Sedentary behaviour and life expectancy in the USA: a cause-deleted life table analysis

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.