Clinical estimates of three physiologic capacities explain a majority of unipedal stance time

Abstract

Background: Recent prospective research indicates that unipedal stance time (UST) of < 15 s in middle/older adults increases their risk of repetitive falls within 5 to 10 years. Aim: To determine the extent that clinical measures of three physiologic capacities, peripheral afferent acuity, processing speed, and proximal frontal plane strength, are responsible for UST. Methods: UST, distal lower limb clinical vibratory sense, short latency go/no-go accuracy using ReacStick, and lateral plank time, were evaluated in a cohort (n = 172, 51% female, age 64.8 +/- 9.6 years) with diabetic neuropathy (n = 31), cirrhosis (n = 94), and no known neurologic disease (n = 47) using age, body mass index (BMI), sex, and medication number as covariates. Results: Multivariate analyses demonstrated that the three variables separately, and as a composite variable (vibration time + reaction accuracy/2 + lateral plank time), were associated with UST (adjusted R2 = 0.66 and 0.65, respectively) for the entire group, and for diabetic neuropathy, cirrhosis, and no known disease groups separately (adjusted R2 = 0.59, 0.60, and 0.68, respectively). The composite variable also classified participants into those with UST > and < 15 s (receiver operator characteristics area under the curve (AUC) = 0.92 (95% CI = 0.88, 0.96)). Discussion: These findings allow clinicians to identify specific physiologic deficits and develop targeted intervention strategies to improve UST. Conclusion: Clinical estimates of three physiologic capacities predict almost 2/3 of UST variability in middle/older people, rendering age, BMI, sex, and medication number less relevant.