Assessing the feasibility of a randomised controlled trial examining the effect of hearing aids on cognitive decline in elderly individuals: a study protocol.

INTRODUCTION: Hearing loss is one of the leading potentially modifiable risk factors for dementia. There is growing evidence suggesting that treating hearing loss with hearing aids could be a relatively low-cost intervention in reducing cognitive decline and the risk of dementia in the long term. However, given the current constraints of the limited evidence, it is premature to draw definitive conclusions about the effect of hearing aids on cognitive functioning. More long-term randomised studies examining this effect would be recommended. Prior to embarking on large-scale lengthy randomised controlled trials (RCTs), it is imperative to determine the viability of such studies. Therefore, the purpose of the current study is to assess the feasibility of a RCT that investigates the effect of hearing aids on cognitive functioning in elderly hearing impaired individuals. METHODS AND ANALYSIS: In this randomised controlled feasibility trial, 24 individuals aged 65 years or older with mild to moderate hearing loss (≥35-<50 dB pure tone average (0.5-4 kHz) unilateral or bilateral) will be included and randomised towards a hearing aid intervention or no intervention. At baseline and at 6-month follow-up, a test battery consisting of cognitive tests and questionnaires will be administered to both groups. The primary outcome of the study is the willingness of hearing impaired individuals to be randomised for hearing amplification in a study regarding cognition. The secondary outcomes are the feasibility of the test battery and the therapy compliance of hearing aid use. ETHICS AND DISSEMINATION: This research protocol was approved by the Institutional Review Board of the University Medical Centre Utrecht (NL80594.041.22, V.3, January 2023). The trial results will be made accessible to the public in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: ISRCTN84550071.

Systematic review: Validity, reliability, and diagnostic accuracy of the electrogustometer.

Objective: What are the electrogustometer's (EGM) validity, reliability, and diagnostic accuracy in assessing taste sensation in adults compared to other taste tests? Data Sources: PubMed Medline, Elseviers's Embase, and the six databases of Cochrane Library. Methods: We conducted a systematic search on December 20, 2022, consisting of synonyms for EGM. We considered randomized controlled trials and observational studies with original data for inclusion if they included adults who underwent electrogustometry. Articles were excluded if no analysis regarding validity, reliability, or diagnostic accuracy had been performed or if these analyses could not be performed with the published data. Results: Nineteen articles discussing 18 studies were included for data extraction. The included studies carry a high risk of bias. Overall, the association between a variety of reference taste tests and EGM was moderate or weak with correlation coefficients ranging from -0.51 to 0.40 with one outlier of -0.74 found in one study correlating EGM and taste solutions. Test-retest reliability was good with reported correlation coefficients between 0.78 and 1.0. The sensitivity, specificity, PPV, and NPV of EGM in identifying abnormal taste function varied widely between the four studies on diagnostic accuracy. Conclusion: The included studies in this review lack the required standards regarding study design to draw firm conclusions about the validity, reliability, and diagnostic accuracy of the EGM. Future research is needed to assess these measurement properties. Based on the reported results, we would not recommend using the EGM as a screening test for taste disturbance in clinical practice. Level of Evidence: NA.