Use of the prevented fraction for the population to determine deaths averted by existing prevalence of physical activity: a descriptive study

Background: The disease or mortality burdens of unhealthy lifestyle behaviours are often reported. The positive side of the story, the burden that existing levels have averted, is rarely discussed. We present what we believe to be global application of the Prevented Fraction for the Population to obtain estimates of the percentage of premature mortality and number of premature deaths averted by total physical activity levels for 168 countries. Methods: We combined previously published activity prevalence data (2001-2016) and relative risks of mortality in Monte-Carlo simulations to estimate country-specific Prevented Fractions for the Population (percentage of mortality averted) and their 95% confidence intervals. Higher Prevented Fractions indicate a greater proportion of deaths averted due to physical activity. Using mortality data for 40-74 year olds, we estimated the number of premature deaths averted due to activity levels for all adults and by sex. We presented the median and range of the Prevented Fractions globally, by region, and by income classification. Results: The global median Prevented Fraction for the Population was 15.0% (range 6.6-20.5%), conservatively equating to 3.9 million (95% confidence interval: 2.5-5.6) premature deaths averted annually. The African region had the highest median (16.6%, range 12.1-20.5%), the Americas had the lowest (13.1%, range 10.8-16.6%). Low income countries tended to have higher median Prevented Fractions (17.9%, range 12.3-20.5%) than high income countries (14.1%, range 6.6-17.8%). Globally, the median Prevented Fraction was higher for men than women (16.0% (range 7.8-20.7% and 14.1% (range 5.0-20.4%), respectively). Interpretation: Existing physical activity levels have contributed to averting premature mortality across all countries. The Prevented Fraction for the Population has utility as an advocacy tool to promote healthy lifestyle behaviours as, by making the case of what has been achieved, it could demonstrate the value of current investment and services. This may be more conducive to political support.
TS, SJS, and SB are funded by the UK Medical Research Council (MC_UU_12015/1 and MC_UU_12015/3). DD is funded by a Future Leader Fellowship by Heart Foundation Australia (No. 101234). At the time of this work, MT was a member of the Centre for Diet and Activity Research (MR/K023187/1), a UKCRC Public Health Research Centre of Excellence. Funding from the British Heart Foundation, Cancer Research UK, Economic and Social Research Council, Medical Research Council, National Institute for Health Research (NIHR), and Wellcome Trust, under the auspices of the UKClinical Research Collaboration, is gratefully acknowledged. MT was also funded on the METAHIT project (Medical Research Council grant MR/P02663X/1).