Fever duration enhanced biomarker sensitivity in diagnosing radiographically confirmed community-acquired pneumonia in children.

Aim: Our aim was to examine how fever duration affected the ability of biomarkers to diagnose community-acquired pneumonia (CAP).

Methods: This was a retrospective cohort study of children aged 2-18 years who attended the emergency department at Schneider Children's Medical Centre of Israel with CAP from June 2015 to May 2020. The children underwent biomarker measurements and chest radiographs and optimal biomarker thresholds were identified. Biomarker predictions of x-ray positive CAP were analysed, using receiver operating characteristic curves and area under the curve calculations.

Results: We screened 3346 children, 509 met the inclusion criteria and 363 of those had x-ray positive CAP. White blood counts of >15 000/mm³ and absolute neutrophil counts of >11 200/mm³ showed significant discriminatory power on day 2 of a fever. A neutrophil to lymphocyte ratio (NLR) of >4.5 displayed significant discriminatory power from days 2-5 and peaked on day 4. C-reactive protein of 6.23 mg/dL was discriminatory on day 4.

Conclusion: Fever duration affected how effectively biomarkers diagnosed x-ray positive CAP and all were unreliable on day 1. The NLR showed the most consistent reliability and may be suitable for clinical decision-making. Fever duration should be considered to optimise diagnostic accuracy.