Diagnostic properties of C-reactive protein for detecting pneumonia in children.

Background: The diagnostic value of C-reactive protein (CRP) level for pneumonia in children is unknown. As a first step in the assessment of the value of CRP, a diagnostic study was performed in children at an emergency department (ED).

Methods: In this cross-sectional study, data were retrospectively collected from children presenting with suspected pneumonia at the ED of Antonius Hospital Nieuwegein in The Netherlands between January 2007 and January 2012. Diagnostic outcome was pneumonia yes/no according to independent radiologist. (Un)adjusted association between CRP level and pneumonia and diagnostic value of CRP were calculated.

Results: Of 687 presenting children, 286 underwent both CRP measurement and chest radiography. 148 had pneumonia (52%). The proportion of pneumonia increased with CRP level. Negative predictive values declined, but positive predictive values increased with higher CRP thresholds. Univariable odds ratio for the association between CRP level and pneumonia was 1.2 (95% CI 1.11-1.21) per 10 mg/L increase. After adjustment for baseline characteristics CRP level remained associated with pneumonia.

Conclusions: CRP level has independent diagnostic value for pneumonia in children presenting at the ED with suspected pneumonia, but low levels do not exclude pneumonia in this setting. These results prompt evaluation of CRP in primary care children with LRTI.