How much time spent per day in sedentary behavior increases mortality risk in patients with COPD

Background: The terms “sedentary behaviour” and “physical inactivity” have been confusingly mixed. Although the association between physical inactivity and mortality has been previously shown in patients with chronic obstructive pulmonary disease (COPD), this association was not yet investigated concerning sedentarism. Aims: To propose a cut-off point for sedentarism in patients with COPD and to investigate its association with mortality. Methods: In this retrospective cohort study, sedentary behaviour was assessed with two activity monitors (DynaPort and Sensewear armband) in 101 patients with COPD from 2006 to 2011. Vital status was then ascertained in 2015. Cut-off points for sedentarism and their respective prognostic values were investigated for the following six variables: average of MET/day and time spent/day lying, sitting, lying+sitting and in activities requiring Results: Forty-one patients (41%) died over a median (25-75%IQR) follow-up period of 62(43-88) months. After adjusting for potential confounders in the Cox regression model, the strongest independent cut off for predicting mortality was ≥8:30 hours/day spent in sedentary activities P =0.001). Each hour/day spent P =0.03). Conclusion: Mortality is higher in patients with COPD who spend more than 8:30 hours/day in activities requiring