Individual Variability in Aided Outcomes

Researchers are trained to ask broad questions, probing underlying phenomena while assuming observations within a sample are representative of the population. Clinicians, in contrast, work with individuals. For the clinician who prescribes hearing aids, the model of two diagnostically similar patients demonstrating strikingly different aided outcomes has become part of the routine clinical narrative. When the fitting of hearing aids is accompanied by highly variable outcomes, it is difficult to understand if treatment effects are real or artifact, whether the magnitude of an individual's response is a probable or a chance observation, and ultimately, how experience gained by the clinician from one patient may be applied to other patients.

The investigation of individual differences has deep roots in the fields of psychology and education. Within audiology and hearing science, drivers of individual differences have most often been attributed to status-based factors (e.g., cognitive status, fatigue, and attention) or factors related to the individual's ability to extract and integrate auditory cues. Although the clinical manifestation of individual variability is fueled by these myriad factors, the clinician rarely has insight into these factors. Rather, he or she sees a patient whose outcomes may deviate from established norms, leaving the clinician with little established guidance in treatment selection.

Thus, clinicians turn to published guidelines for evidence-based practice. These guidelines are the synthesis of systematic review and provide recommendations that can be used to direct clinical decision making. In this regard, how should a clinician respond when a patient demonstrates outcomes that differ from the expectations set by evidence-based guidelines? By characterizing individual differences and performance ranges in aided outcomes, clinical expectations can be made that encompass more than the mean report alone.

This issue of Seminars in Hearing shares a collection of articles that will prepare readers for analysis and interpretation of individual differences that may occur during the evaluation of different hearing aid treatments or outcome measures. The consequent improved understanding of individual differences should help better customize treatment to the individual and their needs.