Hearing aid fitting outcome: clinical application and psychometric properties of a Swedish translation of the international outcome inventory for hearing aids (IOI-HA).

BACKGROUND

The International Outcome Inventory for Hearing Aids (IOI-HA) is a seven-item hearing-specific questionnaire. It was developed with the purpose of evaluating the efficacy of hearing aid rehabilitation. Few psychometric properties have been presented for a Swedish translation of the IOI-HA. Furthermore, previous studies have examined the IOI-HA in mainly sensorineural hearing losses, and we do not know how the type of hearing loss affects the outcome.

PURPOSE

To evaluate the hearing aid fitting outcome measured in a clinical setting using a Swedish translation of the International Outcome Inventory for Hearing Aids (IOI-HA), to determine the psychometric properties of the translation, and to examine how a number of demographic variables such as type of hearing loss affect the outcome.

RESEARCH DESIGN

A descriptive and correlational study in a retrospective sample.

STUDY SAMPLE

Two hundred and twenty-four (107 females and 117 males; ages 27-94 yr with an average of 66.1 yr) first-time hearing aid users.

INTERVENTION

Mostly digital hearing aids (97.8%) were fitted monaurally (60%) or binaurally (40%) between 2007 and 2009.

DATA COLLECTION AND ANALYSIS

The subjects were mailed the IOI-HA questionnaire six months after their final appointment, and the completed questionnaire was returned by mail to the clinic. The psychometric properties were evaluated and compared to previous studies using the IOI-HA. The associations between the outcome scores and a number of demographic variables (age, gender, degree of hearing loss, type of hearing loss, number of hearing aids, and type of hearing aids) were examined. Based on the pure tone audiograms, the subjects were divided into three groups; those with conductive hearing losses, sensorineural hearing losses, and mixed hearing losses. For these groups, the differences in outcome measured as IOI-HA were examined.

RESULTS

The psychometric properties of the present translation of the IOI-HA showed resemblance in many aspects to previous reports. Furthermore, the type of hearing loss seems to affect the IOI-HA outcome. Hearing loss increases with increasing age, and hearing aid use increases with increasing degree of hearing loss. Subjects with sensorineural hearing losses show significantly poorer scores on items concerning introspective aspects of the outcome in comparison to subjects with mixed hearing losses and subjects with conductive hearing losses. Monaurally fitted subjects tend to report lower scores on average, but monaural or binaural hearing aid fitting do not significantly affect the subjective outcome.

CONCLUSIONS

The psychometric properties of the present Swedish translation of the IOI-HA show resemblance in many aspects to previous reports, but the differences observed could be due to differences in the study populations. Overall, the demographic variables examined could not be used as predictors for the hearing aid fitting outcome, and more reliable predictors need to be identified.