Brazilian Portuguese version of the Headache Disability Inventory: Cross-cultural adaptation, validity, and reliability

Background The Headache Disability Inventory assesses the dimensions of headache disability, but it is not available in Brazilian Portuguese yet. We aimed to translate the Headache Disability Inventory into Brazilian Portuguese and analyze its measurement properties. Methods Consecutive patients with headaches diagnosed by expert neurologists as per the International Classification of Headache Disorders were included. For the cross-cultural adaptation, 30 individuals answered the translated Headache Disability Inventory version. The internal consistency was evaluated, and the structural validity was assessed through exploratory factor analysis. For the construct validity assessment, 132 individuals answered the Headache Disability Inventory-Brazil, 12-item Short Form Survey (SF-12), and Headache Impact Test (HIT-6). After 1-3 weeks, 67 individuals again answered the Headache Disability Inventory-Brazil for the reliability assessment. The Pearson's correlation test, the intraclass correlation coefficient and the standard error of measurement were analyzed. Results The pre-stage version of the questionnaire was considered as the final version. The Headache Disability Inventory-Brazil had an internal consistency of 0.84 and consisted of a functional, emotional and social participation domain (factor loads > 0.3). The internal consistency ranged from 0.81 to 0.93 for each of the three domains. For the construct validity, the Headache Disability Inventory-Brazil presented moderate correlation with the SF-12 (r = -0.70,p < 0.05) and with the HIT-6 (r = 0.67,p <= 0.05). Its test-retest reliability was considered to be excellent (intraclass correlation coefficient = 0.95) and the standard error of measurement was 2.26 points. Conclusion The Headache Disability Inventory-Brazil was successfully translated and culturally adapted to the Brazilian population. It can be used for the impact assessment of primary and secondary headaches with validity and reliability equivalent to its original version.