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Diagnostic value of laboratory tests in identifying serious infections in febrile children: systematic review

BMJ 2011; 342 doi: (Published 08 June 2011) Cite this as: BMJ 2011;342:d3082

Marker interpretation in febrile children

Van den Bruel et al presented a high quality systematic review on the
diagnostic value of laboratory tests in febrile children (1).

We published nearly at the same time a prospective cohort study
comparing the diagnostic properties of procalcitonin (PCT), C-reactive
protein (CRP), total white blood cells count, absolute neutrophil count
and clinical evaluation to detect serious bacterial infection (SBI) in
children with fever without source (2). Our results were very similar (2)
. Also, we both concluded that a surrogate marker should always be
interpreted depending on the value obtained in each patient: the higher
the result, the higher the probability of having an SBI as illustrated by
multilevel likelihood ratios. For example, in our study, a PCT
concentration >2 ng/ml or a CRP concentration >80 mg/l raised the
SBI probability from 3% to 20% if urine analysis is normal, and a PCT
>10 ng/ml was diagnostic of SBI in these children. Conversely, a CRP
<10 mg/l in that situation lowers SBI probability to less than 1%. This
has also been reported by other authors (3-5).

Thus, these markers can play an important role in the decision making
process when multilevel likelihood ratios are used.


1. Van den Bruel A, Thompson MJ, Haj-Hassan T, Stevens R, Moll H,
Lakhanpaul M, et al. Diagnostic value of laboratory tests in identifying
serious infections in febrile children: systematic review. Bmj;342:d3082.

2. Manzano S, Bailey B, Gervaix A, Cousineau J, Delvin E, Girodias
JB. Markers for bacterial infection in children with fever without source.
Arch Dis Child;96(5):440-6.

3. Bilavsky E, Yarden-Bilavsky H, Ashkenazi S, Amir J. C-reactive
protein as a marker of serious bacterial infections in hospitalized
febrile infants. Acta Paediatr 2009;98(11):1776-80.

4. Galetto-Lacour A, Zamora SA, Gervaix A. Bedside procalcitonin and
C-reactive protein tests in children with fever without localizing signs
of infection seen in a referral center. Pediatrics 2003;112(5):1054-60.

5. Pulliam PN, Attia MW, Cronan KM. C-reactive protein in febrile
children 1 to 36 months of age with clinically undetectable serious
bacterial infection. Pediatrics 2001;108(6):1275-9.

Competing interests: No competing interests

02 August 2011
Sergio Manzano
paediatric emergency physician
Benoit Bailey, paediatric emergency physician
University Hospital of Geneva (Switzerland) and Sainte Justine Hospital, Montreal (Canada)