title: Diagnostic value of procalcitonin in well-appearing young febrile infants.
abstract: OBJECTIVE
  Procalcitonin (PCT) has been introduced in many European protocols for the management of febrile children. Its value among young, well-appearing infants, however, is not completely defined. Our objective was to assess its performance in diagnosing serious bacterial infections and specifically invasive bacterial infections (IBIs) in well-appearing infants aged <3 months with fever without source (FWS).
  
  
  METHODS
  Well-appearing infants aged <3 months with FWS admitted to 7 European pediatric emergency departments were retrospectively included. IBI was defined as the isolation of a bacterial pathogen in blood or cerebrospinal fluid culture.
  
  
  RESULTS
  We included 1112 infants who had PCT measured and a blood culture performed. IBI was diagnosed in 23 cases (2.1%). In the multivariate analysis including clinical and laboratory data, PCT was the only independent risk factor for IBI (odds ratio 21.69; 95% confidence interval [CI] 7.93-59.28 for PCT ≥ 0.5 ng/mL). Positive likelihood ratios for PCT ≥ 2 ng/mL and C-reactive protein (CRP) >40 mg/L were 11.14 (95% CI 7.81-15.89) and 3.45 (95% CI 2.20-5.42), respectively. Negative likelihood ratios for PCT <0.5 ng/mL and CRP <20 mg/L were 0.25 (95% CI 0.12-0.55) and 0.41 (95% CI 0.22-0.76). Among patients with normal urine dipstick results and fever of recent onset, areas under the receiver operator characteristic curve for PCT and CRP were 0.819 and 0.563, respectively.
  
  
  CONCLUSIONS
  Among well-appearing young infants with FWS, PCT performs better than CRP in identifying patients with IBIs and seems to be the best marker for ruling out IBIs. Among patients with normal urine dipstick results and fever of recent onset, PCT remains the most accurate blood test.
authors.affiliation: Pediatric Emergency Department, Cruces Univeristy Hospital, Plaza de Cruces, 48.902 Barakaldo, Spain. borja.gomezcortes@osakidetza.net
authors.forename: Borja
authors.initials: B
authors.lastname: Gomez
authors.forename: Silvia
authors.initials: S
authors.lastname: Bressan
authors.forename: Santiago
authors.initials: S
authors.lastname: Mintegi
authors.forename: Liviana
authors.initials: L
authors.lastname: Da Dalt
authors.forename: Daniel
authors.initials: D
authors.lastname: Blazquez
authors.forename: Izaskun
authors.initials: I
authors.lastname: Olaciregui
authors.forename: Mercedes
authors.initials: M
authors.lastname: de la Torre
authors.forename: Miriam
authors.initials: M
authors.lastname: Palacios
authors.forename: Paola
authors.initials: P
authors.lastname: Berlese
authors.forename: Aitor
authors.initials: A
authors.lastname: Ruano
mesh_terms: D001424:Bacterial Infections / Q000150:complications* / Q000175:diagnosis*; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D005260:Female; D005335:Fever of Unknown Origin / Q000097:blood* / Q000209:etiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011498:Protein Precursors / Q000097:blood*; D012189:Retrospective Studies
chemical_list: C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide