title: Validation of a nomogram predicting complications after esophagectomy for cancer.
abstract: BACKGROUND
  A nomogram has been developed recently in order to predict the occurrence and severity of postoperative complications after esophagectomy for cancer. In the present study, we externally validated this nomogram in a new cohort of patients who underwent esophagectomy for cancer in a different high-volume center.
  
  
  METHODS
  An independent dataset of 777 patients who underwent esophagectomy for cancer was used for validation. The discriminatory capability of the nomogram was determined by using the concordance index (C statistic). Calibration was evaluated by comparing the observed with the expected number of patients with complications, as predicted by the original nomogram across patients with different risk profiles. We also examined whether adjusting the value of the original coefficients of the predictors or adding new predictors would improve the fit of the nomogram.
  
  
  RESULTS
  Discrimination of the original nomogram was similar in the validation cohort: the C statistic hardly decreased from 0.65 in the original cohort to 0.64 in the validation cohort. Observed and expected number of patients with complications were in close agreement, reflecting a good calibration (p = 0.84). Reestimation of the coefficients in the validation cohort did not lead to any significant changes of the original nomogram values.
  
  
  CONCLUSIONS
  External validation of a nomogram predicting the occurrence and severity of complications after esophagectomy showed that the model is applicable in other high-volume hospitals. Nevertheless, preoperative prediction of complications in individual patients remains difficult, most likely due to the complexity of mechanisms causing these complications.
authors: Department of Surgery, Erasmus Medical Center, Rotterdam, The Netherlands. b.grotenhuis@erasmusmc.nl
authors: Brechtje A
authors: BA
authors: Grotenhuis
authors: Pieter
authors: P
authors: van Hagen
authors: Johannes B
authors: JB
authors: Reitsma
authors: Sjoerd M
authors: SM
authors: Lagarde
authors: Bas P L
authors: BP
authors: Wijnhoven
authors: Mark I
authors: MI
authors: van Berge Henegouwen
authors: Hugo W
authors: HW
authors: Tilanus
authors: J Jan B
authors: JJ
authors: van Lanschot
mesh_terms: D000230:Adenocarcinoma / Q000601:surgery*; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000601:surgery*; D004938:Esophageal Neoplasms / Q000601:surgery*; D016629:Esophagectomy / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D011183:Postoperative Complications / Q000453:epidemiology; D011379:Prognosis; D012720:Severity of Illness Index