Department of Community Health Sciences, Kobe University Graduate School of Health Sciences, Kobe, Japan.
Department of Physical Therapy, Faculty of Nursing and Rehabilitation, Konan Women's University, Kobe, Japan.
Respir Care. 2019 Feb;64(2):145-152. doi: 10.4187/respcare.06169. Epub 2018 Oct 16.
There are limited longitudinal studies reporting predictive factors for decline in 6-min walk distance (6MWD) in patients with COPD. While previous studies have confirmed the association between air-flow limitation and decline in 6MWD, other factors have not been clarified. The objective of this study was to investigate whether exercise-induced oxygen desaturation (EID) could be a predictive factor for decline in 6MWD in patients with COPD. The interactive effect of air-flow limitation on the association between EID and decline in 6MWD was also investigated.
A longitudinal observational study was conducted with 71 out-patients with COPD who were followed for 1 year. 6MWD, EID, spirometry, and clinical characteristics were assessed. The effect of EID on changes in 6MWD was examined using linear regression analyses. Furthermore, the subjects were categorized into 4 groups according to their EID and air-flow limitation status, and changes in 6MWD were compared among the groups.
51 subjects completed the follow-up assessments, and 29 (56.9%) experienced EID. Multiple linear regression model revealed that EID was the only predictive factor for changes in 6MWD after adjusting for confounders (β = -38.9, = .02). As results of multiple comparisons among the 4 groups based on EID and air-flow limitation status, changes in 6MWD in the EID and severe air-flow limitation group were the lowest.
Our results revealed that EID was a predictive factor for decline in the functional capacity of subjects with COPD. The assessment of EID and air-flow limitation would thus be useful in estimating the prognosis of decline in the functional capacity of patients with COPD.
目前仅有少数纵向研究报告了慢性阻塞性肺疾病（COPD）患者 6 分钟步行距离（6MWD）下降的预测因素。虽然既往研究已经证实气流受限与 6MWD 下降之间存在关联，但其他因素尚不清楚。本研究旨在探讨运动诱导的血氧饱和度下降（EID）是否可以作为 COPD 患者 6MWD 下降的预测因素。还研究了气流受限对 EID 与 6MWD 下降之间关联的交互作用。
对 71 例 COPD 门诊患者进行了一项纵向观察性研究，随访时间为 1 年。评估了 6MWD、EID、肺功能和临床特征。使用线性回归分析检查了 EID 对 6MWD 变化的影响。此外，根据 EID 和气流受限状态将受试者分为 4 组，并比较了各组 6MWD 的变化。
51 例患者完成了随访评估，其中 29 例（56.9%）发生了 EID。多线性回归模型显示，在调整混杂因素后，EID 是 6MWD 变化的唯一预测因素（β=-38.9，P=.02）。根据 EID 和气流受限状态对 4 组进行多重比较的结果，EID 和严重气流受限组的 6MWD 变化最低。
我们的结果表明，EID 是 COPD 患者功能能力下降的预测因素。因此，评估 EID 和气流受限有助于估计 COPD 患者功能能力下降的预后。
