Assessing Postural Sway Among Older Adult Females with Hypertension

Purpose: Hypertension and use of antihypertensive medications have been generally suggested as risk factors for falls; however, supporting evidence remains unclear on the link between hypertension and balance. With minimal research assessing postural control using a force plate among older adults with hypertension, the purpose of this study is to evaluate the relationship between postural sway and blood pressure status and identify variables that contribute to falls.

Methods: This study is a retrospective, matched case-control analysis incorporating Quiet Stance Test data from the UNTHSC Human Movement Performance Lab for a case group of older adult females aged 55 to 94 with hypertension (n=100) and an age-matched and gender-matched normotensive control group (n=44) generated from previous studies conducted through the UNTHSC HMP Lab. The Quiet Stance Test involved participants standing barefoot with disposable foot covers, on pre-marked footprints on a force plate (Bertec, Columbus, OH and BioSway, Shirley, NY), both arms relaxed on the sides while looking at an eye-level target for three 10-second trials each in eyes open (EO) and eyes closed (EC) conditions. Twenty sway variables were analyzed using Paired Samples t-Test. Data were also stratified for age and height for One-Way ANOVA and Pearson Correlation tests. Tables were generated to compare mean differences between case and control groups in the EO and EC conditions. (UNTHSC IRB# 2013-102)

Results: Participants’ ages ranged from 55 to 90 (M=70.7, SD=9.3) and height from 1.45m to 1.78m (M=1.62, SD=0.07) in the case group. In the control group, participants’ ages ranged from 57 to 89 (M=68.8, SD=6.0) and height from 1.47m to 1.73m (M=1.62, SD=0.06). Roughly 80% of all participants identified as White. The Paired Samples t-Test comparing EC and EO conditions revealed significant mean differences (p<.001) for thirteen of twenty sway variables in the case group. Meanwhile, the control group showed no significant mean differences in any variable. The mean differences for four of twenty sway variables were significant (p<.001) for at least one of the height subgroups in the case group (EC condition), while the control group had no significant mean differences. The only variable that was found to have significant (p<.001) mean differences for at least one of the age subgroups is rotational frequency for the case group (EC condition). For the same group and condition, a significant positive correlation was found between rotational frequency and age (r=0.404, p<.001). The center of pressure’s (COP) position is dynamic. Rotational frequency is a measure of COP instability and is the mean velocity of the COP traveling over a circular path defined by the mean displacement from the center position of the COP stabilogram.

Conclusion: These findings suggest there may be differences in balance between normotensive and hypertensive older adult females related to age and height. A limitation of this study is that the sampling of convenience included hypertensive subjects that also have back pain concerns. Further studies should include male participants, create more racially diverse research cohorts, and consider comorbidities as variables that may provide insight into other influences on sway.