Inflammatory biomarkers in predicting ICU admission of severe community-acquired pneumonia (CAP)

Introduction: Increased inflammation is related with severity and outcome in CAP, but the role of inflammatory biomarkers in deciding ICU admission is unknown. We assessed the relationship between inflammatory response, prediction for ICU admission, delayed ICU admission, and outcome in patients with CAP. Methods: We prospectively assessed 627 ward and 58 ICU patients (36 direct and 22 delayed ICU admission), determined serum levels of C-reactive protein (CRP), Procalcitonin, TNF-alpha, IL-1, IL-6, IL-8 and IL-10 at admission, and assessed the prediction for ICU admission of biomarkers and the IDSA/ATS guidelines criteria for severe CAP. Results: Procalcitonin (p=0.001), CRP (p=0.005), TNF-alpha (p=0.042) and IL-6 (p=0.003) levels were higher in ICU patients, but the IDSA/ATS guidelines minor criteria predicted better ICU admission (OR 12.0, 95% CI 5.1-28.2, p<0.001). No patient with ≥3 minor criteria and Procalcitonin levels < 0.35 ng/mL needed ICU admission, compared with 14 (23%) with levels above this optimal cutoff (p=0.032). In initially-ward patients, Procalcitonin (p=0.012) and CRP (p=0.039) predicted subsequent ICU transfer, adjusted for age, co-morbidities and PSI risk class. Despite initially in wards, 14 (64%) patients with delayed ICU admission had criteria for severe CAP at admission, compared with 73 (12%) ward patients (p<0.001). Conclusion: Although the IDSA/ATS guidelines minor criteria identified patients needing ICU admission better than biomarkers, low levels of Procalcitonin discarded ICU admission in those with minor criteria. Correctly applying these guidelines would reduce delayed ICU admission. Funded: CibeRes (CB06/06/0028), 2009 SGR 911, FIS 08/0727, IDIBAPS.