Joint association of physical activity and sedentary time with all-cause and cardiovascular mortality among advanced CKM syndrome participants, insights from NHANES 2007–2018

Cardiovascular-kidney-metabolic (CKM) syndrome represents the interconnection of metabolic dysfunction, chronic kidney disease, and cardiovascular disease, with advanced stages associated with high mortality. However, the associations of leisure-time physical activity (PA) and sedentary time with mortality in participants with advanced CKM syndrome remain unclear. This study conducted a prospective cohort study using data from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2018. Multivariate Cox proportional hazards models, restricted cubic spline (RCS) analyses, and subgroup analyses were applied to examine the independent and joint associations of leisure-time PA and sedentary time with all-cause and cardiovascular mortality among participants with advanced CKM syndrome. Among advanced CKM participants, physical inactivity was associated with higher risks of all-cause (HR = 2.43, 95% CI: 1.98–2.97, P < 0.001) and cardiovascular mortality (HR = 2.62, 95% CI: 1.79–3.82, P < 0.001). Compared with < 4 h/day, sedentary time > 8 h/day was independently linked to elevated risks of all-cause (HR = 1.71, 95% CI: 1.33–2.19, P < 0.001) and cardiovascular mortality (HR = 2.12, 95% CI: 1.34–3.38, P = 0.005). Joint analyses showed that the group characterized by physical inactivity combined with ≥ 6 h/day sedentary time was associated with the highest risk of all-cause (HR = 2.77, 95% CI: 2.16–3.56, P < 0.001) and cardiovascular mortality (HR = 3.39, 95% CI: 2.13–5.40, P < 0.001). These associations were further supported by RCS analyses and sensitivity analyses. The findings underscore the potential survival advantages associated with enhancing physical activity and reducing sedentary behavior in this high-risk population.