The Effect of Hearing Loss and Hearing Device Fitting on Fatigue in Adults: A Systematic Review

To conduct a systematic review to address two research questions: (Q1) Does hearing loss have an effect on fatigue? (Q2) Does hearing device fitting have an effect on fatigue? It was hypothesized that hearing loss would increase fatigue (H1), and hearing device fitting would reduce fatigue (H2).

Systematic searches were undertaken of five bibliographic databases: Embase, MedLine, Web of Science, Psychinfo, and the Cochrane Library. English language peer-reviewed research articles were included from inception until present. Inclusion and exclusion criteria were formulated using the Population, Intervention, Comparison, Outcomes and Study design strategy.

Initial searches for both research questions produced 1,227 unique articles, after removal of duplicates. After screening, the full text of 61 studies was checked, resulting in 12 articles with content relevant to the research questions. The reference lists of these studies were examined, and a final updated search was conducted on October 16, 2019. This resulted in a final total of 20 studies being selected for the review. For each study, the information relating to the Population, Intervention, Comparison, Outcomes and Study design criteria and the statistical outcomes relating to both questions (Q1 and Q2) were extracted. Evidence relating to Q1 was provided by 15 studies, reporting 24 findings. Evidence relating to Q2 was provided by six studies, reporting eight findings. One study provided evidence for both. Using the Grading of Recommendations Assessment, Development and Evaluation guidelines, the quality of evidence on both research questions was deemed to be "very low." It was impossible to perform a meta-analysis of the results due to a lack of homogeneity.

As the studies were too heterogeneous to support a meta-analysis, it was not possible to provide statistically significant evidence to support the hypotheses that hearing loss results in increased fatigue (H1) or that hearing device fitting results in decreased fatigue (H2). Despite this, the comparative volume of positive results and the lack of any negative findings are promising for future research (particularly in respect of Q1). There was a very small number of studies deemed eligible for the review, and there was large variability between studies in terms of population, and quantification of hearing loss and fatigue. The review highlights the need for consistency when measuring fatigue, particularly when using self-report questionnaires, where the majority of the current evidence was generated.