Prediction Model Of Success Rate After Extracorporeal Shock Wave Lithotripsy Of Ureteric Caculus

ObjectiveTo evaluate the clinical outcome of using extracorporeal shock wavelithotripsy(ESWL) in the treatment of ureteric caculus and establish a predictivemodel for the stone-free rate.MethodsA total of514patients with ureteric caculus underwent ESWL monotherapy.All cases were identified by ultrasonography.The results of treatment wereevaluated after3months of follow up.Treatment success was defined ascomplete clearance of the stones with no residual fragments.Several parametersof stone features and patients characteristics including age,gender,BMI,historyof urolithiasis,hematuria,renal colic,stone length,stone width,stonenumber,stone site,stone side,and hydronephrosis were analyzed using univariateand multivariate analyses. Factors found to be significant using the tests werefurther analyzed using multivariate regression analysis,which was performedusing a logistic regression model.ResultsThe overall stone-free rate was84.2%(433/514) with no seriouscomplications being found, while the treatment failed in15.8%(81/514)of thepatients. Using the chis-quaretest and t-test, stone length, stone width, renalcolic and hydronephrosis had a significant impact on the stone-free rate.Multivariate analysis excluded the stone width and stone number from thelogistic regression model, and identified the stone length, hydronephrosis, andrenal colic as the independent factor affecting the outcome of ESWL.A logistic regression model was developed using these variables and toestimate the probability of the outcome of ESWL. The overall accuracy of the model was90.3%, the specificity58.0%and the sensitivity96.3％.ConclusionsStone length, renal colic and hydronephrosis may be important factors ofESWL outcome. Using the regression model we will have an ideal effect toevaluate the probability of complete clearance of the stones.