Roles of C-reactive protein and its composite index in predicting acute exacerbation of bronchiectasis

Abstract

Abstract Background Bronchiectasis is a heterogeneous chronic respiratory complication characterized by previous lower respiratory infection, airway inflammation and dilation. As the leading cause of frequent hospitalizations and mortality in patients with bronchiectasis, the exacerbation of bronchiectasis remains poorly understood. C-reactive protein (CRP) is one of the extensively studied inflammatory biomarkers related to systemic inflammation. Therefore, we aimed to investigate the relationship between the composite index of CRP and bronchiectasis, especially the potential role of CRP and its composite index in predicting acute exacerbation of bronchiectasis. Methods 223 patients with stable-stage bronchiectasis between January 1, 2009, and December 31, 2019 in Zhongshan Hospital of Fudan University were enrolled in the retrospectively study. The clinical information of times of acute exacerbations, the frequency of acute exacerbation, pulmonary function, chest computed tomography images, and laboratory findings of sputum examination, serum CRP, CAR (CRP/Albumin ratio), CPR (CRP/Prealbumin ratio) were collected. Based on the frequency of annual acute exacerbations, patients were divided into three groups: 0 times (group A), 1–2 times (group B), and 3 or more times (group C). Results There were significant differences in CRP, CAR, CPR, albumin, and prealbumin levels among the three groups, and no significant differences in age, gender, disease duration, involved pulmonary lobes, pulmonary function, and clinical manifestations were observed. The patients in group C had the highest levels of serum CRP (12.25 ± 8.34 mg/l), CAR (0.31 ± 0.25), and CPR (60.83 ± 52.68), and the lowest levels of albumin (41.07 ± 5.61 g/L) and prealbumin (0.21 ± 0.05 g/L). Significant positive correlations were observed between CRP, CAR, CPR, and the frequency of acute exacerbations (P < 0.05), respectively. Ordered logistic regression analysis further identified CRP (odds ratio, OR = 1.140), CAR (OR = 1.125), and CPR (OR = 1.032) as risk factors for frequent acute exacerbations (≥ 3/year). ROC analysis revealed that CRP, CAR, and CPR were effective indexes in predicting at least three times of acute exacerbation per year, whose AUC values are 0.469, 0.464, and 0.460, respectively. Moreover, CAR demonstrated the highest sensitivity (0.742) with an optimal cut-off value of 0.15, while CPR displayed the highest specificity (0.815) with a maximum cut-off value of 43.03. Conclusion The levels of serum CRP and its composite index including CAR and CPR were significantly positively correlated with the frequency of acute exacerbations in patients with bronchiectasis. These indicators also showed potential values in predicting over twice acute exacerbation per year, which may help identify patients at risk of experiencing frequent acute exacerbations annually and take timely intervention measures..