Abstract：Objective We investigated predictive factors for success of extracorporeal shock wave lithotripsy (ESWL) for treating single renal stones. Methods We retrospectively reviewed the records 776 patients who had undergone ESWL at this hospital between January 2006 and August 2012 for single renal stones sized from about 7 mm to 20 mm. We excluded patients treated with ureteral catheters and percutaneous nephrostomy; ultimately, only 82 patients fulfilled our inclusion criteria. We classified the success group as those patients whose stones had disappeared or residual stone fragments ＜4 mm on a CT scan and simple X-rays within 3 months after ESWL and the failure group as those patients in whom residual stone fragments＞4 mm after 3 months.We analyzed the differences between the two groups in age, sex, body mass index (BMI), size of stone, stone location, stone laterality, skin-to-stone distance (SSD), density(Hounsfield unit,HU), voltage(kV), and the number of shocks delivered. The statistically significant factors identities were further analyzed by multivariate logistic regression. Results The success group included 63 patients and the failure group included 19. In the univariate analysis, age, sex, BMI,the size of stone, stone location, stone laterality, kV and the number of shocks delivered did not differ significantly between the two groups. Only SSD,and HU were factors influencing success. The results of the multivariate logistic regression analysis showed SSD and HU to be the significant independent predictors of the ESWL stone-free rate. Conclusions The SSD and HU are useful clinical predictive factors of the success of ESWL on single renal stones.
2013, Vol. 24 
