The Analysis Of Extracorporeal Shock-wave Lithotripsy Of Ureteric Stones And The Establishment Of Predictive Model

Objective:To study and define the factors that have a significant impact on the stone free rate after ESWL of ureteric calculi,establish a preoperative forecasting model and evaluate the efficiency.patients and Methods:Between May 2005 and November 2005,664patients with ureteric calculi who underwent ESWL in the Second Affiliated Hospital of Tianjin Medical University were included.The Information of history,signs,imaging features were recorded.Close follow-up were made and the results were recorded. When ESWL proceeding,using ultrasound to assess fragmentation dynamically. Patients were reviewed 2,4weeks and 3 months using KUB and renal ultrasound to assess fragmentation.Success was defined as the absence of residual stones within 3months.We select factors according to the references and the actual situation. Chi-square test,t-test were employed in the univariate analysis.Logistic regression was employed in the multivariate analysis,and a Logistic regression predictive model can be created.Hosmer-Lemeshow Test was employed to evaluate the goodness of fit.Using classification table to evaluate the efficiency of the model predictions. Randomly select 200 patients with ureteral stones who underwent ESWL treatment as the test group to perform reevaluation.Results:1.Univariate analysis showed:age,sex,stone side did not affect the outcome(P＞0.05).The Stone location,stone number,stone size,course,renal colic, and the degree of hydronephrosis affect the ESWL efficacy of ureteral stones,a significant difference in statistics(P＜0.01).Multivariate analysis showed that:The location of the stone,stone number,stone size,course,renal colic are independent factors impact on ESWL out come of ureteral stones,the value of the odds ratios (95%confidence interval) being 2.440(1.330,4.473),8.664(1.677,44.768),48.237 (10.183,228.512),4.708(1.426,15.550),0.167(0.058,0.480).2.We established preoperative predictive model.Hosmer-Lemeshow test showed the model fit the data well.When we chose 0.5 as the cut value,the performence of the model reveals a sensitivity(accurately forecast emptying) of 99.4%and the specificity(not accurately predict emptying) 20%,positive predictive value of 96.9%,negative predictive value of 55.6%.the overall accuracy of 96.4%.The reevaluation performed by test group reveals a sensitivity of 98.4%and the specificity 27.3%,positive predictive value of 95.9%,negative predictive value of 50%.the overall accuracy of 94.5%.Conclusion:The location of the stone,stone number,stone size,course,renal colic are independent factors impact on the stone free rate of ESWL.The degree of hydronephrosis was not included in the predictive model,but still has clinical importance.The model fit the data well,independent factors were include in the model.This study confirmed that the model can predict ESWL out com of ureteral calculi.The predictive model is useful for counseling patients with urolithiasis before surgery.