Identifying Hidden Disability in Migraine Patients Using the Migraine Interictal Burden Scale-4.

Background Migraine is increasingly recognized as a disorder with a substantial burden, not only during attacks but also during interictal periods. However, this dimension of disability remains under-assessed in routine clinical practice, partly because clinical attention has traditionally focused on acute attack symptoms, while patients themselves may perceive interictal periods as "normal" and therefore underreport the psychosocial impact. The Migraine Interictal Burden Scale-4 (MIBS-4) provides a concise measure of this hidden burden; however, its clinical relevance in Japanese outpatient populations has not been thoroughly investigated. This study aimed to evaluate the clinical utility of the MIBS-4 and identify its predictors in Japanese patients with migraine by examining its association with ictal disability (HIT-6) and other clinical variables. Methods We conducted a cross-sectional study involving 81 patients diagnosed with migraine at the neurosurgical outpatient clinic. Interictal burden was assessed using the MIBS-4, and ictal disability was evaluated using the Headache Impact Test-6 (HIT-6). Emotional distress was measured using validated screening tools. Multiple regression analyses were performed to identify predictors of MIBS-4 scores. The independent variables entered into the regression model were migraine subtype, monthly migraine days (MMD), disease duration, sex, age, and headache-related disability (HIT-6).  Results Among 81 Japanese migraine patients, higher MIBS-4 scores were significantly associated with increased HIT-6 scores (β = 0.26, p < 0.001), indicating that greater headache-related disability contributes to an elevated interictal burden. Female sex was also associated with lower MIBS-4 scores (β = -1.49, p = 0.057), and longer disease duration showed a trend toward significance (p = 0.096). MMD, migraine subtype, and age were not significant predictors. Logistic regression revealed that higher HIT-6 scores (odds ratio (OR) = 1.33, p = 0.001) and longer disease duration (OR = 1.01, p = 0.016) were significantly associated with a clinically high interictal burden (MIBS-4 ≥5). Conclusion In this study, MIBS-4 scores were shown to be associated with HIT-6 scores and disease duration, but not with monthly migraine days. These findings support the utility of MIBS-4 in capturing interictal disability independently of attack frequency. Routine use of MIBS-4 in outpatient practice may help uncover hidden disease burden and guide preventive treatment strategies, particularly for patients with a long disease duration or elevated headache-related disability.