Evaluating the importance of different computed tomography scan-based factors in predicting the outcome of extracorporeal shock wave lithotripsy for renal stones

Purpose To evaluate the impact of various computed tomography scan-based parameters of renal stones on the outcome of extracorporeal shock wave lithotripsy (ESWL). Materials and Methods We conducted a retrospective study of patients who underwent ESWL for renal stones (sized 5-20 mm) from January 2013 to December 2016. We evaluated body mass index, location of the stone, skin-to-stone distance (SSD), stone attenuation value (SAV), stone diameter, Hounsfield density, stone area, and stone volume. Statistical analysis was done and significance was confirmed by multivariate logistic regression analysis. Results Of the 203 patients 122 (60.1%) had successful clearance of the stone. The presence of a double J stenting, a lower pole location, a higher SAV, higher Hounsfield density, larger stone area, larger stone diameter, and higher stone volume were negative predictors of ESWL outcome. When these parameters were analyzed with multivariate logistic regression analysis, stone location, SSD, and SAV were the only significant independent predictors of the outcome of ESWL. Conclusions Stone location, SSD, and SAV are reliable and strong predictors of ESWL outcome for the treatment of renal stones.