C-reactive protein to distinguish pneumonia from acute decompensated heart failure

Background: Patients with acute decompensated heart failure (ADHF) are frequently treated with unnecessary antibiotics since they are confused with pneumonia patients. Aim: To study the efficacy of measuring C-reactive protein (CRP) levels on admission and CRP velocity in differentiating ADHF from pneumonia. Methods: A retrospective observational study of ADHF and pneumonia patients admitted to a tertiary hospital during 2 years. Patients who were already treated with antibiotics on admission were excluded. Efficacy of CRP as a diagnostic marker was evaluated by using receiver operator curves (ROC). Results: Overall, 72 ADHF and 50 pneumonia patients were included in the study. The mean CRP levels on admission were 13.5 ± 13.5 mg/L for the ADHF patients and 127 ± 84 mg/L for the pneumonia patients (p < 0.001). CRP increases of ≥0.56 mg/L/h were diagnostic of pneumonia. CRP levels on admission together with CRP increases had a sensitivity of 0.96 and a specificity of 0.972 (p < 0.001) as markers to distinguish pneumonia from ADHF. Conclusions: This study emphasizes the dynamic nature of biomarkers. Demonstrating the efficiency of repeated CRP measurements in an acute setting will provide clinicians with a valuable tool for establishing the correct diagnosis and refraining from unnecessary use of antibiotics.