Gibson P G, Simpson J L
Department of Respiratory and Sleep Medicine, John Hunter Hospital, Hunter Mail Centre, Newcastle, NSW 2310, Australia.
Thorax. 2009 Aug;64(8):728-35. doi: 10.1136/thx.2008.108027.
There is a need to re-evaluate the concept of asthma and chronic obstructive pulmonary disease (COPD) as separate conditions, and to consider situations when they may coexist, or when one condition may evolve into the other. Epidemiological studies show that in older people with obstructive airway disease, as many as half or more may have overlapping diagnoses of asthma and COPD (overlap syndrome). These people are typically excluded from current therapy trials, which limit the generalisability of these trials, and this presents a problem for evidence-based guidelines for obstructive airway diseases. Studying overlap syndrome may shed light on the mechanisms of COPD development. Overlap syndrome is recognised by the coexistence of increased variability of airflow in a patient with incompletely reversible airway obstruction. Patients typically have inflammatory features that resemble COPD, with increased airway neutrophilia, as well as features of airway wall remodelling. Overlap syndrome can develop when there is accelerated decline in lung function, or incomplete lung growth, or both. The risk factors for these events are shared, such that increasing age, bronchial hyper-responsiveness, tobacco smoke exposure, asthma and lower respiratory infections/exacerbations are significant risk factors for both incomplete lung growth and accelerated loss of lung function. Studying these events may offer new insights into the mechanisms and treatment of obstructive airway diseases.
有必要重新评估将哮喘和慢性阻塞性肺疾病（COPD）视为不同病症的概念，并考虑它们可能共存的情况，或者一种病症可能演变为另一种病症的情况。流行病学研究表明，在患有阻塞性气道疾病的老年人中，多达一半或更多的人可能同时被诊断为哮喘和COPD（重叠综合征）。这些人通常被排除在当前的治疗试验之外，这限制了这些试验的普遍性，并且这给阻塞性气道疾病的循证指南带来了问题。研究重叠综合征可能有助于揭示COPD发展的机制。重叠综合征的特征是在气道阻塞不完全可逆的患者中气流变异性增加。患者通常具有类似于COPD的炎症特征，气道中性粒细胞增多，以及气道壁重塑的特征。当肺功能加速下降、肺生长不完全或两者兼有时，重叠综合征就会发生。这些事件的风险因素是相同的，因此年龄增长、支气管高反应性、接触烟草烟雾、哮喘和下呼吸道感染/加重是肺生长不完全和肺功能加速丧失的重要风险因素。研究这些事件可能会为阻塞性气道疾病的机制和治疗提供新的见解。
