Bone conduction devices improve Sensorineural Deafness and QOL: JAMA
Bone conduction devices (BCDs) are an established form of treatment for conductive hearing loss or single sided sensorineural deafness (SSD). The BCDs work by converting sound energy to vibration of the skull bones, which results in a wave in the basilar membrane of the cochlea similar to that produced through air conduction of sound.
It is well known that BCDs improve hearing outcomes in patients with SSD, via the principle of rerouting sound from the affected side of the head to the contralateral normally hearing ear.
Hearing is integral to many aspects of human life and contributes to speech, cognition, communication, work, socializing, and entertainment. It therefore appears logical that an improvement in hearing should result in better QOL. Single-sided sensorineural deafness has been shown to be associated with decreased QOL compared with general population mean QOL scores.
Bone conduction devices have previously been used in patients with SSD with good audiological outcomes; therefore, one would assume that improving hearing with BCDs would result in an improvement in QOL. However, improvements in physical health do not universally result in an improvement in QOL. To interrogate this hypothesis further, Thomas Hampton and team conducted a meta-analysis of prospective interventional studies that included a QOL measure for patients with SSD treated with a unilateral BCD implantation.
Literature search of databases (Medline, Embase, Cochrane Library, and ClinicalTrials.gov) from January 1, 1978, to June 24, 2021, was performed. It was a prospective interventional study with 10 or more participants with SSD (defined as pure tone average >70 dB hearing loss in the worse hearing ear and 30 dB in the better hearing ear) who underwent unilateral BCD implantation and assessment of QOL before and after the intervention using a validated tool were eligible for inclusion. Studies on adults and children were eligible for inclusion. Patients with only conductive, mixed, or bilateral hearing loss were excluded.
The main study outcome was mean change in QOL scores at 6 months after insertion of BCDs. The 3 QOL instruments used in the studies included the Abbreviated Profile of Hearing Aid Benefit (APHAB), the Health Utilities Index–3 (HUI-3), and the Speech, Spatial and Qualities of Hearing Scale (SSQ). The APHAB and the SSQ are the hearing-related QOL measures, whereas the HUI-3 is a generic QOL measure.
A total of 486 articles were identified, and 11 studies with 203 patients met the inclusion criteria. Only adult studies met inclusion criteria. Ten of 11 studies were nonrandomized cohort studies.
The BCDs assessed were heterogeneous. There was a significant statistical and clinically meaningful improvement in the global APHAB scores (mean change, 15.50; 95% CI, 12.63-18.36; I 2 = 0) and the SSQ hearing qualities (mean change, 1.19; 95% CI, 0.46-1.92; I 2 = 78.4%), speech (mean change, 2.03; 95% CI, 1.68-2.37; I 2 = 0), and spatial hearing (mean change, 1.51; 95% CI, 0.57-2.44; I 2 = 81.1%) subscales. There was no significant change detected in the mean HUI-3 scores (mean change, 0.03; 95% CI, −0.04 to 0.10; I 2 = 0). The risk of bias was assessed to be low to moderate.
This review found that across 203 patients and 11 studies, generic QOL scores did not improve but hearing-specific QOL measures improved for patients treated with BCDs for SSD. This finding adds to current developments in understanding of the benefit of treatment for asymmetrical hearing loss and greater understanding that even a single hearing ear may still leave patients with significant morbidity.
This review suggests that the disease-specific QOL instruments were generally associated with greater sensitivity for detecting and demonstrating small changes in our patients' day to-day lives, and some specific tools are explicitly designed to measure changes in QOL over time or with treatment, but this leaves with 2 possible conclusions. Either hearing-specific instruments are overly sensitive to changes and hearing does not have the significant impact on overall QOL that study appreciated, or the generic instruments are too blunt to appreciate the genuine burden of SSD.
"This systematic review and meta-analysis found that BCDs are associated with significant improvements in hearing-related QOL as measured by APHAB and SSQ scores in adult patients, whereas no difference was found in the measures of generic QOL. An instrument derived from a core outcome set sensitive to hearing interventions of all types and indications would allow more meaningful comparisons of interventions. These findings have important implications for future trials and studies on health economic evaluation of BCDs in SSD. Finally, well-designed prospective studies of a range of devices in a pediatric population with SSD are urgently needed."