Association of Sitting Time with All-Cause and Cardiovascular Mortality: How Does Frailty Modify This Association?

To investigate how frailty modifies the association of sitting time with all-cause and cardiovascular mortality in Chilean adults. This prospective study included 2,604 participants aged ≥35 from the Chilean National Health Survey 2009-2010. Sitting time was self-reported, while frailty was assessed using a 36-item Frailty Index. Sitting time was categorized as low, medium, and high. Cox proportional hazard models were used to estimate the risk of mortality stratified for the sitting time categories. Over a median follow-up of 8.9 years, 311 participants died, 28% of them due to cardiovascular events. Frail people with prolonged sitting time were at higher risk of all-cause and cardiovascular mortality (hazard ratio 3.13; 95% confidence interval [2.06, 4.71] and hazard ratio 2.41; 95% confidence interval [1.50, 3.64], respectively). The observed risk was higher in women than men. Public health and individual strategies should be implemented to decrease sitting time across the population, with special attention on frail people.