Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada
Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada.
Eur Respir J. 2023 Mar 23;61(3). doi: 10.1183/13993003.01194-2022. Print 2023 Mar.
Subjects without a previous history of asthma, presenting with unexplained respiratory symptoms and normal spirometry, may exhibit airway hyperresponsiveness (AHR) in association with underlying eosinophilic (type 2 (T2)) inflammation, consistent with undiagnosed asthma. However, the prevalence of undiagnosed asthma in these subjects is unknown.
In this observational study, inhaled corticosteroid-naïve adults without previously diagnosed lung disease reporting current respiratory symptoms and showing normal pre- and post-bronchodilator spirometry underwent fractional exhaled nitric oxide ( ) measurement, methacholine challenge testing and induced sputum analysis. AHR was defined as a provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (PC) <16 mg·mL and T2 inflammation was defined as sputum eosinophils >2% and/or >25 ppb.
Out of 132 subjects (mean±sd age 57.6±14.2 years, 52% female), 47 (36% (95% CI 28-44%)) showed AHR: 20/132 (15% (95% CI 9-21%)) with PC <4 mg·mL and 27/132 (21% (95% CI 14-28%)) with PC 4-15.9 mg·mL. Of 130 participants for whom sputum eosinophils, or both results were obtained, 45 (35% (95% CI 27-43%)) had T2 inflammation. 14 participants (11% (95% CI 6-16%)) had sputum eosinophils >2% and PC ≥16 mg·mL, suggesting eosinophilic bronchitis. The prevalence of T2 inflammation was significantly higher in subjects with PC <4 mg·mL (12/20 (60%)) than in those with PC 4-15.9 mg·mL (8/27 (30%)) or ≥16 mg·mL (25/85 (29%)) (p=0.01).
Asthma, underlying T2 airway inflammation and eosinophilic bronchitis may remain undiagnosed in a high proportion of symptomatic subjects in the community who have normal pre- and post-bronchodilator spirometry.
无哮喘既往史、表现为不明原因呼吸系统症状且肺功能正常的患者可能存在气道高反应性（AHR），同时伴有潜在的嗜酸性粒细胞（2 型（T2））炎症，这与未确诊的哮喘一致。然而，这些患者中未确诊哮喘的患病率尚不清楚。
在这项观察性研究中，吸入性皮质类固醇初治、无既往肺部疾病的报告当前呼吸系统症状且支气管扩张剂预后肺功能正常的成年人接受呼出气一氧化氮（ ）测量、乙酰甲胆碱挑战测试和诱导痰分析。气道高反应性定义为引起用力呼气量在 1 秒内下降 20%的乙酰甲胆碱激发浓度（PC）<16mg·mL，T2 炎症定义为痰中嗜酸性粒细胞>2%和/或 >25ppb。
在 132 名受试者中（平均年龄±标准差 57.6±14.2 岁，52%为女性），47 名（36%（95%CI 28-44%））表现出 AHR：20/132（15%（95%CI 9-21%））PC<4mg·mL，27/132（21%（95%CI 14-28%））PC 4-15.9mg·mL。在 130 名获得痰嗜酸性粒细胞、 或两者结果的参与者中，45 名（35%（95%CI 27-43%））存在 T2 炎症。14 名参与者（11%（95%CI 6-16%））痰嗜酸性粒细胞>2%且 PC≥16mg·mL，提示嗜酸粒细胞性支气管炎。PC<4mg·mL 的患者中 T2 炎症的患病率明显高于 PC 4-15.9mg·mL（12/20（60%））或≥16mg·mL（8/27（30%））或（25/85（29%））（p=0.01）。
在社区中有正常支气管扩张剂预后肺功能的症状性患者中，哮喘、潜在的 T2 气道炎症和嗜酸粒细胞性支气管炎可能仍未得到诊断。
