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Do the associations of sedentary behaviour with cardiovascular disease mortality and cancer mortality differ by physical activity level? A systematic review and harmonised meta-analysis of data from 850 060 participants
  1. Ulf Ekelund1,2,
  2. Wendy J Brown3,
  3. Jostein Steene-Johannessen1,4,
  4. Morten Wang Fagerland1,5,
  5. Neville Owen6,7,
  6. Kenneth E Powell8,
  7. Adrian E Bauman9,
  8. I-Min Lee10,11
  1. 1 Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway
  2. 2 Department for Chronic Diseases and Ageing, Norwegian Institute of Public Health, Oslo, Norway
  3. 3 Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
  4. 4 Department of Health Sciences, Kristiania University College, Oslo, Norway
  5. 5 Oslo Centre for Biostatistics and Epidemiology, Research Support Services, Oslo University Hospital, Oslo, Norway
  6. 6 Behavioural Epidemiology, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
  7. 7 Health, Arts and Design, Swinburne University of Technology, Melbourne, Victoria, Australia
  8. 8 Retired
  9. 9 Prevention Research Collaboration, School of Public Health and Charles Perkins Centre, Sydney University, Sydney, New South Wales, Australia
  10. 10 Division of Preventive Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
  11. 11 Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
  1. Correspondence to Professor Ulf Ekelund, Department of Sport Medicine, Norwegian School of Sport Sciences, Olso 0806, Norway; Ulf.Ekelund{at}nih.no

Abstract

Objective To examine whether the associations between sedentary behaviours (ie, daily sitting/TV-viewing time) and mortality from cardiovascular disease (CVD) and cancer differ by different levels of physical activity (PA).

Design Harmonised meta-analysis of prospective cohort studies. Data on exposure variables were harmonised according to a predefined protocol and categorised into four groups for sedentary behaviours and into quartiles of PA (MET-hour/week).

Data sources PubMed, PsycINFO, Embase, Web of Science, Sport Discus and Scopus.

Eligibility criteria for selecting studies Individual level data on both sedentary behaviours and PA and reported effect estimates for CVD or cancer mortality.

Results Nine studies (n=850 060; deaths=25 730) and eight studies (n=777 696; deaths=30 851) provided data on sitting time and CVD and cancer mortality, respectively. Five studies had data on TV-viewing time and CVD (n=458 127; deaths=13 230) and cancer (n=458 091; deaths=16 430) mortality. A dose–response association between sitting time (9%–32% higher risk; p for trend <0.001) and TV time (3%–59% higher risk; p for trend <0.001) with CVD mortality was observed in the ‘inactive’, lowest quartile of PA. Associations were less consistent in the second and third quartiles of PA, and there was no increased risk for CVD mortality with increasing sedentary behaviours in the most active quartile. Associations between sedentary behaviours and cancer mortality were generally weaker; 6%–21% higher risk with longer sitting time observed only in the lowest quartile of PA.

Conclusion PA modifies the associations between sedentary behaviours and CVD and cancer mortality. These findings emphasise the importance of higher volumes of moderate and vigorous activity to reduce, or even eliminate these risks, especially for those who sit a lot in their daily lives.

  • physical activity
  • sedentary
  • cardiovascular
  • cancer
  • sitting time

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Footnotes

  • Contributors All authors contributed to the design of the study, generated hypotheses, interpreted the data and wrote and critically reviewed the report. UE lead the work of the writing group and wrote the first draft of the manuscript. JS-J and UE did the literature search. MWF analysed the data. MWF, JS-J, and UE had full access to study level data from all contributing studies.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Not required.

  • Ethics approval This is a systematic review and meta-analysis of studies which all have been individually approved by their respective ethical review boards.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement We can not share any data as we do not have access to individual level data from participating studies.

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