Objectives To determine the impact of sitting and television viewing on life expectancy in the USA.
Design Prevalence-based cause-deleted life table analysis.
Setting Summary RRs of all-cause mortality associated with sitting and television viewing were obtained from a meta-analysis of available prospective cohort studies. Prevalences of sitting and television viewing were obtained from the US National Health and Nutrition Examination Survey.
Primary outcome measure Life expectancy at birth.
Results The estimated gains in life expectancy in the US population were 2.00 years for reducing excessive sitting to <3 h/day and a gain of 1.38 years from reducing excessive television viewing to <2 h/day. The lower and upper limits from a sensitivity analysis that involved simultaneously varying the estimates of RR (using the upper and lower bounds of the 95% CI) and the prevalence of television viewing (±20%) were 1.39 and 2.69 years for sitting and 0.48 and 2.51 years for television viewing, respectively.
Conclusion Reducing sedentary behaviours such as sitting and television viewing may have the potential to increase life expectancy in the USA.
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To cite: Katzmarzyk PT, Lee I-M. Sedentary behaviour and life expectancy in the USA: a cause-deleted life table analysis. BMJ Open 2012;2:e000828. doi:10.1136/bmjopen-2012-000828
Contributors Both authors were responsible for study conception and design. PTK was responsible for data analysis. Both authors drafted and critically revised the manuscript and approved the final version to be published. PTK is the guarantor for the study.
Funding This research received no specific grant from any funding agency in the public, commercial or non-profit sectors.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement There are no additional data available.
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