title: Development and Internal Validation of a Classification System for Predicting Success Rates After Endoscopic Combined Intrarenal Surgery in the Modified Valdivia Position for Large Renal Stones.
abstract: OBJECTIVE
  To identify preoperative predictors and to develop a classification system for predicting success rate after endoscopic combined intrarenal surgery (ECIRS) in the modified Valdivia position for renal stone treatment.
  
  
  METHODS
  We retrospectively analyzed 329 consecutive, single-session ECIRS procedures undertaken in the modified Valdivia position to treat renal stones. The successful status after surgery was determined at 1 month postoperatively using noncontrast computed tomography and was defined as the absence of stones or residual fragments measuring <4 mm. The preoperative factors analyzed included the stone statuses, which were determined by noncontrast computed tomography, and the patients' characteristics. A multivariate logistic regression model with backward selection was used to evaluate the relationships between the preoperative factors and a successful status after ECIRS, and a classification system was developed to predict a stone-free status based on the preoperative factors.
  
  
  RESULTS
  The overall successful outcome rate was 65.3%. Multivariate analysis determined 2 independent predictors of ECIRS outcomes, namely, the stone surface areas (P = .001) and the number of involved calyces (P = .001). These parameters were used to develop the classification system for predicting the successful status after ECIRS.
  
  
  CONCLUSIONS
  Stone surface areas and the number of involved calyces independently predicted the successful status after ECIRS. This is the first study to identify the independent predictors and develop a classification table for predicting success rates after ECIRS in the modified Valdivia position.
authors.affiliation: Department of Urology, Ohguchi Higashi General Hospital, Yokohama, Japan.
authors.forename: Shinnosuke
authors.initials: S
authors.lastname: Kuroda
authors.affiliation: Department of Urology, Ohguchi Higashi General Hospital, Yokohama, Japan; Department of Urology, Yokohama City University Hospital, Yokohama, Japan. Electronic address: pug_daikichi@yahoo.co.jp.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ito
authors.affiliation: Department of Biostatistics and Epidemiology, Yokohama City University Medical Center, Yokohama, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Sakamaki
authors.affiliation: Department of Urology, Ohguchi Higashi General Hospital, Yokohama, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Tabei
authors.affiliation: Department of Urology, Yokohama City University Hospital, Yokohama, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kawahara
authors.affiliation: Department of Urology, Ohguchi Higashi General Hospital, Yokohama, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Terao
authors.affiliation: Department of Urology, Ohguchi Higashi General Hospital, Yokohama, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fujikawa
authors.affiliation: Department of Urology, Yokohama City University Hospital, Yokohama, Japan.
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Makiyama
authors.affiliation: Department of Urology, Yokohama City University Hospital, Yokohama, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yao
authors.affiliation: Department of Urology, Ohguchi Higashi General Hospital, Yokohama, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Matsuzaki
mesh_terms: D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging / Q000601:surgery*; D007670:Kidney Calices / Q000000981:diagnostic imaging / Q000601:surgery; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D011379:Prognosis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D018666:Ureteroscopy / Q000379:methods*