High Sedentary Time Associated with Increased All-Cause Mortality, CVD Risk

Scott A. Lear, PhD

New findings suggest a high sitting time was significantly associated with an increased risk of all-cause mortality and cardiovascular disease (CVD) in economically diverse settings, particularly in low-income and lower-middle-income countries.

The findings supported global guidelines on sedentary behavior and indicated that physical activity may reduce the increased risk as a result of said behavior, according to investigators.

“Our findings emphasize that reducing sedentary time along with increasing physical activity may be an important strategy for easing the global burden of premature deaths and CVD,” wrote corresponding study authors Wei Li, PhD, National Center for Cardiovascular Diseases, Fuwai Hospital and Scott A. Lear, PhD, Faculty of Health Sciences, Simon Fraser University.

The commonality of modern society has led to increased sitting time, as a result of electronic use, an increase in sedentary occupations, and changing patterns of transportation. However, evidence has been exclusively reported in high-income countries and China and it is known whether the same risks can be observed in low- and middle-income countries.

This analysis thus aimed to determine the association of self-reported sitting time with all-cause mortality and major CVD in countries at varying income levels utilizing data from the Prospective Urban Rural Epidemiology study. It included individuals aged 35 - 70 years across regions of Africa, Asia, Europe, the Middle East, and North and South America recruited from January 2003, with follow-up until August 2021.

Their daily sitting time was measured using the International Physical Activity Questionnaire and the composite of all-cause death and major CVD made up the main outcome.

From a total of 105,677 participants included in the analysis, 61,925 were women (58.6%) and the mean age was 50.4 years. Data show the median sitting time at baseline was 4.0 hours per day, with a range of 2.6 hours per day in Poland and Chile to 7.3 hours per day in Saudi Arabia, investigators said.

Over a median follow-up of 11.1 years, investigators recorded 6233 deaths and 5696 major cardiovascular events, consisting of 2349 myocardial infarctions, 2966 strokes, 671 heart failure, and 1792 cardiovascular deaths.

The risk of the composite outcome associated with sitting time was significantly increased above 6 hours per day (hazard ratio [HR], 1.13, 95% CI, 1.06 - 1.21 for 6 - 8 hours per day; HR, 1.19, 95% CI, 1.11 - 1.28 for ≥8 hours per day; P for trend <.001).

Moreover, sitting more than 8 hours per day had an association with an HR of 1.20 (95% CI, 1.10 = 1.31) for all-cause mortality and 1.21 (95% CI, 1.10 -1.34) for major CVD, according to the investigators.

If stratified by country income level, the the association of sitting time with the composite outcome was stronger in low-income and lower-middle-income countries (8 hours per day; HR, 1.29; 95% CI, 1.16 - 1.44), compared to high-income and upper-middle-income countries (HR, 1.08; 95% CI, 0.98 - 1.19; P for interaction = .02).

Further, in individuals who sat for 8 or more hours per day, the hazard of the composite outcome was increased by between 17% and 50% across physical activity levels. Investigators noted the risk was attenuated with increased physical activity levels.

The study, “Association of Sitting Time with Mortality and Cardiovascular Events in High-Income, Middle-Income, and Low-Income Countries,” was published in JAMA Cardiology.