Translating clinical research to clinical reality

Every day we hear and see references to research − These may be in commercials or conversation, some instances may state that “Research has taught us X or Y” or “In a research study, outcome A or B was observed”.

In audiologic clinical practice, we think about research findings as insights that guide clinical decision making and development of treatment plans. However, it’s not too often that we consider how research evolves from the simplest of questions to a treatment that is used as part of best clinical practice.

It takes years for an early research concept to develop and reach the level of understanding required for routine clinical application.

Translating research to clinical practice

Research studies are commonly regarded as having three stages of progression, basic, clinical, and translational, with each stage taking a concept from the earliest stages to later ones that are progressively closer to clinical implementation and practice. The earliest stage of research is referred to as basic research. In this case, the word basic doesn’t necessarily mean simple, rather it describes a fundamental purpose of the research as establishing a base of knowledge for future work.

In audiology and hearing science much of our basic research is done with animals, humans, and computer or laboratory simulations. Otoacoustic emissions (OAEs) are an excellent example of a biologic phenomenon that is deeply rooted in basic research.¹ More than 40 years ago, applied research in OAEs began by characterizing the emissions and understanding their physiologic sources.

The next stage is clinical research, during which we develop an understanding of human subject and clinical applications. In the example of OAEs, understanding influence of hearing loss on the OAE amplitude paved the way to future development of diagnostic tests.

Finally, translational research teaches us how new technologies, therapies, and diagnostics can be implemented in clinical setting with acceptable efficacy and efficiency. For instance, the most accurate diagnostic test may require hours of testing that is not realistic for routine clinical application.

Again, OAEs have passed through this translational stage to provide us with valuable clinical tools that are acceptable for daily use and even screening purposes, which requires an even greater depth of translational understanding to balance time and accuracy of the screening measurements.

Translating research to technology

In the development of hearing instrument technology, we see a similar progression of research. When future algorithms or hearing devices are conceptualized, the first research on a new technology uses engineering simulations that demonstrate the feasibility of a technology.

These simulations are similar to writing a standalone computer program that runs a sound progressing algorithm independent of a hearing aid or cochlear implant sound processor. The computer implementation allows for the earliest stages of research to be completed with headphones, before the time-consuming process of implementing an algorithm on the hearing instrument.

When the earliest versions of a signal processing algorithm show feasibility for human subject testing, the work will progress to clinical research and the first clinical studies with human subjects. These clinical studies provide confirmation of clinical feasibility before implementation on a hearing device.

Following confirmation of clinical feasibility, implementation on a hearing instrument will be done, which enables progress to the next translational steps and the assessment of clinical readiness.

Example of translational work

An interesting case study of this technological progression is frequency lowering, which is a common technology in today’s hearing aids. The earliest publications on frequency lowering date back to the 1950’s, demonstrating concept feasibility.

Between the 1970s and early 2000s frequency lowering had some presence in commercial hearing aids but was uncommon and the documented outcomes were inconsistent. The advancement of digital signal processing in the 2000s enabled new implementations of frequency lowering and we can look back on a wave of publications that described the clinical research on these findings in adults² and children³ as well as translational work that provided clear clinical guidance for the prescription⁴ of frequency lowering.

Research on future hearing technologies may not always follow the path outlined above. It is fundamentally exploration of something unknown, requiring flexibility in thinking an openness to innovation. Studies may not begin in a laboratory with clear progression through the clinical and translational stages, but we can find elements of these concepts in all clinical work we do today and most certainly in the emerging applications that we will use tomorrow.

For interesting reading on the evolution of research in frequency lowering, below is a link to a 10-year retrospective interview on the topic, guided by Drs Gus Mueller and Joshua Alexander in 2016 – Link

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References

1. Kemp, D. T. (1978). Stimulated acoustic emissions from within the human auditory system. The Journal of the Acoustical Society of America, 64(5), 1386-1391.
2. Ellis, R. J., & Munro, K. J. (2015). Benefit from, and acclimatization to, frequency compression hearing aids in experienced adult hearing-aid users. International journal of audiology, 54(1), 37-47.
3. McCreery, R. W., Alexander, J., Brennan, M. A., Hoover, B., Kopun, J., & Stelmachowicz, P. G. (2014). The influence of audibility on speech recognition with nonlinear frequency compression for children and adults with hearing loss. Ear and hearing, 35(4), 440–447. https://doi.org/10.1097/AUD.0000000000000027
4. Glista, D., & Scollie, S. (2018). The Use of Frequency Lowering Technology in the Treatment of Severe-to-Profound Hearing Loss: A Review of the Literature and Candidacy Considerations for Clinical Application. Seminars in hearing, 39(4), 377–389. https://doi.org/10.1055/s-0038-1670700