Association between Physical Activity, Weight-adjusted Waist Index, and All-cause Mortality in Chinese Older Adults:A National Community-Based Cohort Study

This study aims to explore interactions between physical activity and weight-adjusted waist index (WWI), as well as their effects on elderly health. Data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) for 2011–2018 included 7,034 residents aged ≥ 60 years. We utilized Cox proportional hazard models to assess the relationships between physical activity, WWI, and all-cause mortality, supplemented by subgroup analyses and interaction tests. We conducted a mediation analysis to assess how much of the effect of physical activity on survival status was mediated through WWI. The results showed that active individuals and those transitioning from inactive to active lifestyles exhibited significantly lower all-cause mortality risks, with reductions of 26% (HR = 0.74, CI: 0.65–0.83) and 9% (HR = 0.91, CI: 0.83–0.99), respectively. A positive correlation was found between WWI and all-cause mortality, with a threshold of 11.38 cm/√kg indicating an increased risk. Although no interaction between physical activity and WWI was observed (P = 0.462), mediation analysis showed that 3.06% of the effect of physical activity on survival status was mediated through WWI. The findings provide scientific evidence for developing health promotion strategies aimed at the elderly population.