Mobility performance impacts mortality risk in community-dwelling healthy older adults in Japan: a prospective observational study

Background: The timed up and go (TUG) test assesses balance and mobility performance. Aim: This study aims to investigate the association between TUG time and mortality in Japanese older persons and to clarify possible moderation effects on mortality and TUG time. Methods: In all, 874 participants who were ≥ 65 years of age completed the TUG test and had their anthropometric parameters and physical functions measured. We investigated the association between all-cause mortality and TUG using a Cox regression model that included confounders, and explored the time associated with mortality using a restricted cubic spline. We also performed subgroup analyses to explore whether age, sex, and body mass index (BMI) affected the relationship between TUG time and mortality. Results: The median age and mean follow-up period were 74 and 8.5 years, respectively. Median TUG time was 7.4 s and the prevalence of mortality was 25.7%. TUG time in one second was positively associated with an increased risk of total mortality [hazard ratio (HR): 1.054 (1.016–1.093); P = 0.005] in the Cox regression model. The positive association of mortality and TUG time was present when the TUG was over 10.5 s in the restricted cubic spline curve. Older age (75 years or older) moderated the relationship between TUG time and mortality [P_interaction = 0.096]. Conclusion: This study demonstrates that TUG time is associated with all-cause mortality in Japanese older adults.