Trajectory stability and factors affecting trajectories over time of the longitudinal age-related change in physical performance among older people.

This study used community-based cohort data to explore the trajectory stability (tracking coefficient or stability coefficient) and its influencing factors on the longitudinal age-related change in physical performance among older populations. An integrated statistical method with generalized estimating equations was applied to study trajectory stability. The study particularly demonstrated a mixed representation regarding the significant trajectories of intact and reduced physical performance over time. It is important to note that the trajectory stability of reduced physical performance was higher in females (odds ratio [OR] = 7.76; 95% confidence interval [CI]: 5.04-11.93) than in males (OR = 5.65; 95% CI: 4.09-7.79). However, for intact physical performance, the coefficient was 3.52 (95% CI: 2.76-4.48) in males and 2.55 (95% CI: 1.91-3.41) in females. There are further gender differences based on the influence of demographic, psychological, lifestyle, and biological variables in relation to the trajectories of physical performance. The authors conclude that an understanding of trajectory stability, as well as the factors affecting these trajectories in physical performance, is essential to the development of prevention programs tailored to maintaining functional ability or preventing the loss of physical function among older people.