title: Clinical Nomograms to Predict Stone-Free Rates after Shock-Wave Lithotripsy: Development and Internal-Validation.
abstract: OBJECTIVE
  Shock-wave lithotripsy (SWL) is accepted as the first line treatment modality for uncomplicated upper urinary tract stones; however, validated prediction models with regards to stone-free rates (SFRs) are still needed. We aimed to develop nomograms predicting SFRs after the first and within the third session of SWL. Computed tomography (CT) information was also modeled for constructing nomograms.
  
  
  METHODS
  From March 2006 to December 2013, 3028 patients were treated with SWL for ureter and renal stones at our three tertiary institutions. Four cohorts were constructed: Total-development, Total-validation, CT-development, and CT-validation cohorts. The nomograms were developed using multivariate logistic regression models with selected significant variables in a univariate logistic regression model. A C-index was used to assess the discrimination accuracy of nomograms and calibration plots were used to analyze the consistency of prediction.
  
  
  RESULTS
  The SFR, after the first and within the third session, was 48.3% and 68.8%, respectively. Significant variables were sex, stone location, stone number, and maximal stone diameter in the Total-development cohort, and mean Hounsfield unit (HU) and grade of hydronephrosis (HN) were additional parameters in the CT-development cohort. The C-indices were 0.712 and 0.723 for after the first and within the third session of SWL in the Total-development cohort, and 0.755 and 0.756, in the CT-development cohort, respectively. The calibration plots showed good correspondences.
  
  
  CONCLUSIONS
  We constructed and validated nomograms to predict SFR after SWL. To the best of our knowledge, these are the first graphical nomograms to be modeled with CT information. These may be useful for patient counseling and treatment decision-making.
authors.affiliation: Department of Urology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Jung Kwon
authors.initials: JK
authors.lastname: Kim
authors.affiliation: Department of Urology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Seung Beom
authors.initials: SB
authors.lastname: Ha
authors.affiliation: Department of Urology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Chan Hoo
authors.initials: CH
authors.lastname: Jeon
authors.affiliation: Department of Urology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Jong Jin
authors.initials: JJ
authors.lastname: Oh
authors.affiliation: Department of Urology, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Sung Yong
authors.initials: SY
authors.lastname: Cho
authors.affiliation: Department of Urology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Seung-June
authors.initials: SJ
authors.lastname: Oh
authors.affiliation: Department of Urology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Hyeon Hoe
authors.initials: HH
authors.lastname: Kim
authors.affiliation: Department of Urology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Chang Wook
authors.initials: CW
authors.lastname: Jeong
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000175:diagnosis* / Q000628:therapy*; D008096:Lithotripsy / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015203:Reproducibility of Results; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014545:Urinary Calculi / Q000175:diagnosis* / Q000628:therapy*