Reliability, validity, and responsiveness of the Arabic version of HIT-6 questionnaire in patients with migraine indicated for preventive therapy: A multi-center study

Background: The Headache Impact Test (HIT-6) is an important patient-reported outcome measure (PROM) in migraine prevention trials.

Objectives: This study aimed to (i) assess the reliability and validity of the Arabic version of HIT-6 in Arabic-speaking patients experiencing migraine, and (ii) evaluate the responsiveness of HIT-6 following migraine preventive therapy.

Methods: In this prospective study, patients with migraine (n = 145) were requested to fill out a headache diary, the Arabic version of HIT-6, and Migraine Disability Assessment Scale (MIDAS) at two time points (baseline and 3 months after initiation of prophylactic treatment). Some respondents (n = 73) were requested to fill out HIT-6 again 1 week from the baseline for test-retest reliability. The intensity of migraine headache attacks was evaluated using the Visual Analogue Scale (VAS). An anchor-based method was used to establish the minimal important change (MIC) value and responsiveness of HIT-6.

Results: The total scores of HIT-6 were significantly correlated to a fair degree with MIDAS (r = 0.41), as well as VAS (r = 0.53), and monthly migraine days (r = 0.38) at the baseline while at the follow-up (after 3 months), the correlations were of moderate degree with MIDAS scores (r = 0.62) and monthly migraine days (r = 0.60; convergent validity). Reliability estimates of the Arabic HIT-6 were excellent (Cronbach's α = 0.91 at baseline and 0.89 at follow-up). The average measure interclass correlation coefficient (ICC) value for the test-retest reliability was 0.96 (95% confidence interval = 0.94-0.98, p < 0.001). The HIT-6 total score is sensitive to change, being significantly reduced after prophylactic treatment compared to before (effect size = 1.5, standardized response mean = 1.3). A reduction from baseline of 4.5 on HIT-6 showed the highest responsiveness to predict improvement with an area under the curve equal to 0.66, sensitivity of 80%, specificity of 45%, and significance at 0.021. Changes in the HIT-6 total score were positively correlated with changes in monthly migraine days (r = 0.40) and VAS scores (r = 0.69) but not with changes in the score of MIDAS (r = 0.07).

Conclusion: The Arabic version of HIT-6 is valid, reliable, and sensitive to detect clinical changes following migraine prophylactic treatment with a MIC of 4.5 points.