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CRP and procalcitonin best for dx in febrile children

Clinical Question:
What is the diagnostic value of laboratory tests for the diagnosis of serious infections in febrile children?

Bottom Line:
C-reactive protein and procalcitonin are the most effective laboratory tests for ruling in or ruling out serious infections in febrile children. Both tests are better at ruling out than ruling in disease. A white blood cell count is not useful, and other markers of inflammation do not provide good sensitivity or specificity. (LOE = 2a)

Van den Bruel A, Thompson MJ, Haj-Hassan T, et al. Diagnostic value of laboratory tests in identifying serious infections in febrile children: systematic review. BMJ 2011;342:d3082.  [PMID:21653621]

Study Design:
Meta-analysis (other)


Outpatient (any)

To conduct this systematic review, the authors searched 4 databases, including DARE, to find studies that evaluated the diagnostic accuracy of tests in febrile outpatient children at least 30 days of age. They identified 14 studies, all of moderate quality or low quality. The prevalence of serious infection ranged from 4.5% to 29.3%. The tests best at ruling in serious infection were C-reactive protein, using a cut-off of 80 mg/L (positive likelihood ratio [LR+] = 8.4; 95% CI, 5.1 - 14.1), and procalcitonin greater than 2 ng/mL (LR+ [from 2 studies] = 3.6 and 13.7; 95% CIs, 7.4 - 25.3 and 1.4 - 8.9). Using a C-reactive protein cutoff of 20 mg/L (negative likelihood ratio [LR-] = 19 - .25) and a procalcitonin cutoff of .5 ng/mL (LR- = .08 - .25) is effective in ruling out serious infection. An elevated white blood cell count is not effective at ruling in or ruling out disease. Combinations of tests did not appreciably improve diagnostic accuracy.


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