Moon Seong Mi, Lim Jun Hyeok, Hong Yun Soo, Shin Kyeong-Cheol, Lee Chang Youl, Kim Do Jin, Lee Sang Haak, Jung Ki Suck, Lee Chang-Hoon, Yoo Kwang Ha, Lee Hyun, Park Hye Yun
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, South Korea.
Division of Pulmonology, Department of Internal Medicine, Inha University Hospital, Inha University School of Medicine, Incheon, South Korea.
J Thorac Dis. 2021 Feb;13(2):837-846. doi: 10.21037/jtd-20-1098a.
Forced vital capacity (FVC) has been suggested to be a good biomarker for decreased exercise performance in patients with chronic obstructive pulmonary disease (COPD). However, as FVC is highly correlated with forced expiratory volume in 1 second (FEV), the relationship between FVC and exercise capacity should be assessed within the category of FEV1, i.e., COPD severity. However, this was not considered in previous studies. Thus, limited data are available on the association between reduced FVC and exercise capacity measured by 6-min walk distance (6MWD) based on COPD severity.
We performed a cross-sectional study using data from the Korean COPD Subgroup Study (KOCOSS) cohort. We evaluated 1,386 patients with moderate (n=895) and severe-to-very severe (n=491) COPD. Reduced FVC was defined as FVC <80% predicted and short 6MWD as <350 m. Multivariable logistic regression was used to evaluate the association between reduced FVC and short 6MWD.
There were no significant differences in respiratory symptoms and quality of life between the patients with reduced FVC and those with preserved FVC. However, patients with reduced FVC had shorter 6MWD (30.5 cm in moderate and 34.5 cm in severe-to-very severe COPD) and higher BODE index scores than those with preserved FVC. The cubic spline model revealed 6MWD peaked around 93% predicted of FVC in moderate COPD, whereas FVC showed a positive association with 6MWD in severe-to-very severe COPD. Multivariable analyses showed that reduced FVC was significantly associated with short 6MWD in both moderate [adjusted odds ratio (aOR) =1.44, 95% confidence interval (CI): 1.03-2.02] and severe-to-very severe (adjusted OR =1.55, 95% CI: 1.01-2.40) COPD.
Reduced FVC was significantly associated with shorter 6MWD in moderate-to-very severe COPD patients, suggesting that reduced FVC might be reflective of 6MWD-measured exercise capacity in moderate-to-very severe COPD.
用力肺活量（FVC）被认为是慢性阻塞性肺疾病（COPD）患者运动能力下降的良好生物标志物。然而，由于FVC与1秒用力呼气容积（FEV）高度相关，FVC与运动能力之间的关系应在FEV1类别（即COPD严重程度）内进行评估。然而，以往的研究并未考虑这一点。因此，基于COPD严重程度，关于FVC降低与6分钟步行距离（6MWD）所测量的运动能力之间关联的数据有限。
我们使用韩国COPD亚组研究（KOCOSS）队列的数据进行了一项横断面研究。我们评估了1386例中度（n = 895）和重度至极重度（n = 491）COPD患者。FVC降低定义为FVC<预测值的80%，6MWD缩短定义为<350 m。采用多变量逻辑回归评估FVC降低与6MWD缩短之间的关联。
FVC降低的患者与FVC保留的患者在呼吸道症状和生活质量方面无显著差异。然而，FVC降低的患者6MWD较短（中度COPD患者为30.5 cm，重度至极重度COPD患者为34.5 cm），且BODE指数得分高于FVC保留的患者。三次样条模型显示，在中度COPD中，6MWD在FVC预测值约93%时达到峰值，而在重度至极重度COPD中，FVC与6MWD呈正相关。多变量分析显示，在中度[调整优势比（aOR）=1.44，95%置信区间（CI）：1.03 - 2.02]和重度至极重度（调整OR =1.55，95%CI：1.01 - 2.40）COPD中，FVC降低均与6MWD缩短显著相关。
在中度至极重度COPD患者中，FVC降低与较短的6MWD显著相关，这表明FVC降低可能反映了中度至极重度COPD患者通过6MWD测量的运动能力。
