title: External Validation of Models for Prediction of Lymph Node Metastasis in Urothelial Carcinoma of the Bladder.
abstract: OBJECTIVE
  To externally validate models to predict LN metastsis; Karakiewicz nomogram, clinical nodal staging score (cNSS), and pathologic nodal staging score (pNSS) using a different cohort.
  
  
  METHODS
  Clinicopathologic data from 500 patients who underwent radical cystectomy and pelvic lymphadenectomy were analyzed. The overall predictive values of models were compared with the criteria of overall performance, discrimination, calibration, and clinical usefulness.
  
  
  RESULTS
  Presence of pN+ stages was recorded in 117 patients (23.4%). Agreement between clinical and pathologic stage was noted in 174 (34.8%). Based on Nagelkerke's peudo-R2 and brier score, pNSS demonstrated best overall performance. Area under the receiver operating characteristics curve, showed that pNSS had the best discriminatory ability. In all models, calibration was on average correct (calibration-in-the-large coefficient = zero). On decision curve analysis, pNSS performed better than other models across a wide range of threshold probabilities.
  
  
  CONCLUSIONS
  When compared to pNSS, current precystectomy models such as the Karakiewicz nomogram and cNSS cannot predict the probability of LN metastases accurately. The findings suggest that the application of pNSS to Asian patients is feasible.
authors.affiliation: Department of Urology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Ja Hyeon
authors.initials: JH
authors.lastname: Ku
authors.affiliation: Department of Urology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Myong
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Urology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Seok-Soo
authors.initials: SS
authors.lastname: Byun
authors.affiliation: Department of Urology, SMG-SNU Boramae Medical Center, Seoul, Korea.
authors.forename: Hyeon
authors.initials: H
authors.lastname: Jeong
authors.affiliation: Department of Urology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Cheol
authors.initials: C
authors.lastname: Kwak
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 Bundang Hospital, Seongnam, Korea.
authors.forename: Sang Eun
authors.initials: SE
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002295:Carcinoma, Transitional Cell / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009367:Neoplasm Staging; D012372:ROC Curve; D001749:Urinary Bladder Neoplasms / Q000473:pathology*; D055815:Young Adult