Department of Respiratory Medicine, Division Heart & Lungs, University Medical Center Utrecht, Heidelberglaan 100, HP. F.02.333, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.
Respir Med. 2011 Jun;105(6):907-15. doi: 10.1016/j.rmed.2011.01.008. Epub 2011 Feb 5.
To review the currently available literature comparing the FEV1/FVC <LLN with a fixed value of FEV1/FVC < 0.70 in diagnosing airflow obstruction in subjects aged >40 years.
A structured MEDLINE, EMBASE and Cochrane search of English-language literature was conducted. Studies comparing prevalence rates according to the LLN and a fixed value were included. Attention was paid to the choice of the reference test or gold standard used.
Eighteen studies met the inclusion criteria. Sixteen studies compared the rates of subjects diagnosed with airflow obstruction by either definition of airflow obstruction without using a non-independent reference standard (level 4 studies). Using a fixed value of FEV1/FVC, an overall higher number of subjects were diagnosed with airflow obstruction that increased with age. Two studies included a follow-up phase comparing risks of either hospitalization or occurrence of respiratory symptoms and mortality (level 2b studies). Adjusted risks of hospitalization (HR 2.6) or mortality (HR 1.3) were significantly larger in subjects with an FEV1/FVC below 0.70 but above the LLN (in-between group) compared to subjects with normal lung function.
The prevalence of spirometry-based COPD is greater when using the fixed value of FEV1/FVC in comparison to using the LLN. Based on one longitudinal study the in-between group appears to have a higher risk of hospitalization and mortality; therefore it seems that using the LLN of FEV1/FVC underestimates COPD. In absence of a gold standard of COPD longitudinal research will be necessary to determine which criterion is better and more clinically relevant.
回顾目前比较第 1 秒用力呼气量（FEV1）/用力肺活量（FVC）<LLN 与 FEV1/FVC<0.70 这两种诊断标准在年龄>40 岁人群中诊断气流受限的文献。
对英文文献进行了结构化的 MEDLINE、EMBASE 和 Cochrane 检索。纳入了比较根据 LLN 和固定值进行诊断的患病率的研究。注意使用参考测试或金标准的选择。
18 项研究符合纳入标准。16 项研究比较了两种定义的气流受限的诊断率，其中不使用独立的参考标准（4 级研究）。使用 FEV1/FVC 的固定值，随着年龄的增长，被诊断为气流受限的人数总体上更高。两项研究包括了一个随访阶段，比较了住院或出现呼吸道症状和死亡率的风险（2b 级研究）。与肺功能正常的受试者相比，FEV1/FVC 低于 0.70 但高于 LLN（在两者之间）的受试者，其住院（HR 2.6）或死亡（HR 1.3）的风险显著更大。
与使用 LLN 相比，使用 FEV1/FVC 的固定值时，基于肺量计的 COPD 患病率更高。基于一项纵向研究，中间组的住院和死亡风险似乎更高；因此，使用 FEV1/FVC 的 LLN 似乎低估了 COPD。在没有 COPD 金标准的情况下，需要进行纵向研究以确定哪种标准更好，更具有临床相关性。
