Literature Review

HIT-6 may help track meaningful change in chronic migraine



A more than 6-point improvement in Headache Impact Test (HIT-6) total score and a 1-2 category improvement in item-specific scores of HIT-6 appeared to be associated with meaningful change in an individual with chronic migraine, recent research suggests.

Using data from the phase 3 PROMISE-2 study, which evaluated intravenous eptinezumab in doses of 100 mg or 300 mg, or placebo every 12 weeks in 1,072 participants for the prevention of chronic migraine, Carrie R. Houts, PhD, director of psychometrics at the Vector Psychometric Group, in Chapel Hill, N.C., and colleagues determined that their finding of 6-point improvement of HIT-6 total score was consistent with other studies. However, they pointed out that little research has been done in evaluating how item-specific scores of HIT-6 impact individuals with chronic migraine. HIT-6 item scores examine whether individuals with headaches experience severe pain, limit their daily activities, have a desire to lie down, feel too tired to do daily activities, felt “fed up or irritated” because of headaches, and feel their headaches limit concentration on work or daily activities.

“The item-specific responder definitions give clinicians and researchers the ability to evaluate and track the impact of headache on specific item-level areas of patients’ lives. These responder definitions provide practical and easily interpreted results that can be used to evaluate treatment benefits over time and to improve clinician-patients communication focus on improvements in key aspects of functioning in individuals with chronic migraine,” Dr. Houts and colleagues wrote in their study, published in the October issue of Headache.

The 6-point value and the 1-2 category improvement values in item-specific scores, they suggested, could be used as a benchmark to help other clinicians and researchers detect meaningful change in individual patients with chronic migraine. Although the user guide for HIT-6 highlights a 5-point change in the total score as clinically meaningful, the authors of the guide do not provide evidence for why the 5-point value signifies clinically meaningful change, they said.

Determining thresholds of clinically meaningful change

In their study, Dr. Houts and colleagues used distribution-based methods to gauge responder values for the HIT-6 total score, while item-specific HIT-6 analyses were measured with Patients’ Global Impression of Change (PGIC), reduction in migraine frequency through monthly migraine days (MMDs), and EuroQol 5 dimensions 5 levels visual analog scale (EQ-5D-5L VAS). The researchers also used HIT-6 values from a literature review and from analyses in PROMISE-2 to calculate “a final chronic migraine-specific responder definition value” between baseline and 12 weeks. Participants in the PROMISE-2 study were mostly women (88.2%) and white (91.0%) with a mean age of 40.5 years.

The literature search revealed responder thresholds for the HIT-6 total score in a range between a decrease of 3 points and 8 points. Within PROMISE-2, the HIT-6 total score responder threshold was found to be between –2.6 and –2.2, which the researchers rounded down to a decrease of 3 points. When taking both sets of responder thresholds into account, the researchers calculated the median responder value as –5.5, which was rounded down to a decrease in 6 points in the HIT-6 total score. “[The estimate] appears most appropriate for discriminating between individuals with chronic migraine who have experienced meaningful change over time and those who have not,” Dr. Houts and colleagues said.

For item-specific HIT-6 scores, the mean score changes were –1 points for categories involving severe pain, limiting activities, lying down, and –2 points for categories involving feeling tired, being fed up or irritated, and limiting concentration.

“Taken together, the current chronic migraine-specific results are consistent with values derived from general headache/migraine samples and suggest that a decrease of 6 points or more on the HIT-6 total score would be considered meaningful to chronic migraine patients,” Dr. Houts and colleagues said. “This would translate to approximately a 4-category change on a single item, change on 2 items of approximately 2 and 3 categories, or a 1-category change on 3 or 4 of the 6 items, depending on the initial category.”

The researchers cautioned that the values outlined in the study “should not be used to determine clinically meaningful difference between treatment groups” and that “future work, similar to that reported here, will identify a chronic migraine-specific clinically meaningful difference between treatment groups value.”


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