Despite ongoing discussion regarding the 6-item Headache Impact Test’s relevance in the migraine population—for which it was not specifically developed—the test has been shown to be a useful tool in the assessment of patients with migraine.
Carrie Houts, PhD
A pair of poster presentations suggest not only that the 6-item Headache Impact Test (HIT-6) questionnaire measures important and relevant constructs of the impact of headache in patients with migraine, but that specifically, a decrease of 6 points or more appears to be the best threshold for a meaningful decrease in total score for those with chronic migraine.
The first analysis explored the content validity of the HIT-6 score in a systematic review of 12 publications including data from more than 200 patients with migraine, of which 16 were identified as having chronic migraine. It found that all 6 items correlate with notions that are of importance to patients, specifically with respect to their experience with migraine and its impact on their lives.1
Additionally, research indicated that patients understood the HIT-6 instructions, items, and response scales as intended by the instrument authors.
The second study sought to determine what alteration in HIT-6 score defined a meaningful response for those with chronic migraine, using data from systemic searches of the available literature, as well as responder definition analysis using data from the PROMISE-2 study (NCT02974153), which included a cohort of 1024 patients.2
The study data were presented at the 2019 American Headache Society (AHS) Annual Meeting, July 11-14, 2019, in Philadelphia, Pennsylvania, by Carrie Houts, PhD, director of psychometrics, Vector Psychometrics Group, and Roger Cady, MD, FAHS, vice president of neurology, Alder BioPharmaceuticals, respectively.
Houts and colleagues conducted their review of the HIT-6’s content validity by examining 1-on-1 patient interviews or patient-centered focus groups, which featured a total of 283 patients, of which 214 had migraine. They identified a number of “overarching themes” which were hit on by each HIT-6 item—severe pain during headache, the limitations in daily activities, the need to lie down during headaches, tiredness due to headaches, irritation from headaches, and difficulty concentrating during headaches.
“Direct quotes from migraine patients further demonstrated that the HIT-6 assesses features, symptoms, and impacts of migraine that meaningfully affect the lives of patients with migraine,” Houts and co-investigators wrote. “As the HIT-6 was not specifically developed to assess outcomes in patients with migraine, its relevance in this population has been an ongoing topic of discussion.”
Therefore, they wrote, their objective was to identify qualitative evidence of its usefulness in those with migraine.
Meanwhile, Cady and colleagues used anchor-based calculations which used patient global impression of change, ≥75% reduction in migraine frequency, and EQ-5D-5L visual analog scale to define groups. They also used distribution-based calculations included half of baseline HIT-6 standard deviation (2.57) and the baseline standard error of measurement (2.18). From there, the resulting values were plotted against the cumulative distribution function of change values.
Their evaluation included data from 5 studies other than PROMISE-2: Castien et al. (2002), which included 186 patients with chronic tension-type headache; Coyteaux et al. (2006), which included 71 patients with chronic daily headache; Rendas-Baum et al. (2014), which included 1384 patients with chronic migraine; Smelt et al. (2014), which included 368 patients with migraine; and Bayliss & Batenhorst (2002), in which the population was unspecified.
In total, they found that HIT-6 score responder definitions in the completed literature varied from −2.5 points to −8 points, while distribution- and anchor-based candidate thresholds collected from the PROMISE-2 data ranged from −2.2 to −10.8. When the group completed the triangulation, it resulted in an estimate of −6.
“Taking [less than] 5 minutes to complete, the HIT-6 questionnaire is a valuable and easy-to-administer patient-reported outcome that can be easily incorporated into clinical trial evaluations and clinical practice,” Cady and colleagues concluded.
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1. Houts C. Content validity of the HIT-6 in migraine patients: results of a systematic literature review. Presented at: 2019 American Headache Society Annual Meeting; July 11-14, 2019; Philadelphia, PA. Poster 213LB.
2. Cady R. Chronic migraine: Establishing a responder definition for the HIT-6 total score. Presented at: 2019 American Headache Society Annual Meeting; July 11-14, 2019; Philadelphia, PA. 215LB.