective To prospectively investigate the predictive value of radiological stone heterogenicity for the success of shock-wave lithotripsy (SWL) in patients with high-density upper urinary tract stones. Methods This multi-center prospective study was conducted from June 2020 to December 2023. The radiological stone density index measured by computed tomography (CT) included the mean, standard deviation (SD), and coefficient variation (CV) of the Hounsfield Unit value of stones. The success was defined as no evidence of clinically significant stone fragments (>= 4 mm) on a plain X-ray and ultrasound of the upper urinary tract 1 month after SWL. Binary logistic regression models were used to assess the odds ratios (ORs) and 95% confidence intervals (CIs). Results Finally, 533 patients with high-density upper urinary tract stones were enrolled in this study. There were 68.5% (379/533) patients experienced success after SWL treatment. After adjusted confounding variables, compared with the patients in the lowest quartile of stone density index, the odds ratios (95% CI) for the extreme quartile was 1.42 (0.71, 2.81, P for trend = .443), .03 (.01, .09, P for trend <.001), and .02 (.01, .07, P for trend <.001) for MSD, SD, and CV, respectively. Furthermore, this linear association was confirmed only for SD and CV regardless of gender, body mass index, stone size, and stone location. Conclusion This multi-center prospective study demonstrated a positive association between the stone heterogenicity and the success of SWL in patients with high-density upper urinary tract stones regardless of gender, body mass index, stone size, and stone location. However, this association was not observed in mean stone density.