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

Background Disease and mortality burdens of unhealthy lifestyle behaviours are often reported. In contrast, the positive narrative around the burdens that an existing behaviour have averted is rarely acknowledged. We aimed to estimate the prevented fraction for the population (PFP) for premature mortality averted by physical activity on a global scale. Methods In this descriptive study, we obtained previously published data on physical activity prevalence (2001-16) and relative risks of all-cause mortality for 168 countries. We combined the data in Monte-Carlo simulations to estimate country-specific, mean PFP values, corresponding to percentage of mortality averted, and their 95% CIs. High prevented fractions indicated an increased proportion of deaths averted due to physical activity. Using mortality data for all people in a country aged 40-74 years, we estimated the number of premature deaths averted for all adults and by gender. We present the median and range of the prevented fractions globally, by WHO region, and by World Bank income classification. Findings The global median PFP was 15.0% (range 6.6-20.5), conservatively equating to 3.9 million (95% CI 2.5-5.6) premature deaths averted annually. The African region had the highest median prevented fraction (16.6% [range 12.1-20.5]) and the Americas had the lowest (13.1% [10.8-16.6]). Low-income countries tended to have higher prevented fractions (group median 17.9% [12.3-20.5]) than high-income countries (14.1% [6.6-17.8]). Globally, the median prevented fraction was higher for men (16.0% [7.8-20.7] than women (14.1% [5.0-20.4]). Interpretation Existing physical activity prevalence has contributed to averting premature mortality across all countries. PFP has utility as an advocacy tool to promote healthy lifestyle behaviours. By making the case of what has been achieved, the prevented fraction can show the value of current investment and services, which might be conducive to political support.