Abstract: Objective To explore potential association between sedentary time and the risk of all-cause mortality and cardiovascular disease (CVD) in Chinese population using data from the Prospective Urban Rural Epidemiology (PURE-China) cohort study. Methods Baseline data were collected, from 2022 standardized questionnaires and physical examinations, with follow-up until August 31, 2022. The primary endpoints were all-cause mortality and cardiovascular events (non-fatal myocardial infarction, stroke or heart failure). Multivariable Cox shared frailty model was used to analyze the association between sedentary time and the risks of all-cause mortality and CVD in the target population, and to compare differences across subgroups based on gender, age and geographic location. Results A total of 47 931 participants were recruited, and 43 367 were included in the final analysis. Over a median follow-up of 11.9±3.0 years, 2 277 participants experienced all-cause mortality, 3 551 experienced cardiovascular events. The Cox model indicated that, compared to individuals with less than 4 h of sedentary time per day, those with 6-8 h had a 23% increased in risk of all-cause mortality (HR=1.23, 95% CI: 1.06-1.44) and an 18% increased risk of CVD (HR=1.18, 95% CI: 1.04-1.33). For individuals with more than 8 h of sedentary time, the risk increased by 50% for all-cause mortality (HR=1.50, 95% CI: 1.16-1.94) and 44% for CVD(HR=1.44, 95% CI: 1.16-1.79). These associations were more pronounced in men and individuals aged 50 years and older. Conclusions Sedentary behavior is associated with an increased risk of all-cause mortality and cardiovascular disease in Chinese population, especially in the population with sedentary time of 6 hrs or more per day. Reducing sedentary time and increasing physical activity is an important strategy to mitigate the disease burden of cardiovascular disease and premature death.

Key words: sedentary behavior, cardiovascular disease, cohort study, all-cause mortality, hazard ratio