Methods: Studies were identified through systematic searches of the electronic databases of Medline, Pubmed, CINAHL, Cochrane library, Airiti library. Bibliographic of retrieved articles were also searched. The following Mesh subject terms and keywords were used: hearing impairment, hearing loss, presbycusis, hearing handicap, deafness, disability, activities of daily living, older adults, elderly, aged, aging, senior. Two reviewers independently reviewed the abstract and selected studies that met the inclusion and exclusion criteria. Inclusion criteria were: (1) the study population involved individuals with age-related hearing loss/hearing impairment/presbycusis; (2) there was a predetermined definition of hearing loss/hearing impairment/presbycusis and reported disability outcome assessment; (3) cohort study. Exclusion criteria were: (1) non-English nor Chinese publication; (2) not primary research; (3) outcome not of interest. Retrieved articles were independently assessed by two raters for reporting quality using Newcastle Ottawa quality assessment scale (NOS).
Results: Ten eligible studies were identified. Only one of the 10 studies used gold-standard audiometric testing (inability to hear a tone of 40 dB or greater at 2,000 Hz frequency in the better ear is regarded as having ARHL) to evaluate hearing loss, whereas the other nine studies relied on self-report hearing problems with various questionnaires. The ARHL prevalence was from 15.7% to 28.0%. 8.6% to 57.1% participants with ARHL at baseline became disability. Compare to those without ARHL at baseline, the percentage of becoming disability is higher in participants with ARHL. The odds of disability were 0.80-7.93 times greater among older adults with hearing loss than older adults with normal hearing. However, most studies reveals that ARHL was not associated with increased odds of disability among participants with ARHL at baseline, after adjusting the covariates.
Conclusion: In the published literature, ARHL was not associated with a significantly increased odds of disability in older adults. However, HL is a gradual condition, and the limit between normal and not normal must be defined along a continuous scale.