Interpretation of biomarkers at emergency department depends on onset of symptoms in community-acquired pneumonia

Introduction: Biomarkers are useful in the decision-making process in community-acquired pneumonia (CAP). Although it is known that some factors may influence levels of biomarkers there is a lack of information regarding the impact of onset of CAP symptoms. Aims: We aimed to evaluate the kinetics of biomarkers at CAP diagnosis with regard the time of onset of symptoms in CAP. Methods: Prospective longitudinal study conducted in two teaching hospitals recruiting episodes of admitted CAP. Demographic data, prognostic scales, comorbidity, and outcomes were recorded. CRP, PCT and IL-1, IL-6, IL-8, IL-10, TNF-α were measured in the first 24 hours from admission. Results: We included 335 patients with median days from onset of CAP symptoms of 4 days. Patients with longer duration of symptoms (>4 days) were younger, with lower initial severity (PSI) (p 4 days of symptoms regardless if they have received prior antibiotic or not. In relation to 2 days from onset of symptoms, CRP was lower in those with symptoms shorter than 2 days (p Conclusions: Patients with > 4 days of CAP symptoms seem to show decreasing levels (PCT, IL-6, IL-8). On the other hand, during the first 2 days, CRP may still be in an increasing phase. Interpretation of biomarkers should be performed considering time from onset of CAP symptoms.