To develop and validate a prediction model for predicting the failure after extracorporeal shock wave lithotripsy (ESWL) in patients with proximal ureteral stones larger than 1 cm.

The clinical and radiographic data of patients with solitary proximal ureteral stone larger than 1 cm who underwent ESWL from January 2019 to June 2021 were retrospectively analyzed. Clinical data included sex, age, body mass index (BMI) and stone laterality. Radiographic data included stone size, stone density, ureteral wall thickness (UMT), hydronephrosis grade and proximal ureter diameter (PUD). Stone size included maximal craniocaudal (MCD), maximal transverse diameter (MATD), minimal transverse diameter (MITD) and stone volume (SV). Stone density included mean stone density (MESD), maximum stone density (MASD), standard deviation of stone density (SDSD) and variation coefficient of stone density (VCSD). Univariate and multivariate analyses were used to identify the prognostic factors of ESWL failure for proximal ureteral stones larger than 1cm. Multivariable logistic regression model was adopted to built a nomogram. Nomogram performance was determined by its discrimination and calibration.

355 patients in total were divided into two groups as failure (100 cases) and success (255 cases). Univariate analysis showed significant difference in age, stone size (including MCD, MATD, MITD and SV), stone density (including MESD and VCSD), UMT, hytronephrosis grade and PUD between success and failure group. Multivariate analysis showed that age (OR: 1.024 [95%CI: 1.002 to 1.047], P=0.030), MITD (OR: 1.364 [95%CI: 1.020 to 1.825], P=0.036), MESD (OR: 1.003 [95%CI: 1.001 to 1.004], P<0.001), UMT (OR: 1.976 [95%CI: 1.376 to 2.836], P<0.001) and PUD (OR: 1.731 [95%CI: 1.387 to 2.160], P<0.001) were independent predictors of ESWL failure. A nomogram to predict the failure of ESWL with these five predictors was developed. The nomogam showed good calibration and discrimination [area under the ROC curve was 0.881 (95%CI: 0.844 to 0.917)].

Based on age, MITD, MESD, UMT and PUD, the nomogram showed good prediction value, which provided reference to screening the suitable patients with proximal ureteral stone larger than 1 cm for ESWL treatment.