Diagnostic and prognostic value of inflammatory parameters including neopterin in pneumonia, COPD and acute exacerbations of COPD
Introduction: Acute exacerbations and community acquired pneumonia (CAP) are severe complications in patients with chronic obstructive pulmonary disease (COPD), increasing hospitalization rates, morbidity and mortality. In this study inflammatory parameters including C-reactive protein (CRP), procalcitonin (PCT) and serum neopterin (NPT) were determined to evaluate their prognostic and diagnostic value, especially to differentiate between patients with CAP+COPD and with acute exacerbations of COPD (AECOPD) without pneumonia.
Material & Methods: 131 patients (CAP: n = 65, mean age 65y, CAP+ COPD: n = 29, mean age 71y, AECOPD: n = 37, mean age 69y; overall 51 female and 80 male patients) were included in this study. CRP, PCT and blood counts were determined by routine automated tests, NPT concentrations by ELISA. The ratios of CRP to PCT and CRP to NPT levels were calculated and were used to identify cutoffs for discrimination between AECOPD and CAP (+/- COPD).
Results: CRP and PCT levels were higher in patients with CAP (+/- COPD) compared to AECOPD patients (AECOPD vs. CAP p < 0.001; AECOPD vs. CAP+COPD p < 0.001). NPT levels were higher in patients with CAP compared to AECOPD patients (median 24.0 vs. 16.5 nM, p = 0.027). CRP/NPT ratio was lower in AECOPD compared to CAP (+/- COPD) patients (AECOPD vs. CAP p < 0.001; AECOPD vs. CAP+COPD, p < 0.001).
Positive correlations were found between duration of hospitalization and CRP, PCT and NPT concentrations. Patients who died within 30 days had higher NPT levels compared to survivors.
Calculation of the CRP/NPT-ratio suited well to discriminate between AECOPD and CAP, a CRP/NPT cutoff of 0.275 provided a sensitivity of 69% and a specificity of 83% to discriminate between the two diagnoses.
Discussion: Our data confirm different inflammatory patterns in patients with AECOPD, CAP+COPD and CAP only. Our findings for the first time support the hypothesis that a fast discrimination between AECOPD and CAP+COPD is practicable by determining CRP and NPT levels. NPT levels may provide further prognostic information e.g. about duration of hospitalization as well as short term prognosis of patients.