Trajectory Stability and Factors Affecting Trajectories Over Time of the Longitudinal Age-Related Change in Physical Performance Among Older People

Abstract

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.

Acknowledgments

This study is based on the data from the Longitudinal Survey of Health and Living Status of the Elderly in Taiwan, provided by the Bureau of Health Promotion, Department of Health, R.O.C. (Taiwan). The descriptions or conclusions herein do not represent the viewpoint of the Bureau.

Notes

¹Subjects aged 60–64 yrs and without limitations of Activities of Daily Living scale (ADLs) at baseline.

¹Intact physical performance: without any limitation of the Nagi Measures versus all others.

²Reduced physical performance: the highest quarter of the Nagi score distribution versus all others.

³The division was defined on the basis of the highest quarter (above 75th percentile) of their percentile distribution versus all others.

NA: not available, due to the low proportion (4.70%) of female subjects who exhibited betel-chewing behavior at baseline.

¹Intact physical performance: without any limitation of the Nagi Measures versus all others.

²Reduced physical performance: the highest quarter of the Nagi score distribution versus all others.

³The division was defined on the basis of the highest quarter (above 75th percentile) of their percentile distribution versus all others.

NA: not available, NA: not available, due to the low proportion (4.70%) of female subjects who exhibited betel-chewing behavior at baseline.

Other study covariates which were not significant to multivariate analysis included: body mass index, smoking habits, alcohol consumption and marital status.