Effect of physical activity on mortality and hospitalization for lower respiratory tract infection in patients with cardiovascular disease
Abstract Background Despite the well-validated benefit of physical activity on various health outcomes, little is known about its effect on lower respiratory tract infection. We explored the dose-response associations between physical activity and lower respiratory tract infection outcomes in patients with cardiovascular disease. Methods Using the Korean National Health Insurance data, we identified more than 1 million individuals with cardiovascular diseases who had data on self-reported physical activity (baseline 2009–2012). Participants were followed up until 2018–2019 regarding the risk of death or hospitalization due to lower respiratory tract infection according to their physical activity level. Results Age- and sex-adjusted hazard ratios (95% confidence interval) for lower respiratory tract infection mortality were 1.00 (reference), 0.70 (0.67–0.74), 0.63 (0.59–0.66), 0.48 (0.43–0.53), and 0.51 (0.45–0.56) for those engaging in physical activity of 0, <500, 500–999, 1000–1499, and ≥1500 MET min/week, respectively. This was similarly applied to hospitalization due to lower respiratory tract infection. Generally, the association was stronger in the elderly population than in the younger population. Restricted cubic spline curve showed a non-linear association, that is, gradual risk reduction with a steeper slope between 0 and 500 MET min/week, reaching a plateau for 1500–1800 MET/min, and the curve flattened out thereafter. Conclusions In patients with cardiovascular disease, engaging in even low level of physical activity was associated decreased risk for lower respiratory tract infection outcomes and incremental risk reduction was shown with an increasing physical activity. FUNDunding Acknowledgement Type of funding sources: None.