title: Preoperative nomograms for predicting stone-free rate after extracorporeal shock wave lithotripsy.
abstract: OBJECTIVE
  Extracorporeal shock wave lithotripsy is currently accepted as a first line treatment modality for urolithiasis. In obtaining informed consent it is important to inform patients of the stone-free rate with extracorporeal shock wave lithotripsy before surgery. The present study was performed to develop preoperative nomograms for predicting stone-free rates after extracorporeal shock wave lithotripsy.
  
  
  METHODS
  A total of 435 patients with 507 urinary stones were treated with extracorporeal shock wave lithotripsy with a Dornier Lithotripter D. Patient age, sex, body mass index, number of stone(s) in each treatment, stone length, side and location were evaluated before extracorporeal shock wave lithotripsy, and treatment efficacies were evaluated at 3 months after each session. The treated stones were divided into 2 groups, those in cases that were stone-free with a single extracorporeal shock wave lithotripsy session and those in all other cases. Multivariate analysis was performed using a logistic regression model. The nomograms were developed by repeating the analysis on 200 bootstrap samples.
  
  
  RESULTS
  Stone length, location and number were identified as significant variables on multivariate analysis, and a logistic regression model was developed using these variables. The nomograms predicting stone-free rate at 3 months after single extracorporeal shock wave lithotripsy treatment were finally developed from 200 bootstrap samples. In these nomograms the stone-free probability was highest for solitary proximal ureteral stones less than 5 mm in size (93.8%) and lowest for multiple caliceal stones greater than 21 mm (10.5%).
  
  
  CONCLUSIONS
  This study demonstrated that stone size, location and number are significant predictors of extracorporeal shock wave lithotripsy outcome. We have developed nomograms for predicting the stone-free rate of extracorporeal shock wave lithotripsy, which is useful for counseling patients with urolithiasis before surgery.
authors.affiliation: Department of Urology, Keio University School of Medicine, Tokyo, Japan. cev14660@nyc.odn.ne.jp
authors.forename: Kent
authors.initials: K
authors.lastname: Kanao
authors.forename: Jun
authors.initials: J
authors.lastname: Nakashima
authors.forename: Ken
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Asakura
authors.forename: Akira
authors.initials: A
authors.lastname: Miyajima
authors.forename: Mototsugu
authors.initials: M
authors.lastname: Oya
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohigashi
authors.forename: Masaru
authors.initials: M
authors.lastname: Murai
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007669:Kidney Calculi / Q000473:pathology / Q000628:therapy*; D008096:Lithotripsy; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D011237:Predictive Value of Tests; D016896:Treatment Outcome; D014514:Ureteral Calculi / Q000473:pathology / Q000628:therapy*