title: Internal and External Validation of a multivariable Model to Define Hospital-Acquired Pneumonia After Esophagectomy.
abstract: BACKGROUND
  Pneumonia is an important complication following esophagectomy; however, a wide range of pneumonia incidence is reported. The lack of one generally accepted definition prevents valid inter-study comparisons. We aimed to simplify and validate an existing scoring model to define pneumonia following esophagectomy.
  
  
  METHODS
  The Utrecht Pneumonia Score, comprising of pulmonary radiography findings, leucocyte count, and temperature, was simplified and internally validated using bootstrapping in the dataset (n = 185) in which it was developed. Subsequently, the intercept and (shrunk) coefficients of the developed multivariable logistic regression model were applied to an external dataset (n = 201) RESULTS: In the revised Uniform Pneumonia Score, points are assigned based on the temperature, the leucocyte, and the findings of pulmonary radiography. The model discrimination was excellent in the internal validation set and in the external validation set (C-statistics 0.93 and 0.91, respectively); furthermore, the model calibrated well in both cohorts.
  
  
  CONCLUSIONS
  The revised Uniform Pneumonia Score (rUPS) can serve as a means to define post-esophagectomy pneumonia. Utilization of a uniform definition for pneumonia will improve inter-study comparability and improve the evaluations of new therapeutic strategies to reduce the pneumonia incidence.
authors.affiliation: Department of Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands.|Department of Surgery, University Medical Center Utrecht, Heidelberglaan 100, 3508, GA, Utrecht, The Netherlands.
authors.forename: Teus J
authors.initials: TJ
authors.lastname: Weijs
authors.affiliation: Department of Surgery, University Medical Center Utrecht, Heidelberglaan 100, 3508, GA, Utrecht, The Netherlands. m.f.j.seesing@umcutrecht.nl.|Department of Surgical Oncology, UMC Utrecht, Heidelberglaan 100, 3508, GA, Utrecht, The Netherlands. m.f.j.seesing@umcutrecht.nl.
authors.forename: Maarten F J
authors.initials: MF
authors.lastname: Seesing
authors.affiliation: Department of Surgery, University Medical Center Utrecht, Heidelberglaan 100, 3508, GA, Utrecht, The Netherlands.|Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Peter S N
authors.initials: PS
authors.lastname: van Rossum
authors.affiliation: Department of Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands.
authors.forename: Marijn
authors.initials: M
authors.lastname: Koëter
authors.affiliation: Department of Surgery, University Medical Center Utrecht, Heidelberglaan 100, 3508, GA, Utrecht, The Netherlands.
authors.forename: Pieter C
authors.initials: PC
authors.lastname: van der Sluis
authors.affiliation: Department of Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands.
authors.forename: Misha D P
authors.initials: MD
authors.lastname: Luyer
authors.affiliation: Department of Surgery, University Medical Center Utrecht, Heidelberglaan 100, 3508, GA, Utrecht, The Netherlands.
authors.forename: Jelle P
authors.initials: JP
authors.lastname: Ruurda
authors.affiliation: Department of Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands.
authors.forename: Grard A P
authors.initials: GA
authors.lastname: Nieuwenhuijzen
authors.affiliation: Department of Surgery, University Medical Center Utrecht, Heidelberglaan 100, 3508, GA, Utrecht, The Netherlands. r.vanhillegersberg@umcutrecht.nl.
authors.forename: Richard
authors.initials: R
authors.lastname: van Hillegersberg
mesh_terms: D000328:Adult; D001831:Body Temperature; D003428:Cross Infection / Q000000981:diagnostic imaging / Q000453:epidemiology*; D016629:Esophagectomy; D005260:Female; D006801:Humans; D015994:Incidence; D007958:Leukocyte Count; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011014:Pneumonia / Q000000981:diagnostic imaging / Q000453:epidemiology*; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000453:epidemiology*
keywords: Esophageal carcinoma; Esophagectomy; Pneumonia