Abstract
BackgroundRegular physical activity is recommended for all people with chronic obstructive pulmonary disease (COPD), but the dose of physical activity required to gain mortality benefit in this population is not yet known. This aim of this study was to examine the associations of total and type-specific physical activity with mortality risk in people with COPD.MethodsPeople with COPD aged ≥40 years were identified from the 1997 Health Survey for England and the 1998 and 2003 Scottish Health Survey cohorts. Self-reported total physical activity, moderate-vigorous intensity physical activity (MVPA), walking, domestic physical activity, and sport/exercise were assessed at baseline. Cox proportional hazards models were used to examine the associations between physical activity and mortality risk.ResultsTwo thousand three hundred ninety-eight participants with COPD were included in the analysis and followed up for a mean 8.5 (SD 3.9) years. For both total physical activity and MVPA, we observed dose-response associations with all-cause and cardiovascular disease (CVD) mortality risk, and with respiratory mortality risk to a lesser extent. Compared to those who reported no physical activity, participants who met the physical activity guidelines demonstrated the greatest reductions in all-cause (HR 0.56, 95% CI 0.45–0.69), CVD (HR 0.48, 95% CI 0.32–0.71) and respiratory mortality risk (HR 0.40, 95% CI 0.24–0.67). Participants who reported a level of physical activity of at least half the dosage recommended by the guidelines also had a reduced risk of all-cause (HR 0.75, 95% CI 0.56–1.00) and CVD mortality (HR 0.48, 95% CI 0.26–0.88). Dose-response associations with mortality risk were demonstrated for walking and sport/exercise, but not domestic physical activity.ConclusionsWe found a dose-response association between physical activity and all-cause and CVD mortality risk in people with COPD, with protective effects appearing at levels considerably lower than the general physical activity recommendations. People with COPD may benefit from engagement in low levels of physical activity, particularly walking and structured exercise.
Highlights
Regular physical activity is recommended for all people with chronic obstructive pulmonary disease (COPD), but the dose of physical activity required to gain mortality benefit in this population is not yet known
Cheng et al BMC Public Health (2018) 18:268. Compared to their healthy peers, people with chronic obstructive pulmonary disease (COPD) engage in a lower intensity of daily physical activity (PA), and spend significantly more time sitting and lying down [1, 2]. This has been attributed to disease-specific limitations such as dyspnoea, fatigue and reduced exercise tolerance, which reduce the capacity of people with COPD to engage in moderate-vigorous intensity physical activity (MVPA) [3]
After taking the sensitivity analyses into consideration, which yielded similar mortality risk reductions in participants without existing cardiovascular disease (CVD), cancer and diabetes, these results suggest that the dose of PA required to gain mortality benefit in COPD may be lower than is currently estimated
Summary
Regular physical activity is recommended for all people with chronic obstructive pulmonary disease (COPD), but the dose of physical activity required to gain mortality benefit in this population is not yet known. A Spanish cohort study of 611 people with COPD found that those who “took walks regularly for >8 km, no less than 5 days a week, or practised sports” had a lower mortality risk compared to those who “don’t leave the house and life is limited to the bed or armchair, or to doing some domestic chores” (risk ratio (RR) 0.38, 95% confidence interval (CI) 0.11–1.29) [7] Another cohort study of 173 people with moderate to very severe COPD, which used accelerometry to measure PA levels, found that every ten vector-magnitude unit (VMU) increase in daily PA was associated with a 14% reduction in mortality risk [8]. Many different questionnaires and activity monitors have been used to assess PA in people with COPD, and the optimal mode of reporting (e.g., energy expenditure, number of steps/day) is not yet known [4, 9]
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