Objectives To examine the joint associations of accelerometer-measured physical activity and sedentary time with all-cause mortality.
Methods We conducted a harmonised meta-analysis including nine prospective cohort studies from four countries. 44 370 men and women were followed for 4.0 to 14.5 years during which 3451 participants died (7.8% mortality rate). Associations between different combinations of moderate-to-vigorous intensity physical activity (MVPA) and sedentary time were analysed at study level using Cox proportional hazards regression analysis and summarised using random effects meta-analysis.
Results Across cohorts, the average time spent sedentary ranged from 8.5 hours/day to 10.5 hours/day and 8 min/day to 35 min/day for MVPA. Compared with the referent group (highest physical activity/lowest sedentary time), the risk of death increased with lower levels of MVPA and greater amounts of sedentary time. Among those in the highest third of MVPA, the risk of death was not statistically different from the referent for those in the middle (16%; 95% CI 0.87% to 1.54%) and highest (40%; 95% CI 0.87% to 2.26%) thirds of sedentary time. Those in the lowest third of MVPA had a greater risk of death in all combinations with sedentary time; 65% (95% CI 1.25% to 2.19%), 65% (95% CI 1.24% to 2.21%) and 263% (95% CI 1.93% to 3.57%), respectively.
Conclusion Higher sedentary time is associated with higher mortality in less active individuals when measured by accelerometry. About 30–40 min of MVPA per day attenuate the association between sedentary time and risk of death, which is lower than previous estimates from self-reported data.
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Correction notice This article has been corrected since it published Online First. A typographical error in the title has been corrected.
Contributors UE led the work of the writing group (JT, MWF, JSJ, BHH, SAA and I-ML) and wrote the manuscript. MWF and JT analysed the data. MWF, JT and UE had full access to study level data from all contributing studies. All authors contributed to the design of the study, interpreted the data and critically reviewed the report.
Funding The individual studies contributing to this harmonised meta-analysis were funded from the following sources: The ABC-study was funded by Stockholm County Council, the Swedish National Centre for Research in Sports and the project ALPHA, which received funding from the European Union in the framework of the Public Health Programme and Folksam Research Foundation, Sweden; The British Regional Heart Study was funded by project and programme grants from the British Heart Foundation (PG/13/86/30546 and RG/13/16/30528); The EPIC Norfolk study has received funding from the UK Medical Research Council (MR/N003284/1), Cancer Research UK (C864/A14136), and the NIHR Biomedical Research Centre in Cambridge (IS-BRC-1215–20014); PCD is supported by a National Health and Medical Research Council of Australia research fellowship (#1142685) and PCD and KW by the UK Medical Research Council (MC_UU_12015/3); the latter grant and the NIHR Biomedical Research Centre in Cambridge (IS-BRC-1215–20014) supported Kate Westgate for processing the EPIC Norfolk data. The Framingham Heart Study’s data collection and analysis was funded by the National Institutes of Health, National Heart, Lung, and Blood Institute (NHLBI)-N01-HC25195; Health and Human Services (HHS) N268201500001I; R01-AG047645; R01-HL131029; and the American Heart Association (15GPSGC24800006); The Norwegian National Physical Activity Surveillance Study was supported by the Norwegian Directorate for Public Health and the Norwegian School of Sport Sciences. JT is funded by the Research Council of Norway (249932/F20); The REGARDS study was supported by a cooperative agreement U01-NS041588 and investigator-initiated grant R01-NS061846 from the National Institute of Neurological Disorders and Stroke of the National Institutes of Health. Additional funding was provided by an unrestricted research grant from The Coca-Cola Company; The Walking Away from type 2 Diabetes study was supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care East Midlands; The Women’s Health Study was funded by the National Institutes of Health (NIH) grants; CA154647, CA047988, CA182913, HL043851, HL080467, and HL099355. This research has been funded in part by the intramural research programme of the National Institute on Aging (USA).
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not required.
Ethics approval Ethical approval has been granted for all individual studies but was not required for this meta-analysis.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request. The study-specific summary data included in the meta-analyses can be obtained from the corresponding author; email@example.com.
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