The World Health Organization's hearing-impairment grading system: an evaluation for unaided communication in age-related hearing loss.

This review evaluated the data from five datasets having pure-tone thresholds and functional measures of speech communication from relatively large groups of older adults to evaluate the validity of the proposed new World Health Organisation (WHO) hearing-impairment grading system, referred to here as WHO-proposed. This was a review of studies identified from the literature having both pure-tone audiometry and functional measures of speech communication from relatively large samples of older adults. Three population or population-sample datasets and two clinical datasets were identified with access provided to de-identified data for five of these six studies. As the WHO-proposed hearing-impairment grade progressed from "normal" to "severe" (insufficient data from older adults were available for the "profound" category), each step in this progression led to a significant difference in functional communication relative to the preceding step. Cohen's d effect sizes were moderate to very large between each successive step on the WHO-proposed hearing-impairment grading scale, with some exceptions for the step from "normal" to "mild/slight" grades. The WHO-proposed hearing-impairment grading system, recently developed through expert opinion and adopted by WHO, is validated here with evidence from studies of functional communication in older adults.