Department of Paediatric Respiratory Medicine, Imperial School of Medicine at National Heart and Lung Institute, London, United Kingdom.
Proc Am Thorac Soc. 2009 Dec;6(8):712-9. doi: 10.1513/pats.200906-046DP.
The goal of asthma phenotyping is to understand disease mechanisms or optimize management. Phenotypes show age-related variation. The phenotypes of wheezing in the first year of life are little studied; many remit in the second year of life, and the children who remit do not have later-onset wheeze, as far as is known. Preschool wheeze is optimally phenotyped by symptom pattern, defined as either episodic viral or multiple-trigger wheeze, which allows rational treatment planning. In school age and adult life, most patients with mild asthma can be managed adequately without phenotyping, but severe asthma clearly falls into several phenotypic groups. Children with severe asthma have no gender bias and are highly atopic with relatively well-preserved lung function, in contrast to the female-preponderant, non-atopic bias seen in adults. Phenotyping has been mainly by proximal luminal cellularity. However, this does not take account of any variation of cellularity over time, distal airway changes, or the relative contribution of mucosal and luminal inflammatory changes. There may be a separate exacerbating phenotype, characterized by airway eosinophilia. Particular adult phenotypes include late-onset asthma and a phenotype characterized by progressive loss of lung function, but critical review suggests that these phenotypes may also have childhood roots. Longitudinal data are needed to determine the stability of phenotypes and their prognoses. Retrospective recall of childhood events is of limited value. In conclusion, a full understanding the multifaceted phenotypes of asthma requires a thorough knowledge of early life events and their consequences over many decades.
哮喘表型的目标是了解疾病机制或优化管理。表型表现出与年龄相关的变化。生命第一年喘息的表型研究甚少；许多在第二年缓解，据所知，这些缓解的儿童没有以后出现喘息。通过症状模式（定义为发作性病毒或多种触发喘息）对学龄前喘息进行最佳表型分析，这可以合理地进行治疗计划。在学龄期和成年期，大多数轻度哮喘患者无需表型分析即可得到充分管理，但严重哮喘显然属于几个表型组。患有严重哮喘的儿童没有性别偏见，且高度过敏，肺功能相对保存良好，与成年期女性为主、非过敏的偏见形成鲜明对比。表型主要通过近端腔细胞性来确定。然而，这并没有考虑到细胞数量随时间的任何变化、远端气道变化，或黏膜和腔炎症变化的相对贡献。可能存在一个单独的加重表型，其特征为气道嗜酸性粒细胞增多。特定的成人表型包括迟发性哮喘和以肺功能进行性丧失为特征的表型，但关键回顾表明这些表型也可能有儿童时期的根源。需要纵向数据来确定表型的稳定性及其预后。对儿童时期事件的回顾性回忆价值有限。总之，要充分了解哮喘的多方面表型，需要深入了解生命早期事件及其在几十年中的后果。
