IRCCS San Matteo Hospital Foundation, University of Pavia, Italy.
Eur Respir J. 2009 Sep;34(3):568-73. doi: 10.1183/09031936.00172908.
Asthma guidelines from the Global Initiative for Asthma (GINA) and from the National Heart, Lung, and Blood Institute provide conflicting definitions of airflow obstruction, suggesting a fixed forced expiratory volume in 1 s (FEV(1))/forced vital capacity (FVC) cut-off point and the lower limit of normality (LLN), respectively. The LLN was recommended by the recent American Thoracic Society/European Respiratory Society guidelines on lung function testing. The problem in using fixed cut-off points is that they are set regardless of age and sex in an attempt to simplify diagnosis at the expense of misclassification. The sensitivity and specificity of fixed FEV(1)/FVC ratios of 0.70, 0.75 and 0.80 versus the LLN were evaluated in 815 subjects (aged 20-44 yrs) with a diagnosis of asthma within the framework of the European Community Respiratory Health Survey. In males, the 0.70 ratio showed 76.5% sensitivity and 100.0% specificity, the 0.75 ratio 100.0% sensitivity and 92.4% specificity, and the 0.80 ratio 100.0% sensitivity but 58.1% specificity. In females, the 0.70 ratio showed 57.3% sensitivity and 100.0% specificity, the 0.75 ratio 91.5% sensitivity and 95.9% specificity, and the 0.80 ratio 100.0% sensitivity but 72.9% specificity. The fixed cut-off points cause a lot of misidentification of airflow obstruction in young adults, with overestimation with the 0.80 ratio and underestimation with the 0.70 ratio. In conclusion, the GINA guidelines should change their criteria for defining airflow obstruction.
哮喘指南由全球哮喘倡议（GINA）和美国国家心肺血液研究所（National Heart, Lung, and Blood Institute）制定，对气流受限的定义相互矛盾，分别建议使用固定的 1 秒用力呼气量（FEV1）/用力肺活量（FVC）比值截断点和正常值下限（LLN）。LLN 是最近美国胸科学会/欧洲呼吸学会（American Thoracic Society/European Respiratory Society）肺功能测试指南推荐使用的。使用固定截断点的问题在于，为了简化诊断，而不是为了错误分类，他们不顾年龄和性别来设置截断点。在欧洲社区呼吸健康调查框架内，对 815 名（年龄 20-44 岁）诊断为哮喘的患者使用固定 FEV1/FVC 比值 0.70、0.75 和 0.80 与 LLN 进行比较，评估其敏感性和特异性。在男性中，0.70 比值的敏感性为 76.5%，特异性为 100.0%；0.75 比值的敏感性为 100.0%，特异性为 92.4%；0.80 比值的敏感性为 100.0%，但特异性为 58.1%。在女性中，0.70 比值的敏感性为 57.3%，特异性为 100.0%；0.75 比值的敏感性为 91.5%，特异性为 95.9%；0.80 比值的敏感性为 100.0%，但特异性为 72.9%。固定截断点导致年轻人中气流受限的大量错误识别，0.80 比值高估，0.70 比值低估。总之，GINA 指南应该改变其定义气流受限的标准。
