Table A5:
Risk of Biasa Among Nonrandomized Trials, Bilateral Cochlear Implantation in Adults (ROBINS-I Tool)
| Pre-intervention | At Intervention | Post-intervention | |||||
|---|---|---|---|---|---|---|---|
| Author, Year | Confounding | Study Participant Selection | Classification of Interventions | Deviations From Intended Intervention | Missing Data | Measurement of Outcomes | Selection of Reported Results |
| Harkonen et al, 201565 | Seriousb | Moderatec,d | Low | Low | Low | Moderatee,f | Seriousf |
| Litovsky et al, 200666 | Seriousb | Moderatec,d | Low | Low | Low | Moderatee,g | Low |
| Mosnier et al, 200967 | Seriousb | Moderatec,d | Low | Low | Moderateh | Moderateg | Low |
| Olze et al, 201268 | Seriousb | Lowd | Low | Low | Low | Moderatee,g | Low |
| Ramsden et al, 200569 | Seriousb | Lowd | Low | Low | Low | Moderateg | Low |
| Reeder et al, 201470 | Seriousb | Moderatec,d | Low | Low | Low | Moderatee | Low |
| van Zon et al, 201671 | Moderatei | Low | Low | Low | Low | Moderatee | Low |
Abbreviation: ROBINS-I, Risk of Bias in Non-randomized Studies—of Interventions.
Possible risk of bias levels: low, moderate, serious, critical, and no information.
There were potential differences in patient characteristics at baseline (e.g., age at first and second cochlear implantation, degree and duration of hearing loss, duration of unilateral and bilateral auditory deprivation, history of prior hearing aid experience).
No description of inclusion or exclusion criteria.
In studies in which patients acted as their own controls, those who underwent bilateral cochlear implantation were asked to deactivate one implant to assess the difference between unilateral and bilateral hearing. This did not represent true unilateral hearing, because implantation may cause insertion damage to the cochlea, deteriorating residual hearing. Deactivating one cochlear implant for patients with bilateral cochlear implants would not reflect day-to-day listening conditions.
The self-reported nature of the questionnaires for tinnitus, subjective benefits of hearing, and quality of life increased the potential for bias in favour of bilateral cochlear implantation.
Generic questionnaires were not sensitive to changes in hearing status, and may have underestimated the gains in quality of life from bilateral cochlear implantation.
Test materials for speech perception in quiet were presented at above 60 dB (average conversational level in quiet).7
Number of patients for speech perception in noise at +5 and +10 signal-to-noise ratio dB were lower than +15 signal-to-noise ratio dB.
Cohort analysis of a randomized, controlled trial with balanced patient characteristics; however, information on prior hearing aid use—a potential confounder—was not available.