@article {8103, title = {The association between physical function and proximity to death in older adults: a multilevel analysis of 4,150 decedents from the Cardiovascular Health Study.}, journal = {Ann Epidemiol}, volume = {35}, year = {2019}, month = {2019 Jul}, pages = {59-65.e5}, abstract = {

PURPOSE: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.

}, issn = {1873-2585}, doi = {10.1016/j.annepidem.2019.04.005}, author = {Karunananthan, Sathya and Moodie, Erica E M and Bergman, Howard and Payette, H{\'e}l{\`e}ne and Wolfson, David and Diehr, Paula H and Wolfson, Christina} } @article {8784, title = {Physical Function and Survival in Older Adults: A longitudinal study accounting for time-varying effects.}, journal = {Arch Gerontol Geriatr}, volume = {96}, year = {2021}, month = {2021 May 24}, pages = {104440}, abstract = {

PURPOSE OF THE STUDY: Variation in physical function in older adults over time raises several methodological challenges in the study of its association with survival, many of which have largely been overlooked in previous studies. The objective of this study is to examine the relationship between time-varying measures of physical function and survival in men and women aged 70 years and over, while accounting for the time-varying effects of health and lifestyle characteristics.

METHODS: 1,846 women and 1,245 men in the Cardiovascular Health Study followed annually for up to 10 years beginning at age 70-74 years were included. We estimated the effect of gait speed and grip strength on survival over the subsequent year, using age as the timescale.

RESULTS: A 0.1m/s higher gait speed was associated with a 12\% decrease in the likelihood of death in the subsequent year among women (HR 0.88, 95\% CI 0.82-0.94). There was no statistically significant effect of gait speed on survival among men (HR 0.97, 95\% CI 0.91 to 1.03), or of grip strength on survival among women (HR 0.97, 95\% CI 0.95-1.00) or men (HR 0.99, 95\% CI 0.97-1.01), over one year.

CONCLUSIONS: Upon using time-varying measures of physical function while accounting for time-varying effects of health and lifestyle characteristics, higher gait speed was associated with increased survival among the women in our study. We found no evidence of an association between gait speed and one-year survival in men, or between grip strength and one-year survival in women or men.

}, issn = {1872-6976}, doi = {10.1016/j.archger.2021.104440}, author = {Karunananthan, Sathya and Moodie, Erica E M and Bergman, Howard and Payette, H{\'e}l{\`e}ne and Diehr, Paula H and Wolfson, Christina} }