Mortality following trajectories of physical function: The impact of socio-demographic factors and social relations

Abstract

Introduction It is important to help older adults maintain a good physical function in old age in order to ensure quality of life, independent living and longevity. To tailor future preventive interventions and rehabilitation, it is necessary to identify how different trajectories of physical function are associated with mortality and whether certain groups of older adults are more vulnerable to negative consequences of adverse trajectories of physical function in old age. The aims of this study are to investigate how trajectories of physical function among older adults are associated with mortality and whether socio-demographic factors and social relations modify the associations. Methods Questionnaire data linked with register data on 2906 older Danish adults aged 75 and 80 years at baseline were included. Physical function was measured by the validated Mobility-help scale (0–6) four times over a 4.5-year period. Trajectories of physical function were based on the baseline measure of physical function and slopes of linear regression lines between the four measures of physical function over time. Four trajectories of physical function were identified by: (1) stable full physical function, (2) full physical function followed by a decrease, (3) stable low physical function and (4) low physical function followed by a decrease. Multivariable additive hazard regression models were used to estimate the association between the four trajectories of physical function and the following 5-year mortality. Results Compared to older adults with a stable full physical function, older adults with a low physical function followed by a decrease were associated with the highest number of additional deaths per 1000-person-years (py) (118.02, 95% CI: 67.40; 168.64). Hereafter older adults who had full physical function followed by a decrease (82.49, 95% CI: 65.22; 99.76) and finally older adults who had a stable low physical function (70.20, 95% CI: 35.33; 105.06). Wald test for global interaction showed significant interactions (P-value Conclusions Trajectories of physical function that included decline were associated with the greatest mortality. The magnitudes of the associations between adverse trajectories of physical function and mortality were greater for men than women and those aged 80 years than those aged 75 years at baseline.