Association Between Sitting Time and Physical Activity With Survival Among Stroke Survivors: A National Cohort Study

To assess the independent and joint effects of sitting time and moderate-to-vigorous intensity physical activity (MVPA) on mortality in stroke survivors.

Retrospective study of prospective cohort data from the National Health and Nutrition Examination Survey (NHANES) 2007-2018.

NHANES, a nationally representative US survey that combines in-home interviews and standardized physical examinations conducted in mobile examination centers.

A total of 1312 adult stroke survivors were included, representing a weighted population of 6617,365 individuals. Participants were followed for mortality outcomes through December 31, 2019.

Not applicable.

All-cause and cardiovascular disease (CVD)-specific mortality ascertained from the National Death Index.

Over a median follow-up of 4.85 years, there were 438 deaths, including 151 because of CVD. Sitting ≥8 h/d was associated with higher risks of all-cause mortality (hazard ratio [HR], 1.73; 95% confidence interval [CI], 1.25-2.40) and CVD-specific mortality (HR, 1.97; 95% CI, 1.04-3.74). A statistically significant interaction between sitting time and MVPA was observed for all-cause mortality (P for interaction=.006). Participants with both prolonged sitting and <150 min/wk of MVPA had significantly increased risks of all-cause mortality (HR, 3.86; 95% CI, 2.20-6.78), compared with stroke survivors who were sufficiently active and reported shorter sitting time (MVPA ≥150min/wk and sitting time <4h/d). Importantly, the association between prolonged sitting and increased all-cause mortality was observed only among those with insufficient MVPA (HR, 1.04; 95% CI, 1.01-1.07), but not among those who were sufficiently active (HR, 1.00; 95% CI, 0.91-1.10).

This study of US stroke survivors reveals that the combination of insufficient physical activity and prolonged sitting is associated with the highest mortality risk, and sufficient MVPA may attenuate the all-cause mortality risk associated with prolonged sitting.