A current biomedical science research presented in the 2014 American Thoracic Society International Conference explored the possibility that sleep apnea is independently associated with both high and low frequency hearing loss.
The population-based study included 13,967 subjects from the Hispanic Community Health Study/Study of Latinos. Each individual underwent home-based sleep apnea tests and on-site audiometric evaluation at baseline. Among those included in the study, 9.9% was observed to have moderate sleep apnea, 8.4% had both high and low frequency hearing impairment, 19% had high frequency hearing impairment, and 1.5% had low frequency hearing impairment.
Sleep apnea was defined as complete cessation of airflow while the individual is at sleep. It was measured using the AHI or apnea-hypopnea index which indicates the severity of the said condition based on the number of apneas and hypopneas (partial cessation of airflow) per hour of sleep. The person is said to experience sleep apnea when AHI is at ≥ 15 events per hour. An individual is said to have low frequency hearing impairment when it was observed that they exhibit a mean hearing threshold at 500 Hz and 1000 Hz of greater than 25 decibels in either ear. High frequency hearing impairment on the other hand was defined as having a mean hearing threshold at 2000, 3000, 4000, 6000 and 8000 Hz in either ear of greater than 25 decibels.
Other possible causes of hearing loss were accordingly adjusted to determine the sole association of hearing impairment with sleep apnea, said lead author Amit Chopra, MD, who is currently at the Albany Medical Center in New York. These extraneous factors include previous history of hearing disorder, age, sex, background, and external noise exposure, among others.
Independently, sleep apnea was observed to be associated with a 90% increase in low frequency hearing impairment, 31% increase in high frequency hearing impairment, a 38% increase in both high and low frequency hearing loss disorders.
The study also found that individuals of Cuban and Puerto Rican descent were more commonly affected with hearing loss. Furthermore, physical attributes such as higher body mass index and self-reported snoring were also associated with increased risk of having hearing impairment.
Dr. Chopra points out that the occurrence of sleep apnea in patients places them in a greater risk to develop other comorbidities such as heart disease or diabetes. In this case, sleep apnea may apparently be also associated with hearing impairment.
The researchers, however, acknowledge that they are not able to take into consideration the treatments that the subjects might have been taking for sleep apnea during their study. However, they explained that the possibility that the subjects in this cohort study may be under treatment is quite slim.