Sexton Paul, Black Peter, Wu Lian, Sommerville Fay, Hamed Maye, Metcalf Patricia, Kolbe John
Department of Medicine, University of Auckland, Auckland, New Zealand.
J Asthma. 2013 Aug;50(6):606-12. doi: 10.3109/02770903.2013.793706. Epub 2013 May 13.
Airflow obstruction in asthma is usually reversible, but fixed obstruction develops in some individuals. Little is known about risk factors for development of fixed airflow obstruction in nonsmokers with asthma.
This case-comparison study recruited nonsmokers aged over 45 years with physician-diagnosed asthma from specialist outpatient clinics and primary care. Two age-matched groups were recruited on the basis of spirometry: anobstructed group (post-bronchodilator FEV(1) ≤ 70% predicted, FEV1/FVC ratio < lower limit of normal) and a control group with normal lung function. Subjects completed a questionnaire and interview, and underwent spirometry, venesection, exhaled nitric oxide (ENO) measurement, allergen skinprick testing, and formal lung function testing.
Thirty-four obstructed subjects and 40 controls participated in the study. Obstructed subjects exhibited greater evidence of systemic inflammation, abnormal glucose homeostasis, and central obesity than controls. Obstructed subjects reported longer duration of asthma, and childhood respiratory infection was commoner in that group. Metabolic syndrome prevalence was similar between groups, but several features of insulin resistance were associated with reduced FEV(1). Cough and sputum were common among controls.
Risk of fixed airflow obstruction may correlate with lifetime asthma duration. Individuals with coexisting asthma and fixed airflow obstruction have heightened systemic inflammation. A variety of chronic respiratory symptoms are common among "healthy" nonsmokers with asthma.
哮喘中的气流阻塞通常是可逆的，但在一些个体中会发展为固定性阻塞。对于非吸烟哮喘患者发生固定性气流阻塞的危险因素知之甚少。
这项病例对照研究从专科门诊和初级保健机构招募了年龄超过45岁、经医生诊断为哮喘的非吸烟者。根据肺功能测定结果招募了两个年龄匹配的组：阻塞组（支气管扩张剂后FEV(1)≤预测值的70%，FEV1/FVC比值<正常下限）和肺功能正常的对照组。受试者完成了一份问卷和访谈，并接受了肺功能测定、静脉穿刺、呼出一氧化氮（ENO）测量、过敏原皮肤点刺试验和正式的肺功能测试。
34名阻塞组受试者和40名对照组受试者参与了研究。与对照组相比，阻塞组受试者表现出更强的全身炎症、葡萄糖稳态异常和中心性肥胖的证据。阻塞组受试者报告的哮喘病程更长，该组儿童期呼吸道感染更为常见。两组间代谢综合征患病率相似，但胰岛素抵抗的几个特征与FEV(1)降低有关。咳嗽和咳痰在对照组中很常见。
固定性气流阻塞的风险可能与哮喘的终生病程相关。同时患有哮喘和固定性气流阻塞的个体全身炎症加剧。在“健康”的非吸烟哮喘患者中，各种慢性呼吸道症状很常见。
