The overlooked role of physical activity in mitigating the mortality risk in smokers and nonsmokers with COPD

Background Chronic obstructive pulmonary diseases (COPD), found in smokers and nonsmokers, are known to have increased mortality, but most people with COPD are unaware of their condition. They have a reduced exercise capacity and in general are less physically active, even though long-term benefits of physical activity have been demonstrated. Methods A total of 386,304 people participated in a health surveillance program between 1994 and 2008 in Taiwan. Lung function, blood tests, and medical history data, including smoking and exercise habits, were collected. Corresponding mortality and cancer data were retrieved from the National Death File and the National Cancer Registry, respectively. COPD was diagnosed by spirometry, as recommended by GOLD standard Results In a mean of 8.8-year follow-up, the prevalence of smokers and non-smokers with COPD was 5.3% and 3.7% respectively. Using Cox proportional hazard regression with factor adjustment, hazard ratio (HR) were 1.56 (1.46-1.66) in smoker, 1.48 (1.36-1.62) in those with COPD and 2.14 (1.97-2.34) in smokers with COPD. In those with COPD, fully active LTPA (>30 min/day), regardless of history of smoking, can reduce the all-cause mortality compared with inactive LTPA (<15min/day). For all-cause mortality in those without COPD or cardiovascular disease-related mortality in those with COPD, low active LTPA (15-30 min/day) can decrease the HR compared with the corresponding group. The active LTPA may extend the estimated life expectancy about 3 years in participants with COPD. Conclusions COPD is a systemic disease, causing non-lung related excess mortality such as CVD and cancer, and shortening life by 6 years. These excesses could be substantially mitigated by regular physical activity for 30 or more minutes/day of moderate intensity.