The association between physical function and proximity to death in older adults: a multilevel analysis of 4,150...

When examining whether poor physical function is a risk factor for imminent death in older adults, one challenge is the lack of a meaningful time origin, a time point on which the estimate of time-to-death is anchored. In this study, we overcame this challenge by discarding the traditional-and flawed-approach of survival analysis with "time since beginning of follow up" as the time variable, and instead used a novel analytic approach that uses time-to-death as a covariate to examine its association with physical function.

Physical function and other covariates were measured annually in the Cardiovascular Health Study on 4150 individuals followed up to their time of death. Using multilevel models, we estimated gait speed and grip strength in relation to two time axes: age and proximity to death.

As individuals approached death, both gait speed and grip strength decreased significantly. However, after adjustment for health and lifestyle covariates, there was significant variation in the level of physical function between individuals.

Although physical function was significantly associated with time-to-death, there was significant variation in level of physical function between individuals at comparable proximity to death. A better understanding of these variations is needed before measures of physical function are recommended as a clinical tool for identifying individuals at high risk of death.