Initial Inflammatory Profile in Community-acquired Pneumonia Depends on Time since Onset of Symptoms

Rationale: Assessment of the inflammatory response can help the decision-making process when diagnosing community-acquired pneumonia (CAP), but there is a lack of information about the influence of time since onset of symptoms.Objectives: We studied the impact of the number of days since onset of symptoms on inflammatory cytokines and biomarker concentrations at CAP diagnosis in hospitalized patients.Methods: We performed a secondary analysis in two prospective cohorts including 541 patients in the derivation cohort and 422 in the validation cohort. The time since onset of symptoms was self-reported, and patients were classified as early presenters (<3 d) and nonearly presenters. Biomarkers (C-reactive protein [CRP] and procalcitonin [PCT] in both cohorts) and cytokines in the derivation cohort (IL-1, - 6, -8, -10, and tumor necrosis factor-α) were measured within 24 hours of hospital admission.Measurements and Main Results: In early presenters, CRP was significantly lower, whereas PCT, IL-6, and IL-8 wer...