[Analysis of success predictive factors in the treatment of urinary lithiasis by extracorporeal shock wave lithotripsy. patient optimization: ESWL score.].

Objective: Extracorporeal shock wave lithotripsy (ESWL) represents one of the most frequently used methods to treat urinary tract calculi. However, sometimes we do not obtain the fragmentation expected. The aim of this study is to evaluate the parameters that may influence ESWL final results, developing a classification for better patient's selection and outcome optimization.

Methods: 270 patients with renal or ureteral stones were retrospectively reviewed after ESWL treatment, recording both clinical parameters (age, sex, location, laterality, body mass index [BMI]), and CT-Scan parameters (stone size and volume, skin-to-stone distance (SSD), mean and maximal stone density). Cutoff values were determined for each parameter based upon ROC curves, and final score (ESWL score) was calculated based on the number of parameters lower than the cutoff values.

Results: Of the 270 patients treated, 186 (68.8%) were considered as ESWL success, without significant differences between success and failure group. Parameters that showed significant difference after multivariate analysis were: size (cut off: 9.3 mm), volume (237.2 mm3), mean density (951 UH), SSD (133 mm) and BMI (26.9 kg/m2). AUC of ROC curve including all of these parameters, was 0.807. Stone free status was 17.6% for score 0, 25% (score 1), 48.8% (score 2), 74.1% (score 3), 86.3% (score 4) and 92.2% for score 5.

Conclusions: Patient classification before ESWL treatment seems to allow us better selection, improving treatment success.