title: C-reactive protein, procalcitonin and the lab-score for detecting serious bacterial infections in febrile children at the emergency department: a prospective observational study.
abstract: BACKGROUND
  C-reactive protein (CRP) and procalcitonin (PCT) are useful diagnostic tools to estimate the risk of serious bacterial infection (SBI) in febrile children at the emergency department (ED). The Lab-score combines these 2 biomarkers with urinalysis in an easy to use validated model. Kinetics of inflammatory markers suggests a differentiating role of duration of disease.
  
  
  OBJECTIVE
  : Appraisal of the diagnostic role of CRP and PCT in febrile children at risk of SBI, determining the differentiating value of duration of fever, and validating and updating the Lab-score.
  
  
  METHODS
  In this prospective observational study previously healthy children with fever, 1 month to 16 years of age, attending the EDs of a university hospital and a teaching hospital (Rotterdam, the Netherlands) between 2009 and 2012 were included. Standardized information on clinical signs and symptoms, CRP, PCT and urinalysis were collected prospectively. Logistic multivariable regression analysis was used to assess diagnostic performance. The original Lab-score included CRP, PCT and urinalysis and the total score ranged 0-9 points.
  
  
  RESULTS
  One thousand eighty-four children were included, median age was 1.6 years (interquartile range: 0.8-3.5), 170 children (16%) had SBI. CRP [receiver operating characteristic (ROC)-area 0.77 (95% confidence interval [CI]: 0.69-0.85)] and PCT [ROC-area 0.75 (95% CI: 0.67-0.83)] were both strong predictors of SBI. Duration of fever had no added diagnostic value to CRP and PCT. The Lab-score performed well [ROC area 0.79 (95% CI: 0.72-0.87)], but threshold values performed similar to often used cutoffs of single biomarkers. An updated Lab-score improved only moderately [ROC area 0.83 (95% CI: 0.76-0.90)]. PCT did not alter post-test probabilities for SBI substantially in patients with low (<20 mg/L) or elevated CRP (≥ 100 mg/L) levels (67% of population).
  
  
  CONCLUSIONS
  CRP and PCT were both strong predictors of SBI. The original and updated Lab-score performed well, but thresholds values lacked diagnostic value for ruling out SBI. Depending on clinical risk thresholds, diagnostic testing can be limited to CRP or PCT, rather than both, in many febrile children.
authors.affiliation: From the *Department of Pediatrics, Erasmus MC-Sophia Children's Hospital; †Department of Pediatrics, Maasstad Hospital, Rotterdam, The Netherlands; ‡Division of Pediatric Emergency, University Children's Hospital, Geneva, Switzerland; §Department of Clinical Chemistry, Maasstad Ziekenhuis; ¶Department of Medical Decision Making, Erasmus MC; and ‖Department of Clinical Chemistry, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands.
authors.forename: Ruud G
authors.initials: RG
authors.lastname: Nijman
authors.forename: Henriëtte A
authors.initials: HA
authors.lastname: Moll
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Smit
authors.forename: Alain
authors.initials: A
authors.lastname: Gervaix
authors.forename: Floor
authors.initials: F
authors.lastname: Weerkamp
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Vergouwe
authors.forename: Yolanda B
authors.initials: YB
authors.lastname: de Rijke
authors.forename: Rianne
authors.initials: R
authors.lastname: Oostenbrink
mesh_terms: D000293:Adolescent; D019540:Area Under Curve; D001424:Bacterial Infections / Q000097:blood / Q000175:diagnosis* / Q000652:urine; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002097:C-Reactive Protein / Q000032:analysis*; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital; D005260:Female; D005334:Fever / Q000382:microbiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood*; D012372:ROC Curve; D018570:Risk Assessment; D013997:Time Factors; D016482:Urinalysis
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide