Independent and combined associations of upper and lower limb strength with all-cause mortality in community-based older adults: findings from the Chinese Longitudinal Healthy Longevity Survey.

ABSTRACT

OBJECTIVES: Life expectancy is increasing around the world, and it has been projected that China will have the largest elderly population globally by 2033. This study aimed to examine the association of upper limb strength (ULS) and lower limb strength (LLS) with all-cause mortality based on data from the Chinese Longitudinal Healthy Longevity Survey (2012-2018). STUDY DESIGN: This is a prospective cohort study. METHODS: Participants were 2442 older adults (aged 84.98 ± 11.94 years) recruited from eight regions with a high elderly population in China. Limb muscle strength was evaluated using handgrip strength and objective physical examinations. Cox proportional hazards regression was used to analyse the association of limb muscle strength with all-cause mortality. Demographic characteristics, health status and biological markers were included as confounders. RESULTS: Over a median follow-up period of 42.2 months, 993 participants died. After adjusting for all covariates, low ULS was associated with a higher mortality risk (hazard ratio [HR] = 1.51, 95% confidence interval [CI] = 1.25-1.84), and the association of low LLS with all-cause mortality was only significant for men (HR = 1.36, 95% CI = 1.04-1.79). Participants with combined low ULS and low LLS had the highest risk of mortality compared with participants with normal limb muscle strength (HR = 2.06, 95% CI = 1.61-2.63). The combined association of ULS and LLS with mortality was robust in subgroup and sensitivity analyses. CONCLUSION: Low ULS and low LLS were independently and synergistically associated with a higher all-cause mortality risk. Considering the high prevalence of limb muscle weakness among older adults in China, especially in those aged ≥80 years, limb strength could be considered as an easy-to-perform potential mortality predictor in community health care.