Adults with human immunodeficiency virus (HIV) are more likely to develop hearing loss than adults who don't have HIV, and this increased risk is independent of antiretroviral medication use and disease-related characteristics, reported a study published online first by JAMA Otolaryngology–Head & Neck Surgery (bit.ly/HIV-Hearinghttp://bit.ly/HIV-Hearing).
“To our knowledge, this is the first study to demonstrate that HIV-positive individuals have poorer hearing across the frequency range after many other factors known to affect hearing have been controlled for,” wrote lead author Peter Torre III, PhD, MS, associate professor at San Diego State University, and colleagues.
The authors’ approach was to evaluate how the inner ear is influenced by HIV and its medications.
“Because there is evidence that HIV affects the central nervous system as a whole, we wanted to know how the inner ear is involved,” Dr. Torre wrote in an email to The Hearing Journal (HJ).
In earlier research, Dr. Torre and colleagues saw no differences in distortion product otoacoustic emissions (DPOAEs) between HIV-positive and -negative people (Ear Hear 2014;35:56-62http://journals.lww.com/ear-hearing/pages/articleviewer.aspx?year=2014&issue=01000&article=00007&type=abstract), and this finding informed their interpretation of the new study.
“Together with our previously published work, this research suggests the differences in hearing sensitivity between HIV-positive and HIV-negative adults involve the inner hair cells within the cochlea or, more likely, the auditory neural system,” Dr. Torre wrote.
SIGNS OF SENSORINEURAL LOSS
The current study included 396 participants—262 men from the Baltimore–Washington, D.C., site of the Multicenter AIDS Cohort Study (MACS) and 134 women from the Women's Interagency HIV Study (WIHS) in Washington, D.C. Of the participants, 117 men and 105 women were HIV positive.
MACS is an ongoing, prospective study of the natural and treated history of HIV infection among men who have sex with men in the United States, and WIHS is a multicenter, prospective study of women with or at risk for HIV infection.
Each participant had standard clinical hearing tests, including an otoscopic examination, tympanometry, and pure-tone air- and bone-conduction testing. Pure-tone air-conduction thresholds were tested in each ear between 250 Hz and 8,000 Hz, and bone-conduction thresholds were tested between 500 Hz and 4,000 Hz.
A hearing-related questionnaire assessed participants’ self-reported hearing loss as a result of different factors, including perinatal exposure to rubella or cytomegalovirus, circumstances present at birth other than genetic or infectious disease, measles or meningitis, otitis media, ear trauma, or Ménière's disease or otosclerosis. Questions about tinnitus and noise exposure at work or during leisure activities were included, too.
After adjusting for age, sex, race, and noise exposure, high-frequency pure-tone average was 18 percent higher and low-frequency pure-tone average was 12 percent higher for the better ear in HIV-positive participants compared with HIV-negative participants.
Only three percent of participants had an air-bone gap, implying that most of the hearing loss was sensorineural.
CD4-positive and CD8-positive T-cell counts, plasma HIV RNA, history of AIDS, and total years of receipt of any class of antiretroviral therapy were not significantly associated with hearing sensitivity after adjustment for age, sex, race, and noise exposure.
The study was supported by the National Institute on Deafness and Other Communication Disorders (NIDCD) and the National Institutes of Health (NIH) through an agreement with the National Institute of Allergy and Infectious Diseases (NIAID).
WEIGHING THE PROS AND CONS
The thorough hearing exam conducted and the breadth of epidemiologic data gathered were strengths of the study, Dr. Torre said.
“These epidemiologic data include extensive data on HIV disease severity and medications, along with other data that may have confounded our results, such as noise exposure.
“A limitation actually includes the hearing examination also. We did not include a measure that specifically evaluated auditory neural function.
“We were limited on how many clinical measures we could complete. The data were obtained in busy university audiology clinics, so we couldn't use all of the clinical appointments for our research.”
One of the other major strengths of the study was the large sample size matched to a control group, said De Wet Swanepoel, PhD, professor in the Department of Speech–Language Pathology and Audiology at the University of Pretoria in South Africa.
“This within-subject design allows for direct comparisons between the experimental and control groups in terms of hearing loss,” he said in an email to HJ.
“A limitation of the study was that the exact antiretroviral therapy combinations and dosages for patients were not available, and, as a result, the respective contribution to ototoxicity could not be established.”
The study contributes a valuable perspective on both self-reported and measured auditory symptoms in patients with HIV, Dr. Swanepoel added.
“Monitoring patients with HIV for early detection of auditory and otological symptoms should be part of routine medical care in HIV/AIDS health services provision.”
UNCOVERING THE CAUSE
The mechanism responsible for the higher hearing thresholds observed in HIV-positive patients is not yet clear. Many factors possibly play a role, said Jay Buckey, MD, professor of medicine at the Geisel School of Medicine at Dartmouth and senior author of a study that indicated the presence of a central processing deficit in patients with HIV.
“There are a lot of potential things that could affect your hearing if you have HIV: could be the HIV virus itself, could be a consequence of HIV infection, could be related to the drugs—if not directly, then maybe making you more sensitive to other problems,” Dr. Buckey said.
“There could be other interactions between the HIV infection and your genetic makeup, and then, of course, there's the other factor of HIV affecting the central part of the hearing system because we know that people with HIV infection do develop other central nervous system consequences of having HIV.”
In the current study, opportunistic infections and ototoxic characteristics of certain antiretroviral therapy combinations may have contributed to the observed hearing loss, Dr. Swanepoel said.
“In addition, the proposed direct effects of the virus on the cochlea and auditory nerve might have had an additive effect. Future research must focus on establishing and quantifying the respective contributions of these contributing factors to the prevalence of hearing loss in these patients.”
Dr. Torre and Howard J. Hoffman, MA, director of the NIDCD Epidemiology and Statistics Program and coauthor of the study, hope to evaluate in later studies the circumstances driving hearing loss among HIV-positive patients.
“We would like to examine the association between HIV and speech audiometry measures,” Mr. Hoffman wrote. “Ultimately, our goal is to determine whether it is the disease itself or the medications used to treat HIV (the possibility of ototoxicity) that are the underlying cause of hearing differences between HIV-positive and HIV-negative adults.”