Evidence indicates that treatment for cystic fibrosis (CF) often includes antimicrobial therapy with such agents as aminoglycosides; unfortunately, research suggests such therapy can lead to ototoxicity. “Hearing loss is an under-recognized problem among individuals with CF and can cause significant effects on quality of life,” explains Anand Shah, MD, PhD. “Audiology units are rarely co-located with respiratory centers, requiring further outpatient visits to identify ototoxicity and greater expense for patients.” To decrease inconvenience and patient expenses, Dr. Shah and colleagues sought to test the performance of a tablet-based audiology system that could be administered by non-audiologists, as well as a Web-based test that could be completed at home.
Assessing Ototoxicity Tests
For a study published in Thorax, adults with CF completed a Web-based hearing test on their personal computer with standard earphones or headphones, testing 0.5, 1, and 4 kHz. Additionally, participants completed the tablet-based test (Shoebox MD) with a non-audiologist research fellow using calibrated RadioEar DD450 circumaural headphones, testing 0.25, 0.5, 1, 2, 4, 6, 8, 10, and 12.5 kHz. Before completing the tablet test, an otoscopy was performed to ensure clear ear canals and a visible tympanic membrane. At an audiology clinic, participants were tested on a pure-tone air conduction audiometry at 0.25, 0.5, 1, 2, 4, 6, 8, 10, 12.5 kHz, as well as on pure-tone bone conduction audiometry from 0.5 to 4 kHz. “We wanted to test the tablet-based audiology system against the gold-standard audiology, to determine whether it could accurately screen for hearing loss,” adds Dr. Shah. Validated questionnaires were also completed by participants to better understand the impact of hearing loss on quality of life and everyday tasks.
The tablet-based test accurately screened for hearing loss with 93% sensitivity and a 94% negative predictive value. While the Web-based test had high specificity, it only had 14% sensitivity and 58% negative predictive value. Questionnaires as a whole also had poor sensitivity (12%) and a 55% negative predictive value. “Early ototoxicity occurs at high frequencies, which are often not noticed by the patient,” explains Dr. Shah. “Our Web-based testing didn’t test extended high frequencies, which explains the poor sensitivity.” Significant impact on quality of life was found in 8% of participants.
“Like previous studies, we found 48% of adult patients with CF had detectable hearing loss at any frequency, with age and intravenous antibiotic use as significant risk factors,” notes Dr. Shah. Evidence confirms previous recommendations for routine hearing evaluations at high frequencies (>8 kHz). Age is a known risk factor for hearing loss and, within this study cohort, also likely represents cumulative antimicrobial therapy.
Future of Ototoxicity Testing
“We propose an ototoxicity monitoring program that can be translated to any outpatient-based setting with individuals at high risk of ototoxicity (Figure),” emphasizes Dr. Shah. Annual screening including vestibular and tinnitus questionnaires could identify patients with unidentified hearing loss. “Further research is still required to validate the use of tablet audiology-based longitudinal monitoring,” Dr. Shah adds. “Hopefully, further study will enable cost-effective ototoxicity monitoring and identification at an early stage when alternative therapies can be considered before irreversible hearing loss occurs.”
Dr. Shah hopes pulmonologists can use the study findings to put a local ototoxicity monitoring program in place liaising with their local audiology team. “The study has strengthened collaboration between our departments, and unfortunately, there are still very few pulmonology centers that have a screening protocol implemented,” he says. “There is also a general drive to facilitate remote monitoring, and as hardware costs become more affordable, there is a real scope to enable accurate, effective, and affordable home-based monitoring using smartphone application-based testing.”