Sears M R
Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
Clin Chest Med. 2000 Jun;21(2):315-29. doi: 10.1016/s0272-5231(05)70269-0.
Although asthma is classically defined as reversible airflow obstruction, and often remits in younger subjects with milder disease, the natural history of asthma is that various degrees of airflow obstruction may persist and, in the long-term, asthma may become moderately to fully irreversible. Severe, irreversible airflow obstruction may develop despite apparently appropriate therapy and in the absence of other risk factors, such as smoking and environmental insults. All studies of subjects with persisting asthma show increased decline in lung function compared with normal subjects. Persistent abnormal physiology is reflected both in reduced airflow rates and in increased airway responsiveness. The cellular and molecular mechanisms of airway remodeling are described elsewhere in this issue. Questions not yet clearly answered are the reasons for these persistent abnormalities in some asthmatics, and which subjects are most at risk. Factors that adversely impact the outcome as adults identified relatively consistently among many longitudinal studies of the natural history of asthma include: Female gender. Environmental tobacco smoke exposure in childhood. Personal tobacco smoking in adolescence and adulthood. Age of onset of symptoms. Severity of childhood asthma. Duration of asthma. Severity of lung function abnormality in childhood. Bronchodilator reversibility. Degree of airway hyperresponsiveness. Delay in initiating anti-inflammatory therapy. Remission among adult asthmatics is uncommon, but is associated with better initial lung function, young age, male gender, and lesser degrees of airway responsiveness. The role of atopy remains controversial. Conversely, risk factors for death from asthma include older age, smoking, atopy, impaired lung function, and moderate to high reversibility. Treatment can improve lung function, reduce airway responsiveness, and improve quality of life. The overall effect of treatment on the natural history of the disease is not yet clear, despite significant short-term improvements from effective anti-inflammatory therapy.
虽然哮喘传统上被定义为可逆性气流阻塞，且在病情较轻的年轻患者中通常会缓解，但哮喘的自然病程是，各种程度的气流阻塞可能会持续存在，从长远来看，哮喘可能会发展为中度至完全不可逆。尽管进行了看似适当的治疗且不存在其他风险因素（如吸烟和环境损害），仍可能出现严重的、不可逆的气流阻塞。所有关于持续性哮喘患者的研究均显示，与正常受试者相比，其肺功能下降加剧。持续性异常生理表现为气流速率降低和气道反应性增加。气道重塑的细胞和分子机制在本期其他地方已有描述。一些尚未明确解答的问题是，部分哮喘患者出现这些持续性异常的原因是什么，以及哪些患者风险最高。在许多关于哮喘自然病程的纵向研究中，相对一致地确定的对成年后预后产生不利影响的因素包括：女性性别。儿童期接触环境烟草烟雾。青少年期和成年期个人吸烟。症状发作年龄。儿童哮喘的严重程度。哮喘病程。儿童期肺功能异常的严重程度。支气管扩张剂可逆性。气道高反应性程度。开始抗炎治疗的延迟。成年哮喘患者缓解情况不常见，但与较好的初始肺功能、年轻、男性性别以及较低程度的气道反应性相关。特应性的作用仍存在争议。相反，哮喘死亡的风险因素包括年龄较大、吸烟、特应性、肺功能受损以及中度至高度可逆性。治疗可改善肺功能、降低气道反应性并提高生活质量。尽管有效的抗炎治疗在短期内有显著改善，但治疗对该疾病自然病程的总体影响尚不清楚。
