Article Text
Abstract
Objectives To examine whether moderate-to-vigorous physical activity (MVPA) modifies the association between sedentary time and mortality and vice versa, and estimate the joint associations of MVPA and sedentary time on mortality risk.
Methods This study involved individual participant data analysis of four prospective cohort studies (Norway, Sweden, USA, baseline: 2003–2016, 11 989 participants ≥50 years, 50.5% women) with hip-accelerometry-measured physical activity and sedentary time. Associations were examined using restricted cubic splines and fractional polynomials in Cox regressions adjusted for sex, education, body mass index, smoking, alcohol, study cohort, cardiovascular disease, cancer, and/or diabetes, accelerometry wear time and age.
Results 6.7% (n=805) died during follow-up (median 5.2 years, IQR 4.2 years). More than 12 daily sedentary hours (reference 8 hours) was associated with mortality risk only among those accumulating <22 min of MVPA per day (HR 1.38, 95% CI 1.10 to 1.74). Higher MVPA levels were associated with lower mortality risk irrespective of sedentary time, for example, HR for 10 versus 0 daily min of MVPA was 0.85 (95% CI 0.74 to 0.96) in those accumulating <10.5 daily sedentary hours and 0.65 (95% CI 0.53 to 0.79) in those accumulating ≥10.5 daily sedentary hours. Joint association analyses confirmed that higher MVPA was superior to lower sedentary time in lowering mortality risk, for example, 10 versus 0 daily min of MVPA was associated with 28–55% lower mortality risk across the sedentary time spectrum (lowest risk, 10 daily sedentary hours: HR 0.45, 95% CI 0.31 to 0.65).
Conclusions Sedentary time was associated with higher mortality risk but only in individuals accumulating less than 22 min of MVPA per day. Higher MVPA levels were associated with lower mortality risk irrespective of the amount of sedentary time.
- Epidemiology
- Public health
- Physical activity
- Sedentary Behavior
Data availability statement
Tromsø Study, HAI and NNPAS: The data underlying this article were provided by third parties (described below) under licence. Data can be shared on request to the third parties. NHANES data are available online at: https://wwwn.cdc.gov/nchs/nhanes/. Access to data: Tromsø Study upon application to the Data and Publication Committee for the Tromsø Study: https://uit.no/research/tromsostudy. HAI upon request to principal investigator Professor Anna Nordström, mail: anna.h.nordstrom@umu.se. NNPAS upon request to principal investigator Professor Sigmund Alfred Anderssen, mail: sigmundaa@nih.no.
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Data availability statement
Tromsø Study, HAI and NNPAS: The data underlying this article were provided by third parties (described below) under licence. Data can be shared on request to the third parties. NHANES data are available online at: https://wwwn.cdc.gov/nchs/nhanes/. Access to data: Tromsø Study upon application to the Data and Publication Committee for the Tromsø Study: https://uit.no/research/tromsostudy. HAI upon request to principal investigator Professor Anna Nordström, mail: anna.h.nordstrom@umu.se. NNPAS upon request to principal investigator Professor Sigmund Alfred Anderssen, mail: sigmundaa@nih.no.
Footnotes
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Contributors EHS, BM, UE and LAH designed the study. LAH, BM, JJ, AN, JSJ, and BHH contributed to acquisition and processing of raw data. EHS act as guarantor for the study. EHS processed the Tromsø Study and HAI accelerometry data, BHH processed the NNPAS accelerometry data, and JT processed the NHANES accelerometry data. EHS merged and harmonised the data. EHS and TW performed statistical analyses. TW, OL, and JT provided statistical expertise. EHS wrote the initial draft of the manuscript. All authors critically reviewed the study's results, contributed to revisions and approved the final version of the manuscript.
Funding This work was funded by High North Population studies, an internally funded research project at UiT The Arctic University of Norway to EHS and JJ (no grant number), and The Danish Diabetes Association to JT (no grant number). The remaining authors are funded through their respective positions/tenures.
Disclaimer The National Center for Health Statistics was not involved in analysing, interpreting, nor necessarily endorses any of the conclusions of the present study. The content is solely the responsibility of the authors.
Competing interests None declared.
Patient and public involvement statement The Tromsø Study advisory board includes patient and public representatives. Some participants acted as ambassadors in The Tromsø Study and HAI Study during data collection, and actively contributed to recruitment of participants. There was no patient or public involvement in the NNPAS or NHANES. There was no public involvement when designing and conducting this study.
Provenance and peer review Not commissioned; externally peer reviewed.
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