Reliability and Validity of the Migraine Disability Assessment Scale among Migraine and Tension Type Headache in Iranian Patients

INTRODUCTION MIDAS is a valid and reliable short questionnaire for assessment of headache related disability. Linguistic validation of Persian MIDAS and assessment of psychometric properties between tension type headache (TTH) and migraine were the aims of this study. METHODS Patients with migraine or TTH were included. At the first visit, we administered a headache symptom questionnaire, MIDAS, and SF-36. Patients filled out MIDAS in second and third visit within three and eight weeks after base line visit. Internal consistency (Cronbach α ) and test-retest reproducibility (Spearman correlation coefficient) were used to assess reliability. Convergent validity and MIDAS capability to differentiate between chronic and episodic headaches (migraine and TTH) were also assessed. RESULTS The 267 participants had episodic migraine (EM-64%), chronic migraine (CM-13.5%), episodic TTH (ETTH-13.5%), and chronic TTH (CTTH-9). Internal consistency reliability was 0.8 for the entire sample, 0.72 for TTH, and 0.82 for migraine. Test-retest reliability for all questions between visit 1 and visit 2 varied from 0.54 to 0.71. Convergent validity was assessed using SF-36 as an external referent. Patients with episodic headaches (EM and ETTH) had significantly lower MIDAS scores than chronic headaches (CM and CTTH). CONCLUSION Persian MIDAS is a valid and reliable questionnaire for migraine and TTH that can differentiate between episodic headache and chronic headache.