Correlation between decrease of CRP and resolution of airway inflammatory response, improvement of health status, and clinical outcomes during severe acute exacerbation of chronic obstructive pulmonary disease.

Circulating C-reactive protein (CRP) plays an important role in mediating extra-pulmonary complications of chronic obstructive pulmonary disease (COPD). The aim of this study was to investigate the relationship between changes in high sensitivity (hs)-CRP levels and the resolution of airway inflammatory markers and clinical health status during the recovery period after an acute exacerbation of COPD (AECOPD). Consecutive patients hospitalized for AECOPD were recruited. Serum hs-CRP, airway inflammatory markers, and COPD Assessment Test (CAT) score were evaluated at admission prior to treatment and at days 4, 7, and 14. Adverse outcomes were recorded. The relationship between changes in airway inflammatory markers, CAT score, and hs-CRP during the recovery period was studied. A total of 135 patients were enrolled. Serum hs-CRP levels at admission of patients with adverse outcomes were marginally higher than those without an adverse outcome (7.6 [4.8, 16.7] vs. 6.6 [4.7, 9.3], p = 0.061). Compared with patients without cardiovascular complications, patients with cardiovascular complications had higher serum hs-CRP levels at admission (11.6 [6.7, 16.7] vs. 6.6 [4.4, 10.0], p = 0.001). Sputum neutrophils were positively correlated to hs-CRP at admission (r = 0.474, p < 0.001). A decreasing hs-CRP level was positively related to decreasing sputum neutrophils at day 4 and 7 (r = 0.455, p < 0.001; r = 0.504, p < 0.001, respectively). Significant correlations between decreasing hs-CRP and CAT at all time-points were noted. Hs-CRP may be useful in monitoring airway inflammation resolution and improvement of health status during AECOPD treatment.