Center for Access & Delivery Research & Evaluation (CADRE), Iowa City VA Health Care System, Iowa City, IA.
Department of Internal Medicine, Division of Pulmonary, Critical Care and Occupation Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA.
Chest. 2021 Jul;160(1):94-103. doi: 10.1016/j.chest.2021.01.067. Epub 2021 Feb 1.
Mild expiratory flow limitation may not be recognized using traditional spirometric criteria based on the ratio of FEV/FVC.
Does slow vital capacity (SVC) instead of FVC increase the sensitivity of spirometry to identify patients with early or mild obstructive lung disease?
We included 854 current and former smokers from the Subpopulations and Intermediate Outcome Measures in COPD Study cohort with a postbronchodilator FEV/FVC ≥ 0.7 and FEV % predicted of ≥ 80% at enrollment. We compared baseline characteristics, chest CT scan features, exacerbations, and progression to COPD (postbronchodilator FEV/FVC, < 0.7) during the follow-up period between 734 participants with postbronchodilator FEV/SVC of ≥ 0.7 and 120 with postbronchodilator FEV/SVC < 0.7 at the enrollment. We performed multivariate linear and logistic regression models and negative binomial and interval-censored proportion hazards regression models adjusted for demographics and smoking exposure to examine the association of FEV/SVC < 0.7 with those characteristics and outcomes.
Participants with FEV/SVC < 0.7 were older and had lower FEV and more emphysema than those with FEV/SVC ≥ 0.7. In adjusted analysis, individuals with postbronchodilator FEV/SVC < 0.7 showed a greater percentage of emphysema by 0.45% (95% CI, 0.09%-0.82%), percentage of gas trapping by 2.52% (95% CI, 0.59%-4.44%), and percentage of functional small airways disease based on parametric response mapping by 2.78% (95% CI, 0.72%-4.83%) at baseline than those with FEV/SVC ≥ 0.7. During a median follow-up time of 1,500 days, an FEV/SVC < 0.7 was not associated with total exacerbations (incident rate ratio [IRR], 1.61; 95% CI, 0.97-2.64), but was associated with severe exacerbations (IRR, 2.60; 95% CI, 1.04-4.89). An FEV/SVC < 0.7 was associated with progression to COPD during a 3-year follow-up even after adjustment for demographics and smoking exposure (hazard ratio, 3.93; 95% CI, 2.71-5.72). We found similar results when we examined the association of prebronchodilator FEV/SVC < 0.7 or FEV/SVC less than the lower limit of normal with chest CT scan features and progression to COPD.
Low FEV to SVC in current and former smokers with normal spirometry results can identify individuals with CT scan features of COPD who are at risk for severe exacerbations and is associated with progression to COPD in the future.
ClinicalTrials.gov; No.: NCT01969344T4; URL: www.clinicaltrials.gov.
根据 FEV/FVC 比值的传统肺量计标准，轻度呼气流量受限可能无法被识别。
肺活量（VC）降低而不是 FVC 降低是否会提高肺量计识别早期或轻度阻塞性肺疾病患者的敏感性？
我们纳入了 COPD 亚人群和中间结局研究队列中的 854 名当前和曾经的吸烟者，这些吸烟者在支气管扩张剂后 FEV/FVC≥0.7，并且在入组时 FEV%预测值≥80%。我们比较了 734 名支气管扩张剂后 FEV/SVC≥0.7 和 120 名支气管扩张剂后 FEV/SVC<0.7 的参与者在随访期间的基线特征、胸部 CT 扫描特征、加重情况以及进展为 COPD（支气管扩张剂后 FEV/FVC，<0.7）的情况。我们进行了多元线性和逻辑回归模型以及负二项式和区间 censored 比例风险回归模型的分析，这些模型调整了人口统计学和吸烟暴露因素，以检查 FEV/SVC<0.7 与这些特征和结局的关联。
与 FEV/SVC≥0.7 的参与者相比，FEV/SVC<0.7 的参与者年龄更大，FEV 更低，肺气肿更多。在调整分析中，与 FEV/SVC≥0.7 的参与者相比，支气管扩张剂后 FEV/SVC<0.7 的参与者的肺气肿百分比增加了 0.45%（95%CI，0.09%-0.82%），气体滞留百分比增加了 2.52%（95%CI，0.59%-4.44%），基于参数响应映射的功能性小气道疾病百分比增加了 2.78%（95%CI，0.72%-4.83%）。在中位随访时间为 1500 天期间，FEV/SVC<0.7 与总加重次数（发生率比[IRR]，1.61；95%CI，0.97-2.64）无关，但与严重加重次数（IRR，2.60；95%CI，1.04-4.89）有关。即使在调整了人口统计学和吸烟暴露因素后，FEV/SVC<0.7 仍与 COPD 的 3 年随访期间的进展相关（风险比，3.93；95%CI，2.71-5.72）。当我们检查支气管扩张剂前 FEV/SVC<0.7 或 FEV/SVC 低于正常下限与胸部 CT 扫描特征和进展为 COPD 的关系时，我们发现了类似的结果。
在正常肺量计结果的当前和曾经吸烟者中，低 FEV 与 SVC 的比值可以识别出 CT 扫描具有 COPD 特征的个体，这些个体有发生严重加重的风险，并与未来进展为 COPD 相关。
ClinicalTrials.gov；编号：NCT01969344T4；网址：www.clinicaltrials.gov。
