Successful COAs: It all starts with the “concept of interest” and “context of use”

Thursday, March 21, 2019

By: Rosie Love, MPH, PhD Candidate at the University of Maryland, Baltimore

On February 20, I presented the fourth webinar in the National Health Council’s series on Clinical Outcome Assessment (COA). Patient-reported outcomes are one example of a COA. The purpose of this webinar was to introduce the “Concept of Interest” and “Context of Use” when developing a COA measure.

A formal definition of the concept of interest (COI) in a regulatory context is “the aspect of an individual’s clinical, biological, physical, or functional state, or experience that the assessment is intended to capture (or reflect).” The concept of interest can be thought of simply as the “thing” that we are trying to measure in a COA. The concept of interest should reflect what patients tell us is important. For example, if patients tell us that fatigue is the most important symptom to them, fatigue would be an appropriate “concept of interest” for a new measure. We can only find out what patient-centered concepts of interest are by directly engaging patients. Often times we use focus groups or individual interviews to identify the concept of interest (you might have heard of these as concept elicitation interviews).

The “Context of Use” (COU) is another important aspect of COA measure development. It is defined formally as “a statement that fully and clearly describes the way the medical product development tool is to be used and the medical product development-related purpose of the use.” Simply put, the context of use is the situation that the COA instrument (such as a questionnaire) will be used. The context of use is very specific. It includes a detailed description of things like which patients the tool was designed for and what setting it can be used in.

The diagram here, taken from the FDA and known as the wheel and spoke diagram, is used to demonstrate the iterative process for the development of a successful COA. As demonstrated by the first “spoke” of the diagram, COUs and COIs are the starting point for the development of any COA.

Click here to learn more about these terms and view the webinar series.