Assessing the causal role of physical activity and leisure sedentary behaviours with chronic obstructive pulmonary disease: a Mendelian randomisation study.

backgroundObservational studies show that patients with chronic obstructive pulmonary disease (COPD) tend to be sedentary during leisure time. Physical activity (PA) may reduce the risk of COPD, but the causal relationship is unclear. We used a Mendelian randomisation (MR) method to elucidate the association of leisure sedentary behaviours (LSB) and PA with lung function and COPD.

methodsData on LSB (n=422 218), PA (n=608 595), COPD (n=299 929) and lung function (n=79 055) were obtained from the large-scale genome-wide association study. Causal inference used inverse variance-weighted, MR-Egger and weighted median. Sensitivity analysis was performed to assess heterogeneity and pleiotropy, and radial MR was used to distinguish outliers. The primary outcome was analysed by multifactorial MR adjusted for daily smoking.

resultsThe inverse variance weighted analysis indicated that increased moderate-to-vigorous PA (MVPA) is associated with higher levels of forced vital capacity (FVC) (beta=0.27, 95% CI 0.12 to 0.42; p=3.51×10

conclusionsOur study suggests a potential association with LSB, particularly television watching, is associated with higher odds of COPD and lower indices of lung function as measured continuously, including FEV1 and FVC. Conversely, an increase in MVPA is associated with higher indices of lung function, particularly reflected in increased FVC levels.