title: Use of Procalcitonin Assays to Predict Serious Bacterial Infection in Young Febrile Infants.
abstract: OBJECTIVE
  The procalcitonin (PCT) assay is an accurate screening test for identifying invasive bacterial infection (IBI); however, data on the PCT assay in very young infants are insufficient.
  
  
  OBJECTIVE
  To assess the diagnostic characteristics of the PCT assay for detecting serious bacterial infection (SBI) and IBI in febrile infants aged 7 to 91 days.
  
  
  METHODS
  A prospective cohort study that included infants aged 7 to 91 days admitted for fever to 15 French pediatric emergency departments was conducted for a period of 30 months (October 1, 2008, through March 31, 2011). The data management and analysis were performed from October 1, 2011, through October 31, 2014.
  
  
  METHODS
  The diagnostic characteristics of the PCT assay, C-reactive protein (CRP) concentration, white blood cell (WBC) count, and absolute neutrophil cell (ANC) count for detecting SBI and IBI were described and compared for the overall population and subgroups of infants according to the age and the duration of fever. Laboratory test cutoff values were calculated based on receiver operating characteristic (ROC) curve analysis. The SBIs were defined as a pathogenic bacteria in positive culture of blood, cerebrospinal fluid, urine, or stool samples, including bacteremia and bacterial meningitis classified as IBIs.
  
  
  RESULTS
  Among the 2047 infants included, 139 (6.8%) were diagnosed as having an SBI and 21 (1.0%) as having an IBI (11.0% and 1.7% of those with blood culture (n = 1258), respectively). The PCT assay offered an area under the curve (AUC) of ROC curve similar to that for CRP concentration for the detection of SBI (AUC, 0.81; 95% CI, 0.75-0.86; vs AUC, 0.80; 95% CI, 0.75-0.85; P = .70). The AUC ROC curve for the detection of IBI for the PCT assay was significantly higher than that for the CRP concentration (AUC, 0.91; 95% CI, 0.83-0.99; vs AUC, 0.77; 95% CI, 0.65-0.89; P = .002). Using a cutoff value of 0.3 ng/mL for PCT and 20 mg/L for CRP, negative likelihood ratios were 0.3 (95% CI, 0.2-0.5) for identifying SBI and 0.1 (95% CI, 0.03-0.4) and 0.3 (95% CI, 0.2-0.7) for identifying IBI, respectively. Similar results were obtained for the subgroup of infants younger than 1 month and for those with fever lasting less than 6 hours.
  
  
  CONCLUSIONS
  The PCT assay has better diagnostic accuracy than CRP measurement for detecting IBI; the 2 tests perform similarly for identifying SBI in febrile infants aged 7 to 91 days.
authors.affiliation: Department of Pediatrics, Antoine Béclère University Hospital, Assistance Publique-Hôpitaux de Paris, Clamart, France2INSERM, CESP Centre for Research in Epidemiology and Population Health, Paris-Sud, Paris-Saclay University, Villejuif, France.
authors.forename: Karen
authors.initials: K
authors.lastname: Milcent
authors.affiliation: Pediatric Emergency Department, Paris Descartes University, Necker Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France.
authors.forename: Sabine
authors.initials: S
authors.lastname: Faesch
authors.affiliation: Department of Pediatrics, Hôpital Mère Enfant, Nantes University Hospital, Nantes, France.
authors.forename: Christèle
authors.initials: C
authors.lastname: Gras-Le Guen
authors.affiliation: Pediatric Emergency Unit and Infectious Diseases, Lille University, Lille, France.
authors.forename: François
authors.initials: F
authors.lastname: Dubos
authors.affiliation: INSERM, CESP Centre for Research in Epidemiology and Population Health, Paris-Sud, Paris-Saclay University, Villejuif, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Poulalhon
authors.affiliation: Department of Pediatrics, Poissy Hospital, Poissy, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Badier
authors.affiliation: Department of Pediatrics, Kremlin Bicêtre University Hospital, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Marc
authors.affiliation: Department of Pediatrics, Dupuytren University Hospital, Limoges, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Laguille
authors.affiliation: Department of Pediatrics, Jean Verdier Hospital, Assistance Publique-Hôpitaux de Paris, Paris 13 University, Bondy, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: de Pontual
authors.affiliation: Department of Pediatrics, Sud Francilien Hospital, Corbeil-Essonnes, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Mosca
authors.affiliation: Department of Pediatrics, Centre Hospitalier de Marne La Vallée, Jossigny, France.
authors.forename: Gisèle
authors.initials: G
authors.lastname: Nissack
authors.affiliation: Department of Pediatrics, Créteil Hospital, Créteil, France.
authors.forename: Sandra
authors.initials: S
authors.lastname: Biscardi
authors.affiliation: Department of Paediatric Surgery, Hôpital d'Enfants de La Timone, Marseille, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Le Hors
authors.affiliation: Department of Pediatrics, Rouen University Hospital, Rouen, France.
authors.forename: Ferielle
authors.initials: F
authors.lastname: Louillet
authors.affiliation: Department of Pediatrics, Louis Mourier University Hospital, Assistance Publique-Hôpitaux de Paris, Colombes, France.
authors.forename: Andreea Madalina
authors.initials: AM
authors.lastname: Dumitrescu
authors.affiliation: Pediatric Emergency Unit, Hôpitaux Pédiatriques de Nice, CHU Lenval, Nice, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Babe
authors.affiliation: Assistance Publique-Hôpitaux de Paris, Hôpital Paul Brousse, Virologie, National Reference Laboratory for Maternofetal Rubella Infections, Villejuif, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Vauloup-Fellous
authors.affiliation: INSERM, CESP Centre for Research in Epidemiology and Population Health, Paris-Sud, Paris-Saclay University, Villejuif, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Bouyer
authors.affiliation: Department of Pediatrics, Antoine Béclère University Hospital, Assistance Publique-Hôpitaux de Paris, Clamart, France2INSERM, CESP Centre for Research in Epidemiology and Population Health, Paris-Sud, Paris-Saclay University, Villejuif, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Gajdos
mesh_terms: D019540:Area Under Curve; D001424:Bacterial Infections / Q000097:blood* / Q000175:diagnosis*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D004636:Emergency Service, Hospital; D005260:Female; D005334:Fever / Q000097:blood / Q000382:microbiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007958:Leukocyte Count; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood*; D012372:ROC Curve
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide