Measuring Outcomes: Minimal Important Differences in Hearing Disorders Studies

Abstract

Studies utilising outcome measurements for hearing disorders may detect statistically significant results, but this does not imply that the actual changes are meaningful to the patient. The concept of minimal important differences (MIDs) was developed to estimate intervention benefits from the patient's perspective. MIDs are defined as the smallest difference in score in the outcome of interest that patients (or informed proxies) perceive as important. In contrast, the concept of just-meaningful differences (JMDs) was established to determine a patient's willingness to seek therapy. The purpose of this paper was to evaluate the possible implications of using MIDs to assess the outcomes of hearing disorder interventions. We conducted a review of the literature to outline the background to MIDs and the methodologies used to determine MIDs and to identify the knowledge gaps in hearing studies. We further undertook a scoping review to identify and catalogue the research evidence measuring MIDs in adults with hearing disorders. Our research identified a small number of hearing studies (n = 14) that calculated MIDs with outcome measurements. Four disorders were evaluated in these studies: tinnitus (n = 7), hearing loss (n = 4), vestibular schwannoma (n = 2) and otitis media (n = 1). Eight studies (57%) applied anchor- and distribution-based approaches, four (28%) employed an anchor-based, and one study used distribution-based. Notably, one study applied JMDs using aided recognition tests with the aim of estimating patients' subjective responses with an objective measurement to determine meaningful perceptual changes. There is a dearth of publications measuring and employing MIDs in hearing disorder studies, and it is therefore unclear when statistically significant findings are relevant to patients. Our study highlights the importance of MID measurements. Audiology researchers should therefore be encouraged to focus on the measurement of MIDs to help increase the benefits of hearing disorder interventions.