Objective: Develop a functional rating scale for Huntington’s disease (HD) using iterative rounds of cognitive pretesting (CPT).

Background: We previously reported on focus group and Delphi panel review processes for the development of the FuRST 2.0, a patient reported outcome (PRO) for premanifest and early-manifest HD.

Method: CPT is a qualitative step in scale development methodology designed to assess the target population’s comprehension and comfort with the draft scale content. In CPT, face-to-face interviews, using think-aloud techniques, probing, and paraphrasing enable respondents to verbalize concerns with the scale. The results of the cognitive interviews provide direct input for modifications that must be retested. Multiple rounds of CPT are conducted until the respondents’ comments express general endorsement of comfort level and clarity of scale items and instructions at which point the official working document is ready for field-testing.

Results: This report summarizes two rounds of CPT for FuRST 2.0. In CPT round 1, 20 premanifest and 20 early-manifest HD gene expansion carriers (HDGECs) and 35 companions reviewed the scale and instructions, providing feedback to the cognitive interviewers. Following qualitative analysis and modifications to the scale, a second round of CPT was conducted in which the scale was reviewed by 20 premanifest and 20 early-manifest HDGECs and 11 companions. In addition, in between rounds 1 and 2, informal advice was received by a regulatory agency to modify wording to improve interpretability and instill inherent clinical meaningfulness in the response options. Changes were again made to the scale based on that advice. Following CPT round 2, qualitative analyses revealed further changes needed to enhance the readability of the scale.

Conclusion: Hearing the patient voice is vital to proper scale development and CPT is the primary methodology to ensure that a scale is capturing the data implicitly sought. CPT is an iterative process that may take several rounds but allows for refinements before a scale is field-tested in large populations. Once CPT is completed for this scale, a final validation study of the resultant official working document of the FuRST 2.0 will evaluate the clinimetric properties of the scale in a large international cohort.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cognitive-pretesting-of-the-functional-rating-scale-2-0-for-huntingtons-disease-furst-2-0-an-iterative-process/