- Design
- Retrospective longitudinal cohort study at a tertiary academic centre
- Population
- 360 adult cochlear implant recipients implanted 2018-2024, classified by contralateral pure-tone average into SSD (n=81), AHL (n=41) and BSHL (n=238)
- Primary outcome
- Daily device utilisation by datalogging and CNC word recognition at 1, 3, 6 and 12 months after activation
- Effect
- Full-time use (≥8 h/day) in 50% of SSD versus 82% of BSHL (P<.001); SSD the sole independent predictor of limited use, OR 4.38 (95% CI 2.03-9.48)
Cochlear implant counselling is largely uniform: expect a period of adjustment, wear the processor all waking hours, and performance will come. This retrospective longitudinal cohort of 360 adults implanted at a tertiary centre between 2018 and 2024 shows that it should not be.
Patients were classified by contralateral pure-tone average into single-sided deafness (≤30 dB HL, n=81), asymmetric hearing loss (>30-50 dB HL, n=41) and bilateral non-serviceable hearing loss (>50 dB HL, n=238), with device use taken from processor datalogging and CNC word recognition measured at 1, 3, 6 and 12 months after activation.
Single-sided deafness recipients used the device less than the bilateral group through six months, converging by twelve. Full-time use — eight hours a day or more — was reached by 50% of the single-sided group against 82% of the bilateral group (P<.001), and single-sided deafness was the only independent predictor of limited use (OR 4.38, 95% CI 2.03-9.48, P<.001). Their CNC scores stayed lower through the first year and did not cross the 50% responder threshold at twelve months.
The finding with the most practical bite is the last one. One-month performance strongly predicted twelve-month outcome in the asymmetric and bilateral groups but not in single-sided deafness — so the early check that reassures you about most recipients tells you nothing about this one.
- Counsel single-sided deafness recipients differently from the outset, not after the first poor result
- Datalogging is the measurement that matters here — ask for the hours, do not ask the patient
- Do not use one-month performance to reassure or to worry a single-sided recipient
- Half of these patients are below eight hours a day; plan surveillance around that, not around speech scores
- A hearing contralateral ear gives the patient a working alternative, which is exactly why the implant gets left off
Why it matters
The reassurance you normally take from a good one-month result does not apply to these patients.
Don't overread it
This is retrospective and from one centre; lower device use in single-sided deafness may reflect less need rather than worse outcome.
The statistics, in plain English
An odds ratio of 4.38 for limited use is large and the interval (2.03 to 9.48) does not come close to 1.0, so the association is solid within this cohort. What it cannot tell you is why — a patient with a good contralateral ear has less to gain from wearing the processor, so lower use may be a rational response rather than a failure of rehabilitation. The groups are also very unequal in size (81 versus 238), which makes the single-sided estimates less precise.
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