title: Vital signs should be maintained as continuous variables when predicting bacterial infections in febrile children.
abstract: OBJECTIVE
  To determine how vital signs such as heart and respiratory rates should be included in prediction models for serious bacterial infections (SBIs) in febrile children.
  
  
  METHODS
  Prospective observational study of 1,750 febrile children aged <16 years, visiting the emergency department of a university hospital; of them 13% (n = 222) had SBI. Common age-specific thresholds of heart and respiratory rates were used to define tachycardia and tachypnea. We compared seven strategies to handle vital signs as predictors of SBI (dichotomized or continuously in various ways).
  
  
  RESULTS
  The dichotomous predictors, namely tachycardia and tachypnea, containing information on the vital sign and age showed limited value to predict the presence of SBI (area under the receiver operating characteristic curve [AUC (ROC)]: 0.53 for heart rate and 0.55 for respiratory rate). In comparison, a model with age as a single continuous predictor resulted in an AUC of 0.58. Models with age and one of the vital signs included continuously showed the highest AUC (heart rate: 0.60 and respiratory rate: 0.63).
  
  
  CONCLUSIONS
  Heart and respiratory rates should be maintained as continuous variables in model development to predict SBI in febrile children, as dichotomization results in information loss and lower predictive ability.
authors.affiliation: Department of Pediatric Ambulatory Care, Erasmus MC-Sophia Children's Hospital, Dr. Molewaterplein 60, Room Sp 1549, 3015 GJ Rotterdam, The Netherlands.
authors.forename: Bart
authors.initials: B
authors.lastname: Spruijt
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Vergouwe
authors.forename: Ruud G
authors.initials: RG
authors.lastname: Nijman
authors.forename: Matthew
authors.initials: M
authors.lastname: Thompson
authors.forename: Rianne
authors.initials: R
authors.lastname: Oostenbrink
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000367:Age Factors; D019540:Area Under Curve; D001424:Bacterial Infections / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital; D005260:Female; D005334:Fever / Q000382:microbiology* / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D009426:Netherlands; D011237:Predictive Value of Tests; D011446:Prospective Studies; D056152:Respiratory Rate / Q000502:physiology*