Linguistic and psychometric validation of the French version of the COSI questionnaire (Client-Oriented Scale of Improvement) assessing perceived improvement with hearing aids.

A single-center prospective study was conducted in 100 patients with hearing aids ( NCT06108609 ). They filled out the COSI and IOI-HA questionnaires (International Outcome Inventory for Hearing Aids). COSI is a free-choice questionnaire in which the respondent chooses 5 out of 16 items corresponding to the main auditory problems. Psychometric analysis followed the COSMIN guidelines. Test-retest reliability was assessed on intra-class correlation coefficient (ICC) in 36 patients. Correlations between COSI subscores and between COSI and global IOI-HA score were assessed.

Median COSI subscores were 3.8 [IQR: 3.2–4.2] for “degree of change” and 3.6 [IQR: 3.0–4.2] for “final ability”. Internal consistency was good, with Cronbach alpha 0.76 and 0.79 respectively. ICC was 0.68 (95% CI: 0.45–0.82) for “degree of change” and 0.81 (95% CI: 0.66–0.90) for “final ability”. There was a strong correlation between the 2 subscores: r = 0.73 (95% CI: 0.62–0.81); P < 0.001 There were moderate positive correlations between COSI and IOI-HA scores: r = 0.59 and r = 0.63; P < 0.001.

The French version of the COSI questionnaire showed satisfactory psychometric properties. Its reliability, internal consistency and clinical relevance are sufficient for inclusion in everyday practice for personalized evaluation of hearing aids.