title: Polytomous regression did not outperform dichotomous logistic regression in diagnosing serious bacterial infections in febrile children.
abstract: OBJECTIVE
  To compare polytomous and dichotomous logistic regression analyses in diagnosing serious bacterial infections (SBIs) in children with fever without apparent source (FWS).
  
  
  METHODS
  We analyzed data of 595 children aged 1-36 months, who attended the emergency department with fever without source. Outcome categories were SBI, subdivided in pneumonia and other-SBI (OSBI), and non-SBI. Potential predictors were selected based on previous studies and literature. Four models were developed: a polytomous model, estimating probabilities for three diagnostic categories simultaneously; two sequential dichotomous models, which differed in variable selection, discriminating SBI and non-SBI in step 1, and pneumonia and OSBI in step 2; and model 4, where each outcome category was opposed to the other two. The models were compared with respect to the area under the receiver-operating characteristic curve (AUC) for each of the three outcome categories and to the variable selection.
  
  
  RESULTS
  Small differences were found in the variables that were selected in the polytomous and dichotomous models. The AUCs of the three outcome categories were similar for each modeling strategy.
  
  
  CONCLUSIONS
  A polytomous logistic regression analysis did not outperform sequential and single application of dichotomous logistic regression analyses in diagnosing SBIs in children with FWS.
authors.affiliation: Department of Pediatrics, Sophia Children's Hospital, Erasmus MC, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands.
authors.forename: Jolt
authors.initials: J
authors.lastname: Roukema
authors.forename: Rhiannon B
authors.initials: RB
authors.lastname: van Loenhout
authors.forename: Ewout W
authors.initials: EW
authors.lastname: Steyerberg
authors.forename: Karel G M
authors.initials: KG
authors.lastname: Moons
authors.forename: Sacha E
authors.initials: SE
authors.lastname: Bleeker
authors.forename: Henriëtte A
authors.initials: HA
authors.lastname: Moll
mesh_terms: D001424:Bacterial Infections / Q000150:complications / Q000175:diagnosis*; D002675:Child, Preschool; D003627:Data Interpretation, Statistical; D003661:Decision Support Techniques; D004636:Emergency Service, Hospital; D005260:Female; D005335:Fever of Unknown Origin / Q000382:microbiology*; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D012044:Regression Analysis; D012307:Risk Factors