CIRP might determine the presences of IDSA/ATS major/minor criteria and predicted best

Background: Severity of community-acquired pneumonia (CAP) depends on microbial pathogenicity, load and virulence, and immune responses. The IDSA/ATS minor criteria for severe CAP are of unequal weight in predicting mortality. It is unclear whether the major/minor criteria might be strongly and positively associated with the immune responses. Methods: A prospective cohort study of 404 CAP patients was performed. Results: Severe CAP patients meeting the major criteria presented the highest plasma concentrations of cold-inducible RNA-binding protein (CIRP). The more the number of most predictive minor criteria strongly associated to mortality, i.e. PaO2/FiO2 ≤ 250 mm Hg, confusion, and uremia, present, the higher the CIRP. Interestingly, the patients with non-severe CAP meeting the most predictive minor criteria demonstrated unexpectedly higher CIRP compared with the patients with severe CAP not fulfilling the most predictive minor criteria. Procalcitonin (PCT), interleukin-6 (IL-6), C-reactive protein (CRP), sequential organ failure assessment (SOFA) and pneumonia severity index (PSI) scores, and mortality confirmed similar intriguing patterns. CIRP was strongly linked to these indices. The pattern of sensitivity, specificity, positive predictive value, and Youden’s index of CIRP ≥ 3.50 ng/mL for predicting mortality was the optimal. The area under the receiver operating characteristic curve of CIRP was the highest among the indices. Conclusions: The major/minor criteria were strongly and positively associated with CIRP, which might determine the presences of severity criteria. CIRP predicted severity and mortality best, suggesting an intriguing biomarker for pneumonia.