Hearing Instruments for Unilateral Severe-to-Profound Sensorineural Hearing Loss in Adults: A Systematic Review and Meta-Analysis.

Most studies measured people before and after device use without a comparison group, so improvement could reflect practice, expectations, or other changes rather than the device. None of the studies reported a power calculation, so many may have been too small to detect real effects. Study quality was low-to-moderate: many did not report funding, ethical approval, or clear eligibility criteria. Randomization was mostly used to order device trials in the same person, not to assign treatment, and allocation methods were not described. When missing data were addressed, incomplete participants were excluded, which can bias results if people dropped out because the device did not help. Outcome measures and testing setups varied, especially for speech in noise and localization, so several questions could not be combined into a single estimate. Follow-up periods differed by device type, from 18 days for some rerouting studies to at least 6 months for cochlear implant studies, making direct comparisons difficult. Only two studies measured health-related quality of life, and both showed no significant benefit. Adverse events were not discussed in any study, so safety reporting was incomplete. The review found no randomized controlled trial evidence and the authors state no management recommendations can be based on the current evidence.

Do not conclude that a hearing device will improve all listening situations or restore sound location. The review found no reliable localization benefit from rerouting devices, and speech-in-noise benefit depended on where the talker and noise were; devices could worsen performance when noise came from the impaired ear.