Changhwan Kim1, Yousang Ko2, Jae Seung Lee3, Chin Kook Rhee4, Jin Hwa Lee5, Ji-Yong Moon6, Seong Yong Lim7, Kwang Ha Yoo8, Joon Beom Seo9, Yeon-Mok Oh3, Sang-Do Lee3, Yong Bum Park10. 1. Department of Internal Medicine, Jeju National University Hospital, Jeju National University School of Medicine, Jeju, Republic of Korea; Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea. 2. Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea; Department of Pulmonary and Critical Care Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Republic of Korea. 3. Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea; Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. 4. Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea; Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. 5. Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea; Department of Internal Medicine, Ewha Womans University Seoul Hospital, College of Medicine, Ewha Womans University, Seoul, Republic of Korea. 6. Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea; Division of Pulmonology, Department of Internal Medicine, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, Republic of Korea. 7. Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea; Division of Pulmonary and Critical Care Medicine, Department of Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. 8. Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea; Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Republic of Korea. 9. Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea; Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. 10. Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea; Department of Pulmonary and Critical Care Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Republic of Korea. Electronic address: bfspark2@gmail.com.
Abstract
BACKGROUND: There are few reports on exercise-induced desaturation (EID) as a predictor of mortality in chronic obstructive pulmonary disease (COPD). However, the definitions of EID vary in published reports. The main purpose was to evaluate the association between EID and long-term mortality by applying two criteria of EID. METHODS: A total of 507 subjects were selected from the Korean Obstructive Lung Disease cohort. EID was assessed using the 6-min walk test (6MWT) and defined using two different criteria [1]: post-6MWT oxygen saturation (SpO2) of ≤88% (criterion A) and [2] post-6MWT SpO2 < 90% or a decrease of ≥4% compared to baseline (criterion B). RESULTS: The prevalence of EID was 5.1% based on criterion A and 13.0% based on criterion B. Regardless of the criteria used, mortality was higher in the EID group than in the non-EID group (A: 50 vs. 11.4%, B: 33.3 vs. 10.4%) during up to 161 months of follow-up. COPD patients without EID survived significantly longer than those with EID (A: 143.5 vs. 92.9, B: 144.8 vs. 115.2 months). Multivariate Cox regression analysis revealed that COPD patients with EID had a 2.4-fold increased risk of death by criterion A (adjusted HR 2.375; 95% CI: 1.217-4.637; P = 0.011). The risk of death increased in COPD patients with EID by criterion B, but the difference was not statistically significant. CONCLUSIONS: COPD patients with EID demonstrated significantly higher long-term mortality than those without EID. The EID criterion A has a better predictive value for mortality in COPD.
BACKGROUND: There are few reports on exercise-induced desaturation (EID) as a predictor of mortality in chronic obstructive pulmonary disease (COPD). However, the definitions of EID vary in published reports. The main purpose was to evaluate the association between EID and long-term mortality by applying two criteria of EID. METHODS: A total of 507 subjects were selected from the Korean Obstructive Lung Disease cohort. EID was assessed using the 6-min walk test (6MWT) and defined using two different criteria [1]: post-6MWT oxygen saturation (SpO2) of ≤88% (criterion A) and [2] post-6MWT SpO2 < 90% or a decrease of ≥4% compared to baseline (criterion B). RESULTS: The prevalence of EID was 5.1% based on criterion A and 13.0% based on criterion B. Regardless of the criteria used, mortality was higher in the EID group than in the non-EID group (A: 50 vs. 11.4%, B: 33.3 vs. 10.4%) during up to 161 months of follow-up. COPD patients without EID survived significantly longer than those with EID (A: 143.5 vs. 92.9, B: 144.8 vs. 115.2 months). Multivariate Cox regression analysis revealed that COPD patients with EID had a 2.4-fold increased risk of death by criterion A (adjusted HR 2.375; 95% CI: 1.217-4.637; P = 0.011). The risk of death increased in COPD patients with EID by criterion B, but the difference was not statistically significant. CONCLUSIONS: COPD patients with EID demonstrated significantly higher long-term mortality than those without EID. The EID criterion A has a better predictive value for mortality in COPD.