Examining the relevance of gait speed resiliencies to different stressors: the ARIC Study

Different stressors may impact physical resilience differently (resiliencies). Objective metrics assessing different stressors' "relevance" on associated resiliencies are lacking. We propose an approach for defining relevance metrics and potential moderating effects of sex and mortality on gait speed resiliencies.

Among 1559 ARIC participants (age 66-80 years) with "good" gait speed (≥1 m/s), 864 (55%) maintained good gait speed at follow-up (mean 6.5 years). Gait speed resiliencies were defined using 11 intermediary stressors (stroke, cancer, depression, etc.). Each stressor's relevance was examined using Relative Ratios (RRs, 95% CI), comparing the prevalence of maintaining good gait speed among those experiencing the stressor (resilience) against the prevalence among those without the stressor, adjusting for demographics and body mass index. Mortality effects and sex differences were examined.

Stressor relevance varied from greatest (self-reported poor health: RR = 0.41, [95% CI, 0.26, 0.65], 59% reduction in maintaining good gait speed), to least influential (poor social support RR = 1.02 [0.89, 1.18]), with 6/11 stressors supported as relevant. Mortality and sex-differences were present; an intermediary fall was more relevant for women, where maintaining good speed versus dying was 76% less likely after a fall, RRWomen = 0.24 (0.12, 0.50), compared to men, RRMen = 0.75 (0.39, 1.44), yielding a 67% lower chance of women having good speed versus dying after a fall than men, relevance RR-ratio = (RRWomen/RRMen) = 0.33 (0.12, 0.86).

Studies of physical resilience should use objective metrics to examine the relevance/importance of different combinations of stressors and functional outcomes when defining physical resiliencies. The relevance of gait speed resiliencies can vary by stressors, mortality inclusion in resiliencies, and sex.