C-reactive protein diagnostic value for bacterial infections in the paediatric emergency department setting

Aim: C-reactive protein (CRP) is commonly used to assess the probability of bacterial infection and the need for empiric antibiotic treatment. We assessed the relationship between CRP levels and bacterial infection in the paediatric emergency room (PER) setting.

Methods: A retrospective cohort study. Relative risks (RRs) were calculated for the relation between CRP levels and various demographic, clinical and diagnosis parameters. Additionally, the sensitivity and specificity of different CRP levels (2, 5, 7 and 10 mg/dL) for bacterial infection diagnosis was calculated.

Results: Overall, 13 092 cases were recorded. Fever, leucocytosis, hospitalisation and bacterial infection diagnosis were associated with elevated CRP levels, while lower CRP levels were associated with young age. Gender, ethnicity, hypoxemia and neutrophilia were not associated with CRP levels. The sensitivity of CRP ≥2 mg/dl for bacterial disease was 65%-70%, declining to <50% in CRP ≥5 mg/dL. The specificity of CRP ≥2 mg/dL for bacterial disease was ~60%, increasing to >80% in CRP ≥5 mg/dL.

Conclusions: CRP levels of ≥5 mg/dl high specificity for bacterial disease, allow for its use as an indicator to start empiric antibiotic treatment, while the low sensitivity of various CRP levels probably excludes the possibility of withholding empiric antibiotic treatment, based only on CRP level.