BACKGROUND Small-airways instability resulting in premature airway closure has been recognized as a risk for asthma severity and poor control. Although spirometry has limited sensitivity for detecting small-airways dysfunction, a focus on the air-trapping component of obstruction might identify a risk factor for asthma instability. OBJECTIVE We sought to use spirometric measurements to identify patterns of airway obstruction in children and define obstruction phenotypes that relate to asthma instability. METHODS Prebronchodilation and postbronchodilation spirometric data were obtained from 560 children in the Asthma Phenotypes in the Inner City study. An air-trapping obstruction phenotype (A Trpg) was defined as a forced vital capacity (FVC) z score of less than -1.64 or an increase in FVC of 10% of predicted value or greater with bronchodilation. The airflow limitation phenotype (A Limit) had an FEV1/FVC z score of less than -1.64 but not A Trpg. The no airflow limitation or air-trapping criteria (None) phenotype had neither A Trpg nor A Limit. The 3 obstruction phenotypes were assessed as predictors of number of exacerbations, asthma severity, and airway lability. RESULTS Patients with the A Trpg phenotype (14% of the cohort) had more exacerbations during the 12-month study compared with those with the A Limit (P < .03) and None (P < .001) phenotypes. Patients with the A Trpg phenotype also had the highest Composite Asthma Severity Index score, the highest asthma treatment step, the greatest variability in FEV1 over time, and the greatest sensitivity to methacholine challenge. CONCLUSIONS A Trpg and A Limit patterns of obstruction, as defined by using routine spirometric measurements, can identify obstruction phenotypes that are indicators of risk for asthma severity and instability.

中文翻译：

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阻塞表型作为儿童哮喘严重程度和不稳定性的预测因子。


背景技术导致气道过早闭合的小气道不稳定已被认为是哮喘严重程度和控制不良的风险。尽管肺活量测定法检测小气道功能障碍的灵敏度有限，但关注阻塞的空气滞留成分可能会确定哮喘不稳定的危险因素。目的 我们试图使用肺活量测量来识别儿童气道阻塞的模式，并定义与哮喘不稳定相关的阻塞表型。方法 在内城研究中的哮喘表型研究中，获得了 560 名儿童的支气管扩张前和支气管扩张后肺量测定数据。空气滞留阻塞表型 (A Trpg) 定义为用力肺活量 (FVC) z 评分低于 -1.64 或 FVC 在支气管扩张时增加预测值的 10% 或更高。气流受限表型 (A Limit) 的 FEV1/FVC z 分数低于 -1.64，但 A Trpg 则不然。无气流限制或空气滞留标准（无）表型既没有 A Trpg 也没有 A Limit。评估 3 种阻塞表型作为恶化次数、哮喘严重程度和气道不稳定性的预测因子。结果 与具有 A Limit (P < .03) 和 None (P < .001) 表型的患者相比，具有 A Trpg 表型的患者（队列中的 14%）在 12 个月的研究中出现更多的病情加重。具有 A Trpg 表型的患者还具有最高的综合哮喘严重程度指数评分、最高的哮喘治疗步骤、FEV1 随时间变化的最大变异性以及对乙酰胆碱激发的最大敏感性。 结论 根据使用常规肺活量测量定义的 A Trpg 和 A Limit 阻塞模式，可以识别阻塞表型，这些表型是哮喘严重程度和不稳定风险的指标。