Exercise-Induced Oxygen Desaturation as a Predictive Factor for Longitudinal Decline in 6-Minute Walk Distance in Subjects With COPD

• Published in: Respiratory care 2019-02, Vol.64 (2), p.145-152
• Main Authors: Misu, Shogo, Kaneko, Masahiro, Sakai, Hideki, Oki, Yutaro, Fujimoto, Yukari, Ishikawa, Akira, Ono, Rei
• Format: Article
• Language: English
• Subjects: Activities of daily living; Aged; Chronic obstructive lung disease; Exercise; Exercise - physiology; Exercise Tolerance; Female; Health aspects; Humans; Linear Models; Longitudinal Studies; Male; Medical research; Oxygen consumption (Metabolism); Oxygen Consumption - physiology; Predictive Value of Tests; Prognosis; Pulmonary Disease, Chronic Obstructive - physiopathology; Regression analysis; Spirometry; Vital Capacity; Walk Test - statistics & numerical data
• ISSN: 0020-1324; 1943-3654
• DOI: 10.4187/respcare.06169

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.