Association of balance impairment with risk of incident cardiovascular diseases among older adults

Despite a gradual decline in cardiovascular diseases (CVD) prevalence in developed countries due to therapeutic advances and preventative efforts, CVD remains a significant burden in an aging population [1]. CVD not only causes progressive dysfunction in older adults, but also remain as the leading cause of death in this age group [2]. Evidence-based clinical practice guidelines are frequently used and generally followed by practitioners in the field of cardiovascular care [3]. Although the identification and implementation of CVD risk factors according to these guidelines has greatly benefited the general population, such recommendations may be less reliable in older adults, as clinical complexities associated with aging are more likely to confound standard precepts [4].

Along with aging, the gradual biologic changes associated with longevity are favorable to the onset of CVD and other age-related geriatric conditions such as frailty, sarcopenia, and falls [2, 5]. For older adults, mobility impairment is associated with a lower quality of life, an increased risk of institutionalization, and premature death [6]. While good mobility necessitates the ability to maintain one's balance while engaging in a variety of activities [7], aging can cause changes that lead to dysfunctional balancing, independently of illness or medication [8, 9]. Maintaining balance requires comprehensive contributions from the vestibular, visual, and proprioceptive systems [10].

Recently, a significant inverse association between balance function and CVD-related mortality risk was reported [7]. Similarly, a link between locomotor dysfunction and an increased risk of CVD has been found in the adults of mean age 66 [11]. Despite ongoing efforts to determine the influence of mobility dysfunction on the CVD risk, the presence of balance dysfunction is likely underestimated in clinical practice, and most investigations are focused on the mortality risk of CVD [6, 12]. Hence, we conducted this study to provide an evidence whether balance function increases the risk of CVD and the extent of risk elevation using the one-leg standing (OLS) test, which is an easy way to self-recognize balance function and CVD risk.

The association between OLS test and the risk of CVD was noted in this study. Participants with impaired balance function had a 1.23-fold increased CVD risk compared to participants with normal balance function after adjusting for potential confounders. Despite older adults with impaired balance function were more likely to develop both CHD and stroke, the balance function-dependent risk was stronger for stroke. These findings may pave a way for further investigation into the relationship between balance function and the risk of CVD, providing supports for effective healthcare initiatives.

In the present study, the proportions of cautious and abnormal groups were 20.3% and 11.5%, respectively, which are lower than a Swedish study of 351 women aged 69–79 years (median, 72.4 years) showed that the median OLS time was 19 s (interquartile range, 1.5–30) and 22.5 s (interquartile range, 2–30) for right-leg and left-leg standing participants with high exercise, respectively [19]. Impaired balance contributes to a wide range of negative health outcomes [20]. However, there is limited evidence regarding balance function and the onset of CVD. A recent study involving 5816 US adults aged over 40 found that those with a balance dysfunction had a 65% higher CVD mortality compared to those with normal balance function, as measured by the modified Romberg standing balance test [7]. In a Japanese cohort study with 1,085 old participants aged 65–89 years who received the OLS test, balance impairment was associated with a 91% increased risk of CVD-related death [21]. Another recent Turkish study involving 44 older adults with a mean age of 59 found that balance function was reduced in patients with chronic heart failure as measured by the Activity-Specific Balance Confidence Scale and the Mini-Balance Evaluation Systems Test [20]. The present study expands current knowledge on association of balance function with incident CVD that cautious or abnormal balance function is associated with a higher risk of CVD among older adults.

A behavior-related mechanism may explain the association between balance function and incident CVD. The prevalence of vestibular dysfunction rise sharply with aging, and this can affect the balance function of individuals [22]. People who experienced symptoms such as dizziness as a result of vestibular impairment were 12 times more likely to fall than those with normal vestibular function [22]. Falls, primarily caused by poor balance can result in long-term immobility and a sedentary lifestyle [23]. Certain sedentary behaviors have been associated with an increased risk of CVD [24, 25]. Furthermore, fear of falling causes older adults to be less active and spend more time sitting than they should, increasing their CVD risk [24]. In a biological manner, the activity of the lipoprotein lipase in the postural muscles of rats has been shown to decrease when they are forced to remain immobile [26]. Low levels of lipoprotein lipase are associated with reduced triacylglycerol uptake, lower plasma HDL cholesterol levels, and higher risk of CVD [26]. In addition, lipid abnormalities are related to an increased risk of atherosclerosis or myocardial infarction in patients with vertigo [27].

Another possible explanation is that frailty caused by balance impairment increases the risk of CVD. Despite the fact that a variety of definitions for quantifying frailty status have been proposed [21], poor physical performance is widely recognized as a hallmark of frailty. Perhaps the increased risk of CVD in frail old people is due to their susceptibility to psychological and physiological stresses [21]. Although there is limited evidence to support frailty to a risk factor for CVD incidence, it has been associated to both clinical and underlying CVD [28]. To better inform clinical practice, further investigation to clarify pathways connecting balance disorder and CVD risk is warranted.

To date, assessing the balance of older adults has not been standard practice in clinical examinations. This could be attributed to a lack of consensus on how to measure balance, as well as a lack of information linking balance test results to clinical outcomes other than falls [6]. Therefore, the findings of this study may be useful for screening individuals at risk of CVD and suggesting prevention and intervention initiatives to lower the risk of CVD [29]. However, the following limitations should be considered when interpreting this study results. First, this study is not exempt to the issue of reverse causality because of its retrospective nature. Future prospective studies would be warranted to determine the causal relationship between balance impairment and the risk of CVD. Second, the OLS test was the only parameter used to assess balance performance in this study. Although OLS has been one of the standard methods for evaluating postural stability for several decades, due to its ease of use and short test time [30, 31], additional studies based on other metrics for measuring balance function may be required to generalize our findings. Third, not all potential confounding factors, such as muscle wasting, physical fitness, and cognitive impairment could be considered for the adjusted analyses due to the unavailability of information. Lastly, our study determined the cause-specific aHR for the risk of CVD according to the OLS test results. Evaluating subdistribution hazard ratio that set non-CVD death as a competing event may be necessary to better determine the association of balance function with the risk of CVD.

Balance impairment was associated with an increased risk of incident CVD in this nationally representative cohort study of Korean older adults. As the prevalence of balance impairments rises with aging, assessing balance function in clinical and research settings may be considered to better estimate the risk of CVD. Such assessment may allow better referrals to specialists for individual-level healthcare plans.