Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, NTNU, Norwegian University of Science and Technology, Trondheim, Norway.
Clinic of Thoracic and Occupational Medicine, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
PLoS One. 2021 May 27;16(5):e0252386. doi: 10.1371/journal.pone.0252386. eCollection 2021.
Previous studies of associations of forced expiratory lung volume in one second (FEV1) with peak oxygen uptake (VO2peak) in chronic obstructive pulmonary disease (COPD) have not taken sex, age and height related variance of dynamic lung volumes into account. Nor have such demographic spread of spirometric measures been considered in studies comparing VO2peak between COPD phenotypes characterized by degree of emphysema. We aimed to assess the association of FEV1Z-score with VO2peak in COPD (n = 186) and investigate whether this association differs between emphysema (E-COPD) and non-emphysema (NE-COPD) phenotypes. Corresponding assessments using standardized percent predicted FEV1 (ppFEV1) were performed for comparison. Additionally, phenotype related differences in VO2peak were compared using FEV1Z-score and ppFEV1 as alternative expressions of FEV1. E-COPD and NE-COPD were defined by transfer factor of the lung for carbon monoxide below and above lower limits of normal (LLN), respectively. The associations were assessed in linear regression models. One unit reduction in FEV1Z-score was associated with 1.9 (95% CI 1.4, 2.5) ml/kg/min lower VO2peak. In stratified analyses, corresponding estimates were 2.2 (95% CI 1.4, 2.9) and 1.2 (95% CI 0.2, 2.2) ml/kg/min lower VO2peak in E-COPD and NE-COPD, respectively. The association did not differ statistically by COPD phenotype (p-value for interaction = 0.153). Similar estimates were obtained in analyses using standardized ppFEV1. Compared to NE-COPD, VO2peak was 2.2 (95% CI 0.8, 3.6) and 2.1 (95% CI 0.8, 3.5) ml/kg/min lower in E-COPD when adjusted for FEV1Z-score and ppFEV1, respectively. In COPD, FEV1Z-score is positively associated with VO2peak. This association was stronger in E-COPD but did not differ statistically by phenotype. Both the association of FEV1 with VO2peak and the difference in VO2peak comparing COPD phenotypes seems independent of sex, age and height related variance in FEV1. Mechanisms leading to reduction in FEV1 may contribute to lower VO2peak in E-COPD.
先前关于一秒用力呼气容积（FEV1）与峰值摄氧量（VO2peak）在慢性阻塞性肺疾病（COPD）中的关联的研究，并未考虑到与性别、年龄和身高相关的动态肺容积差异。在比较由肺气肿程度定义的 COPD 表型之间的 VO2peak 时，也没有考虑到这种人群中肺量计测量值的扩展。我们旨在评估 COPD 患者的 FEV1Z 评分与 VO2peak 的相关性（n = 186），并探讨这种相关性是否在肺气肿（E-COPD）和非肺气肿（NE-COPD）表型之间存在差异。为了进行比较，使用标准化的预计 FEV1（ppFEV1）进行了相应的评估。此外，还使用 FEV1Z 评分和 ppFEV1 作为 FEV1 的替代表达，比较了表型相关的 VO2peak 差异。E-COPD 和 NE-COPD 分别通过肺一氧化碳转移因子低于和高于正常值下限（LLN）来定义。使用线性回归模型评估关联。FEV1Z 评分降低一个单位，与 VO2peak 降低 1.9（95%CI 1.4，2.5）ml/kg/min 相关。在分层分析中，E-COPD 和 NE-COPD 分别对应的估计值为 2.2（95%CI 1.4，2.9）和 1.2（95%CI 0.2，2.2）ml/kg/min。COPD 表型之间的相关性没有统计学差异（交互检验 p 值=0.153）。在使用标准化 ppFEV1 的分析中，得到了类似的估计值。与 NE-COPD 相比，在调整了 FEV1Z 评分和 ppFEV1 后，E-COPD 的 VO2peak 分别低 2.2（95%CI 0.8，3.6）和 2.1（95%CI 0.8，3.5）ml/kg/min。在 COPD 中，FEV1Z 评分与 VO2peak 呈正相关。在 E-COPD 中，这种相关性更强，但表型之间没有统计学差异。FEV1 与 VO2peak 的相关性以及比较 COPD 表型之间的 VO2peak 差异似乎独立于与性别、年龄和身高相关的 FEV1 方差。导致 FEV1 降低的机制可能导致 E-COPD 中 VO2peak 降低。
