Cochlear implant comparative outcomes in Spain and Australia using the international classification of functioning, disability, and health (ICF) framework

To compare cochlear implant (CI) outcomes between cohorts in Australia and Spain using speech perception and patient-reported benefit, and to evaluate the potential utility of the International Classification of Functioning, Disability and Health (ICF) framework for cross-centre functional classification.

This retrospective cross-sectional study included 508 adult CI recipients (Australia n=266; Spain n=242) implanted between 2001 and 2022. Centre-specific speech perception scores were mapped to ICF speech discrimination (b2304) qualifiers rather than directly compared as raw scores. Patient-reported benefit was assessed with the Glasgow Benefit Inventory (GBI). Centre-stratified correlations examined associations between speech perception and GBI. Between-centre GBI differences were evaluated before and after adjustment for age at implantation, sex, implant model, electrode array and, in a sensitivity model, implantation year.

ICF-classified functional hearing outcomes did not differ significantly between centres (χ²=2.28, df=4, p=0.685). Complete GBI data were available for 316 participants (Madrid n=202; Australia n=114). Mean total GBI scores were 34.77±23.38 in Madrid and 28.62±24.19 in Australia; the unadjusted difference was significant (t(314)=2.22, p=0.027). After adjustment for age, sex, implant model and electrode array, the centre coefficient was attenuated and no longer conventionally significant (Australia vs Madrid: B=-7.09, 95% CI -14.48 to 0.31, p=0.060). A sensitivity model replacing implant model with implantation year likewise showed no significant centre effect (B=-4.78, 95% CI -11.48 to 1.93, p=0.162). Speech perception and GBI were not significantly correlated within Madrid (r=0.146, p=0.068) or Australia (r=-0.037, p=0.737).

Mapping language-specific speech perception measures to ICF qualifiers provided a common functional classification for cross-centre comparison, but should not be interpreted as establishing psychometric equivalence between the underlying tests. The unadjusted between-centre difference in patient-reported benefit was attenuated after adjustment for baseline and device-related differences, suggesting that centre-level GBI differences should be interpreted cautiously. Functional hearing and patient-reported benefit remained complementary dimensions of CI outcome.