Association of sedentary time with risk of cardiovascular diseases and cardiovascular mortality: A systematic review and meta-analysis of prospective cohort studies

Given the high prevalence of cardiovascular disease (CVD), we meta-analysed CVD relative risk (RR) in relation to high vs. low categories of self-reported and objectively assessed sedentary behaviours from cohort studies; in a sub-sample (n = 4 studies), the theoretical substitution of one hour spent sedentary with the same amount of time spent in light-intense physical activity was evaluated. Based on 19 studies (60,526 fatal and non-fatal CVD, 1,473,354 individuals and 13,559,139 persons-year) we estimated a 30% increased CVD risk for high vs. low categories of sedentary behaviour (RR = 1.29, confidence interval (CI) = 1.22;1.37). Every hour spent sedentary corresponds to a 5% increased fatal and non-fatal CVD risk (RR = 1.05, CI = 1.02;1.07). Dose-response meta analysis revealed that sedentary behaviour is statistically significantly associated to fatal and non-fatal CVD risk following a J-shaped relation. Substituting one hour spent sedentary with physical activity of light intensity reduced the risk of fatal and non-fatal CVD events by one-fifth (RR =0.84, CI = 0.73;0.97). In meta-regression analysis, potential influential factors such as age, sex, and medical condition did not essentially alter the results.