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Sitting for hours can increase CVD risk, hasten death – cohort study

Recent research has confirmed opinions that prolonged sitting may be hazardous to your health. An international study surveying more than 100,000 people in 21 countries found that those who sat for six to eight hours a day had a 12%-13% increased risk of early death and heart disease, while those who sat for more than eight hours daily increased that to a sobering 20%.

Not surprising, those who sat the most and were the least active had the highest risk – up to 50% – while those who sat the most but were also the most active had a substantially lower risk of about 17%.

The study, co-led by Canada’s Simon Fraser University health sciences professor, Scott Lear, and Wei Li of Beijing’s Chinese Academy of Medical Sciences, followed people over an average of 11 years and determined that long periods of sitting were associated with increased risk of early death and cardiovascular disease.

While sitting was problematic in all countries, it was especially so in low-income and lower-middle-income countries.

“The overarching message here is to minimise how much you sit,” said Lear. “If you must sit, getting in more exercise during other times of the day will offset that risk. For those sitting more than four hours a day, replacing a half hour of sitting with exercise reduced the risk by two per cent.”

The study found a particular association in lower income countries, leading researchers to speculate that it may be because sitting in higher income countries is typically associated with higher socio-economic status and better paying jobs.

Clinicians should focus on less sitting and more activity as it’s a low-cost intervention that can have enormous benefit, Lear said.

But while clinicians needed to spread the message about countering sitting with activity, people needed to better assess their lifestyles and take their health seriously.

“Our study found that a combination of sitting and inactivity accounted for 8.8% of all deaths, close to the contribution of smoking (10.6% in Lear and Li’s study). It's a global problem that has a remarkably simple fix. Scheduling time to get out of that chair is a great start.”

Study details
Association of Sitting Time With Mortality and Cardiovascular Events in High-Income, Middle-Income, and Low-Income Countries

Sidong Li, Scott A. Lear, Sumathy Rangarajan, Bo Hu, Lu Yin, Shrikant I. Bangdiwala, Khalid F. Alhabib, Annika Rosengren, Rajeev Gupta, Prem K. Mony, Andreas Wielgosz, Omar Rahman, M. Y. Mazapuspavina, Alvaro Avezum, Aytekin Oguz, Karen Yeates, Fernando Lanas, Antonio Dans, Marc Evans M. Abat, Afzalhussein Yusufali, Rafael Diaz, Patricio Lopez-Jaramillo, Lloyd Leach, P. V. M. Lakshmi, Alicja Basiak-Rasała, Romaina Iqbal, Roya Kelishadi, Jephat Chifamba, Rasha Khatib, Wei Li, Salim Yusuf.

Published in JAMA Cardiology on 15 June 2022.

Key Points
Question Is daily sitting time associated with mortality and cardiovascular disease (CVD) in countries of different economic levels?
Findings In this cohort study including 105,677 participants from 21 countries, higher sitting time was associated with an increased risk of all-cause mortality and major CVD, and the association was more pronounced in low-income and lower-middle–income countries. Meeting the World Health Organization recommendations for physical activity could effectively attenuate the risk of high sitting time.
Meaning Reducing sedentary time along with increasing physical activity may be an important strategy for easing the global burden of premature deaths and CVD.

Abstract

Importance
High amounts of sitting time are associated with increased risks of cardiovascular disease (CVD) and mortality in high-income countries, but it is unknown whether risks also increase in low- and middle-income countries.

Objective
To investigate the association of sitting time with mortality and major CVD in countries at different economic levels using data from the Prospective Urban Rural Epidemiology study.

Design, Setting, and Participants
This population-based cohort study included participants aged 35 to 70 years recruited from January 1, 2003, and followed up until August 31, 2021, in 21 high-income, middle-income, and low-income countries with a median follow-up of 11.1 years.

Exposures
Daily sitting time measured using the International Physical Activity Questionnaire.

Main Outcomes and Measures
The composite of all-cause mortality and major CVD (defined as cardiovascular death, myocardial infarction, stroke, or heart failure).

Results
Of 105,677 participants, 61 925 (58.6%) were women, and the mean (SD) age was 50.4 (9.6) years. During a median follow-up of 11.1 (IQR, 8.6-12.2) years, 6,233 deaths and 5,696 major cardiovascular events (2,349 myocardial infarctions, 2,966 strokes, 671 heart failure, and 1,792 cardiovascular deaths) were documented. Compared with the reference group (<4 hours per day of sitting), higher sitting time (≥8 hours per day) was associated with an increased risk of the composite outcome (hazard ratio [HR], 1.19; 95% CI, 1.11-1.28; Pfor trend < .001), all-cause mortality (HR, 1.20; 95% CI, 1.10-1.31; Pfor trend < .001), and major CVD (HR, 1.21; 95% CI, 1.10-1.34; Pfor trend < .001). When stratified by country income levels, 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 with high-income and upper-middle–income countries (HR, 1.08; 95% CI, 0.98-1.19; P for interaction = .02). Compared with those who reported sitting time less than 4 hours per day and high physical activity level, participants who sat for 8 or more hours per day experienced a 17% to 50% higher associated risk of the composite outcome across physical activity levels; and the risk was attenuated along with increased physical activity levels.

Conclusions and relevance
High amounts of sitting time were associated with increased risk of all-cause mortality and CVD in economically diverse settings, especially in low-income and lower-middle–income countries. Reducing sedentary time along with increasing physical activity might be an important strategy for easing the global burden of premature deaths and CVD.

 

JAMA Cardiology article – Association of Sitting Time With Mortality and Cardiovascular Events in High-Income, Middle-Income, and Low-Income Countries (Open access)

 

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