[Prospective association between physical activity and mortality in patients with chronic obstructive pulmonary disease].

Abstract

Objective: To explore the prospective association between physical activity level and mortality risk in Chinese adults with chronic obstructive pulmonary disease (COPD).

Methods: Based on the China Kadoorie Biobank (CKB) who had COPD at the baseline survey, this study employed the Cox proportional hazards regression model to estimate the prospective associations between the overall physical activity, different intensities (low-level, moderate-to-vigorous-level), and types (occupational, non-occupational) of physical activity level and the risks of all-cause and cause-specific mortality, such as vascular diseases, cancer, and respiratory diseases. Based on the quintiles of physical activity level, participants were divided into five groups (Q1-Q5), with the lowest quintile group (Q1) as the reference group. Hazard ratio (HR) and 95% confidence interval (95%CI) were calculated for the remaining. In our study, we also performed sensitivity and subgroup analyses, including age, gender, self-rated health status, severity of COPD, etc.

Results: Among 33 588 COPD patients at the baseline survey, 8 314 (22.2%) deaths were documented during an average follow-up of (11.1±3.1) years. Negative linear associations between the overall physical activity level and mortality risk from all-cause, vascular, and respiratory diseases were observed (P trend for linear correlation being < 0.001, 0.002, < 0.001). Compared with the lowest quintile group of total physical activity (Q1), the hazard ratios (HR) and 95% confidence intervals (CI) for all-cause mortality, vascular disease mortality, and respiratory disease mortality in the highest quintile group (Q5) were 0.77 (0.70, 0.85), 0.77 (0.65, 0.91), and 0.58 (0.48, 0.71), respectively. The low-level and moderate-to-vigorous-level physical activity were negatively associated with all-cause mortality in the COPD patients (P trend for linear correlation: 0.002, < 0.001, respectively). Compared with the lowest quintile group of low-intensity and moderate-to-vigorous intensity physical activity (Q1), the HRs (95%CI) for all-cause mortality in the highest quintile group (Q5) were 0.89 (0.82, 0.97) and 0.79 (0.72, 0.87), respectively. The occupational and non-occupational physical activity were also found to have a linear inverse association with all-cause mortality risk among the COPD patients (P trend < 0.001 and 0.015, respectively). Compared with the lowest quintile group of occupational and non-occupational physical activity (Q1), the HR (95%CI) for all-cause mortality in the highest quintile group (Q5) were 0.69 (0.61, 0.78) and 0.91 (0.84, 0.98), respectively. The associations between overall physical activity and all-cause mortality risk were stronger for patients aged 60 and above, female, and who reported poor health status (P for interaction: 0.028, 0.012, 0.010). The protective effect of total physical activity was also applicable to the COPD patients of varying severity.

Conclusion: Physical activity could reduce the mortality risk in a dose-response relationship among COPD patients, regardless of its intensity and type, especially among individuals aged 60 and above, females, and those with poor self-report health status.