Associations between upper limb flexibility and all-cause mortality in the oldest-old.

Background: Upper limb flexibility (ULF) is a simple and feasible measure of physical function in long-lived population. This study aimed to explore the association of ULF with all-cause mortality in community-dwelling oldest-old in China. Methods: A total of 21 861 older adults aged ≥80 years were enrolled from five waves of the Chinese Longitudinal Healthy Longevity Survey. The assessment of ULF at baseline involved three objective physical tasks (touching the root of the neck, touching the lower back, and raising arms vertically). All participants were followed up until 2018, during which survival information was collected. Cox proportional hazards regression model was used to analyse the association between ULF and all-cause mortality. Demographic characteristics, health behaviours, and disease history were included as covariates. Results: After 72 586.42 person years of follow-up, 18 570 people died. After adjusting for all confounding factors, both left and right ULF impairments were correlated with an increased risk of all-cause mortality, with adjusted hazard ratio (HR) of 1.06 (95% confidence interval (CI) = 1.01, 1.12) and 1.12 (95% CI = 1.05, 1.20). In the collaborative analyses, individuals exhibiting ULF impairment across both the left and right sides had the highest mortality risk with adjusted HR of 1.29 (95% CI = 1.19, 1.38). We found significant additive interaction between left and right ULF impairment on all-cause mortality (relative excess risk due to interaction = 0.10; 95% CI = 0.02, 0.18). The principal findings maintained stable across sensitivity analyses. Conclusion: Impaired ULF is associated with a higher risk of all-cause mortality among the oldest-old in China, especially when the impairment occurs on the right side. For the oldest-old, ULF may serve as a simple and effective predictor of premature death.