Introduction. There is a controversy regarding the relationship between blood eosinophil count and COPD exacerbation. We aimed to determine whether peripheral eosinophils upon COPD diagnosis could affect the frequency and severity of annual acute exacerbation of COPD (AECOPD). Methods. This prospective study was conducted on 973 newly diagnosed COPD patients who were under 1-year follow-up in a pulmonology center in Iran. The Cox proportional model, polynomial regression, and receiver operator characteristic curves were conducted to evaluate the impact of the eosinophil levels on AECOPD. A linear regression model was conducted to evaluate the continuous association of eosinophilic count with AECOPDs. Results. Patients with eosinophil >200 cells/microliter were higher pack-year smokers with more pulmonary hypertension prevalence compared to COPD patients with <200 cells/microliter. There was a positive correlation between the eosinophilic count and the frequency of AECOPDs. Eosinophil >900 cells/microliter and eosinophil >600 cells/microliter had a sensitivity of 71.1% and 64.3%, respectively, in predicting the occurrence of more than one AECOPD. Eosinophilic count cutoff of 800 cells/microliter had the highest Youden index with sensitivity and specificity of 80.2% and 76.6%, respectively, for incident AECOPD in newly diagnosed patients. Using a linear model, increasing 180 cells/microliter in serum eosinophils was associated with further exacerbation. Evaluating gender, BMI, smoking pack-year, FEV1/FVC, CAT score, GOLD score, pulmonary hypertension, annual influenza, pneumococcal vaccinations, leukocytosis, and blood eosinophils, only blood eosinophils (hazard ratio (HR) = 1.44; 95% confidence interval = 1.33–2.15; value = 0.03) and GOLD score (HR = 1.19; 95% CI = 1.30–1.52; value = 0.03) were found as independent risk factors of AECOPD >3 episodes/year. Requirement for ICU admission, invasive ventilation, and mortality rate due to AECOPDs was similar between eosinophilic and noneosinophilic groups. Conclusion. Eosinophilia upon COPD diagnosis is a factor of recurrent AECOPDs. To reduce the risk of AECOPDs and the burden of disease, clinicians may consider inhaler corticosteroids and domiciliary oxygen with a lower threshold for eosinophilic-COPD patients regardless of their clinical status.

中文翻译：

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诊断后血液嗜酸性粒细胞计数与慢性阻塞性肺疾病每年恶化的频率和严重程度的关联：一项前瞻性纵向分析

介绍。关于血液嗜酸性粒细胞计数与 COPD 恶化之间的关系存在争议。我们的目的是确定 COPD 诊断后的外周嗜酸性粒细胞是否会影响 COPD 年度急性加重 (AECOPD) 的频率和严重程度。方法。这项前瞻性研究是对 973 名新诊断的 COPD 患者进行的，这些患者在伊朗的一个肺科中心接受了 1 年的随访。Cox 比例模型、多项式回归和接受者操作员特征曲线用于评估嗜酸性粒细胞水平对 AECOPD 的影响。进行线性回归模型以评估嗜酸性粒细胞计数与 AECOPD 的连续关联。结果. 与 <200 个细胞/微升的 COPD 患者相比，嗜酸性粒细胞 >200 个细胞/微升的患者吸烟年数更高，肺动脉高压患病率更高。嗜酸性粒细胞计数与 AECOPD 的频率呈正相关。嗜酸性粒细胞 >900 个细胞/微升和嗜酸性粒细胞 >600 个细胞/微升在预测一种以上 AECOPD 的发生方面的敏感性分别为 71.1% 和 64.3%。800 个细胞/微升的嗜酸性粒细胞计数截断值具有最高的约登指数，对于新诊断患者的 AECOPD 事件的敏感性和特异性分别为 80.2% 和 76.6%。使用线性模型，血清嗜酸性粒细胞增加 180 个细胞/微升与进一步恶化相关。评估性别、BMI、吸烟包年、FEV1/FVC、CAT 评分、GOLD 评分、值 = 0.03）和 GOLD 评分（HR = 1.19；95% CI = 1.30–1.52；值 = 0.03）被认为是 AECOPD >3 次/年的独立危险因素。ICU 入住要求、有创通气和 AECOPD 导致的死亡率在嗜酸性粒细胞和非嗜酸性粒细胞组之间相似。结论。COPD 诊断后的嗜酸性粒细胞增多是 AECOPD 复发的一个因素。为了降低 AECOPD 的风险和疾病负担，无论临床状态如何，临床医生都可以考虑对嗜酸性粒细胞性 COPD 患者使用吸入性皮质类固醇和具有较低阈值的家庭吸氧。