Establishing Responder Definitions for Short-form Headache Impact Test (HIT-6) Total and Item Scores in Chronic Migraine (430)

Objective: To identify responder definitions for HIT-6 total and item scores in patients with chronic migraine (CM). Background: Responder definitions represent the minimum amount of within-individual change needed to be interpreted as treatment benefit. HIT-6 total score responder thresholds have been defined in several headache populations; item-level thresholds have not been examined. Design/Methods: A literature search identified quantitative research of HIT-6 responder definitions. Data from PROMISE-2 (NCT02974153; n=1024) were used to conduct new responder definition analyses for HIT-6 total and item scores in CM. Distribution-based and anchor-based (patient global impression of change; ≥75% reduction in migraine frequency; EQ-5D-5L visual analog scale) methods were used to identify possible responder definition values. Candidate values from the literature (total score) and PROMISE-2 (total and item scores) were plotted against cumulative distribution functions of change values (baseline to Week 12) and used to triangulate to empirically supported responder definitions. Results: For the HIT-6 total score, responder definitions in the literature ranged from −2.5 to −8 points. Distribution- and anchor-based candidate values from PROMISE-2 ranged from −2.2 to −10.8 points. Triangulation resulted in a final HIT-6 total score responder definition value of ≥6 point decrease. Only anchor-based analyses were used to identify item-level candidate responder definition values, using the same anchors previously defined above. Final responder definitions for individual HIT-6 items were an improvement of ≥1 category on items 1 (pain severity), 2 (limits daily activities), and 3 (wish to lie down) and an improvement of ≥2 categories on items 4 (too tired to work), 5 (felt fed up/irritated), and 6 (limits concentration). Conclusions: In patients with CM, HIT-6 total score reduction of ≥6 points likely represents clinically meaningful change in headache impact. Item-level response is evidenced by an improvement of ≥1 category on items 1–3 or ≥2 categories on items 4–6. Disclosure: Dr. Houts has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Vector Psychometric Group, LLC.Dr. Wirth has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Vector Psychometric Group, LLC. Dr. Wirth has received personal compensation in an editorial capacity for Cephalalgia. Dr. Wirth has received compensation for serving on the Board of Directors of Vector Psychometric Group, LLC. Dr. Wirth has received royalty, license fees, or contractual rights payments from Vector Psychometric Group, LLC (VPG) develops and licenses numerous statistical software programs. I am an owner of VPG.. Dr. Wirth has received research support from As an employee of Vector Psychometric Group, LLC (VPG) all of my research is supported by a commercial entity (VPG)..Dr. McGinley has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Vector Psychometric Group, LLC. Dr. McGinley has received personal compensation in an editorial capacity for Cephalalgia. Dr. McGinley has received research support from Research support through the Amgen Inc. Competitive Grant Program in Migraine Research and the National Headache Foundation.Dr. Lipton has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Teva Pharmaceuticals. Dr. Lipton has received compensation for serving on the Board of Directors of eNeura and Biohaven. Dr. Lipton holds stock and/or stock options in Biohaven which sponsored research in which Dr. Lipton was involved as an investigator. Dr. Lipton holds stock and/or stock options in Biohaven. Dr. Lipton has received research support from Migraine Research Foundation the National Headache Foundation and Amgen.Dr. Hirman has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Alder BioPharmaceuticals, Inc. Dr. Cady has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Full time employee at Alder BioPharmaceuticals Inc..