Value of biomarkers in the diagnosis of community-acquired pneumonia with concomitant chronic heart failure: a prospective observation study.

Background The diagnosis of community-acquired pneumonia (CAP) in patients with chronic heart failure (CHF) is associated with objective difficulties due to similar clinical presentation. We aimed to evaluate the utility of serum biomarkers - С-reactive protein (CRP), procalcitonin (PCT), tumour necrosis factor α (TNFα), interleukin-6 (IL-6) and brain natriuretic peptide (BNP) in diagnosis of CAP in the presence of СHF.Methods Prospective observational study included patients with previously diagnosed CHF and suspected non-severe CAP. Participants underwent routine procedures and chest multispiral computed tomography (MSCT); serum levels of biomarkers (CRP, PCT, TNFα, IL-6) and BNP were measured. All patients were divided into group 1 with confirmed CAP and group 2 with excluded CAP according to MSCT findings. Standard statistical tools were applied, p-value <0.05 in two-tailed tests was considered statistically significant. The value of biomarkers was determined using logistic regression, their discriminatory efficacy was assessed by analyzing Receiver Operation Characteristic (ROC) curves.Results Altogether 35 with CAP (median age 78 (64-82) years, female 24/35 (68.6%)) and 35 - without CAP (median age 77 (71-82) years, female 22/35 (62.9%)) were enrolled. There were no differences between groups in baseline characteristics, with the exception of body temperature. We found significantly higher levels of CRP 50.0 (35.5-98.5) mg/L, PCT 0.10 (0.05-0.54) ng/mL and IL-6 46.1 (21.4-150.3) pg/mL in group 1 as compared to group 2 - 15.0 (9.5-25.0) mg/L, 0.05 (0.05-0.05) ng/mL and 13,6 (9,5; 25,0) pg/mL, respectively. AUC (95% CI) was the highest for CRP – 0.91 (0.83-0.98), followed by PCT – 0.81 (0.72-0.90) and IL-6 – 0.81 (0.71-0.91). CRP value of 28.5 mg/L had optimal sensitivity and specificity ratio (85.7/91.4%).Conclusion The measurement of serum CRP, PCT, IL-6 levels can be useful for diagnostics of CAP in patients with concomitant CHF. CRP had the optimal diagnostic utility in this population.