ObjectiveTo investigate the relationship between the red blood cell distribution width (RDW) and the severity of acute exacerbation of bronchiectasis in elderly patients.MethodsThe clinical data of 216 elderly patients with acute exacerbation of bronchiectasis admitted from January 2015 to October of 2018 were analyzed retrospectively. The severity of acute exacerbation of bronchiectasis in the elderly was evaluated by bronchiectasis severity index (BSI) score. Meanwhile, 50 elderly people receiving qualified medical examination were collected as a healthy control group in the same period. The distributions of BSI score, RDW, procalcitonin (PCT), neutrophil percentage (NEU%) and C-reactive protein (CRP) were described in the patients with different risk degree. The severity of acute exacerbation of bronchiectasis in the elderly was evaluated by BSI. The patients were divided into three groups by BSI score: a low risk group, a middle risk group, and a high risk group. The indexes were described including the distribution of stratified BSI score, RDW, PCT, NEU%, CRP at different risk levels. The correlation of each index was analyzed by Spearman correlation. The threshold value of RDW was calculated by general linear regression, and the influencing factors of BSI score were analyzed by multivariate linear regression analysis.ResultsThe higher the risk stratification, the higher the BSI score, RDW, PCT, NEU% and CRP were. RDW was positively correlated with PCT, NEU% and CRP (r values were 0.425, 0.311, 0.177, respectively, P<0.05). BSI score was positively correlated with RDW, PCT, NEU%, and CRP (r values were 0.425, 0.394, 0.650, 0.578, respectively, P<0.05). RDW was positively correlated with PSI score (r=0.425, P<0.05). The thresholds of RDW were 11.45% and 14.03%. Multiple linear regression showed that RDW, PCT, NEU% and CRP were all influential factors of BSI score and explained 52.3% of the total mutation rate.ConclusionRDW is related to the severity of acute exacerbation of bronchiectasis in the elderly, and can predict the severity of acute exacerbation of bronchiectasis in the elderly.