- Design
- retrospective multicentre cohort study at five tertiary academic centres
- Population
- 68 adults with more than 10 years of unilateral severe to profound hearing loss; median duration 17 years (IQR 12-35)
- Primary outcome
- postoperative word recognition score and average daily device use
- Effect
- mean word recognition change +28.4 points (SD 31.6, P < 0.001); 54.5% gained 20 points or more; daily use 8.4 h then 7.1 h
Five tertiary centres reviewed adults implanted after more than ten years of unilateral severe to profound hearing loss — a group many programmes decline on the assumption that auditory deprivation of that length forecloses benefit. Sixty-eight patients were analysed, with a median duration of deafness of 17 years and an interquartile range running to 35.
Most benefited. Word recognition improved by a mean 28.4 percentage points (SD 31.6, P < 0.001) among those tested on the same instrument before and after. More than half (54.5%) gained at least 20 points and a third (32.7%) gained at least 50. Device use was substantial and sustained: a mean 8.4 hours daily in the first year and 7.1 hours beyond it, which matters because an implant that is not worn is the usual failure mode in this group.
The key negative finding is that duration of deafness did not predict post-implant word recognition on multivariable analysis. The variable most often used to refuse candidacy did not, in this cohort, carry the information it was being credited with. The standard deviation of 31.6 points is the counterweight: the average conceals a wide range, and some patients gained very little.
For a unit assessing candidacy, this argues for individual assessment rather than a duration cut-off, and for counselling that sets out the spread rather than the mean. In India, where single-sided deafness after mumps, meningitis or childhood infection often presents in adulthood after decades, a duration rule excludes a substantial group on evidence that does not support it — though implant cost remains the harder constraint.
- Do not use duration of deafness alone as an absolute exclusion from cochlear implant candidacy
- Assess candidacy individually, including in patients deaf on one side for more than a decade
- Counsel on the spread rather than the mean: over half gained 20 points or more, but the variation was wide
- Ask about expected daily use at assessment — sustained wear was what converted the implant into benefit here
- Record pre-operative word recognition on the same instrument you will use afterwards, so the gain is measurable
Why it matters
The rule of thumb that long deprivation forecloses benefit is what keeps these patients from being assessed at all.
Don't overread it
These patients had already been selected for implantation, so the results do not predict outcomes in everyone with long-standing single-sided deafness.
The statistics, in plain English
A mean improvement of 28.4 points with a standard deviation of 31.6 means the variation between patients is larger than the average gain — some improved enormously and some barely at all, so the mean is a poor guide to any individual. That duration of deafness was not predictive is a negative finding in 68 patients, which cannot exclude a real but modest relationship; it says the variable is not strong enough to select on, not that it is irrelevant. This was a retrospective cohort of patients who were offered implantation, so it describes outcomes among those already judged suitable.
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