Preoperation Predictors Of Stone-Free Rate In Patients Undergoing Percutaneous Nephroli Thotripsy

Background and ObjectivePercutaneous nephrolithotripsy (PCNL) is the treatment of choice for patients with extensive stone burden or stones refractory to extracorporeal shock wave lithotripsy. However, little is known about factors predicting unfavourable outcome in terms of stone-free rate.This study was performed to investigate the prognostic factors associated with the success rate of PCNL and try to develop a preoperative nomograms for predicting stone-free rate after PCNL.MethodsBetween January 2008 and December 2010, a total of 428 patients (286 men and 142 women; range 19-74years; mean age 41.24±10.37 years) with complex kidney stones were treated by PCNL with pneumatic and ultrasonic power under B-type ultrasound guidance. All cases were identified by KUB/TVU, Type B ultrasonic and computed temgraphy. Patient age, sex, height, weight, body mass index, duration of disease, stone burden, number, side, location, pre-existent urinary tract infection, pre-existent hydronephrosis and previous kidney surgery were evaluated before PCNL, and treatment efficacies were evaluated at hospital discharge. Treatment success was defined as complete clearance of the stones or the residual fragments smaller than 4 mm. The stone-free rate was correlated with stone features and patient characteristics using the chi square test and t-test. Factors found to be significant using the tests were further analyzed using multivariate regression analysis, which was performed using a logistic regression model.ResultsUsing the chi square test and t-test, stone burden, number and location had a significant impact on the stone-free rate(P<0.05). Multivariate analysis excluded stone burden and stone number from the logistic regression model while the stone location maintained statistically significant effect on success rate, indicating that it was a independent predictor.ConclusionThis study demonstrated that stone location was a significant predictor of PCNL outcome, which is useful for counseling patients with urolithiasis before surgery.