Percentage of Deaths Associated With Inadequate Physical Activity in the United States

Susan A. Carlson, PhD; E. Kathleen Adams, PhD; Zhou Yang, PhD; Janet E. Fulton, PhD

Disclosures

Prev Chronic Dis. 2018;15(3):e38 

In This Article

Abstract and Introduction

Abstract

Introduction Current physical activity guidelines recommend that adults participate weekly in at least 150 minutes of moderate-intensity equivalent aerobic physical activity to achieve substantial health benefits. We used a nationally representative sample of data of US adults to estimate the percentage of deaths attributable to levels of physical activity that were inadequate to meet the aerobic guideline.

Methods Data from the 1990 to 1991 National Health Interview Survey for adults aged 25 years or older were linked with mortality data up until December 31, 2011, from the National Death Index (N = 67,762 persons and 18,796 deaths). Results from fully adjusted Cox proportional hazards models were used to estimate hazard ratios and population attributable fractions for inadequate levels of physical activity (ie, less than 150 minutes per week of moderate-intensity equivalent aerobic activity).

Results Overall, 8.3% (95% confidence interval [CI], 6.4–10.2) of deaths were attributed to inadequate levels of physical activity. The percentage of deaths attributed to inadequate levels was not significant for adults aged 25 to 39 years (−0.2%; 95% CI, −8.8% to 7.7%) but was significant for adults aged 40 to 69 years (9.9%; 95% CI, 7.2%–12.6%) and adults aged 70 years or older (7.8%; 95% CI, 4.9%–10.7%).

Conclusions A significant portion of deaths was attributed to inadequate levels of physical activity. Increasing adults' physical activity levels to meet current guidelines is likely one way to reduce the risk of premature death in the United States.

Introduction

Regular participation in physical activity reduces the risk of dying prematurely.[1] The 2008 US Department of Health and Human Services Physical Activity Guidelines for Americans recommend that adults participate in at least 150 minutes of moderate intensity-equivalent aerobic activity weekly for substantial health benefits, and for additional and more extensive health benefits adults should increase this to more than 300 minutes per week.[2] Population levels of physical activity inadequate to meet guidelines can place a burden on the US population in terms of premature mortality.

The population attributable fraction (PAF)[3] provides an estimate of the percentage of deaths that could be averted if people who do not meet the guideline were active at levels consistent with the guideline. Studies have estimated the PAF for physical inactivity by using an equation that combines estimates of risk from one source and prevalence from another source.[4–7] Combining estimates across sources can bias results if the characteristics of the 2 source populations differ, if the measure of physical activity differs across sources, or if confounding is not accounted for.[3,8] Estimating the PAF from a survival analysis conducted in a single population can help overcome these biases. No study has estimated the PAF for inadequate levels of physical activity (using criteria based on guidelines)[2] from a survival analysis of a nationally representative sample.

Evidence of the association between physical activity and mortality comes from studies focused on middle-aged adults and mainly includes adults aged 40 years or older, with few data available for adults aged 80 years or older.[1,7] Researchers who examined the influence of age on the association between physical activity and mortality suggested that the association generally gets stronger with increasing age.[9–11] However, one study with 42 years of follow-up found that the PAFs for physical inactivity were consistent across age groups, ranging from 7.3% (aged 20–44 y) to 9.1% (aged ≥65 y).[11]

Our study had 2 objectives. The first was to examine the influence that physical activity level (defined using the 2008 Physical Activity Guidelines for Americans aerobic criteria) has on mortality in a nationally representative sample of the US population and to examine this association by age group. The second was to estimate the proportion of deaths attributable to inadequate levels of physical activity in US adults.

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