An estimated 35% of Americans aged 40 and older have objective evidence of vestibular dysfunction, according to a recent report.
If further research bears out this finding from this study, it means that approximately 69 million adults in the United States are affected, said Dr. Yuri Agrawal and his associates in the department of otolaryngology-head and neck surgery at Johns Hopkins University School of Medicine, Baltimore.
The investigators assessed the epidemiology of vestibular dysfunction, because little has been published about the issue, even though both the incidence and prevalence of fall-induced injuries has risen significantly over the past 25 years. They used data from two 2-year cycles of data from the National Health and Nutrition Examination Survey between 2001 and 2004 to estimate the prevalence of the disorder.
A total of 5,086 NHANES subjects underwent balance testing using a modified Romberg Test of Standing Balance on Firm and Compliant Support Surfaces, which assessed their ability to stand unassisted under four test conditions. One of the conditions—standing on a foam-padded surface that obscured proprioceptive input while closing their eyes to eliminate visual input—exclusively measured vestibular function.
The overall prevalence of the disorder was 35.4%, which corresponds to 69 million Americans aged 40 and older. This prevalence increased markedly with age (from 18.5% for those in their 40s to 85% in those aged 80 and older). The prevalence did not differ significantly between men and women (34% vs. 35%).
“We found that participants with vestibular dysfunction had a significantly increased odds of hearing loss, compared with participants without vestibular dysfunction,” Dr. Agrawal and his associates said (Arch. Intern. Med. 2009;169:938–44).
This shared susceptibility “likely reflects the common anatomic location of the vestibular and hearing organs, as well as a common blood supply, making both systems potentially vulnerable to the same degenerative, ischemic, traumatic, or toxic insults,” they noted.
Similarly, there was a significant association between vestibular dysfunction and a history of dizziness and falling.
A total of 536 study subjects reported dizziness and were found to have vestibular dysfunction. These participants were 12 times more likely to report having fallen as were subjects who had no dizziness and no vestibular dysfunction.
There were many subjects who reported no dizziness but were found to have vestibular dysfunction upon testing, however. These subjects also were at significantly increased risk for falling, with an odds ratio of 6.3, the researchers said.
The prevalence of vestibular dysfunction did not differ among non-Hispanic whites (34.7%), non-Hispanic blacks (35.5%), and Mexican-Americans (34.3%). It was significantly higher, however, in study participants categorized as “other” races or ethnicities (42.4%). “Perhaps genetic factors play a role, and indeed, several genes have been implicated in the pathophysiologic mechanism of one particular vestibulopathy, Meniere disease,” the researchers wrote.
Alternatively, subjects who had higher levels of education showed a markedly lower prevalence of vestibular dysfunction than those with less education, ranging from 51% in those with less than a high school education to 29% in those with greater than a high school eductation. This striking protective effect that has been noted in previous studies. “Incomplete adjustment for risk factors such as hypertension and diabetes may explain these socioeconomic and ethnic disparities,” Dr. Agrawal and his colleagues said.
Given this high prevalence in the general population, “screening for vestibular dysfunction … could be a life-saving and cost-effective practice,” particularly in high-risk groups such as the very old, people with hearing impairment, ethnic and racial minorities, and people with less than a high-school education. Those who are identified as having the disorder may benefit from vestibular physical therapy to improve balance control and prevent falls, they added.