Reliability and Validity of the Greek Migraine Disability Assessment (MIDAS) Questionnaire

BACKGROUND The Migraine Disability Assessment (MIDAS) Questionnaire is a reliable and valid instrument for migraine-related disability. Such a tool is needed to quantify migraine-related disability in the Greek population. OBJECTIVE This validation study aims to assess the test-retest reliability, internal consistency, item discriminant and convergent validity of the Greek translation of the MIDAS. METHODS Adults diagnosed with migraine completed the MIDAS Questionnaire on two occasions 3 weeks apart to assess reliability, and completed the RAND-36 to assess validity. RESULTS Participants (n = 152) had a median MIDAS score of 24 and mostly severe disability (58% were grade IV). The test-retest reliability analysis (N = 59) revealed excellent reliability for the total score. Internal consistency was α = 0.71 for initial and α = 0.82 for retest completion. For item discriminant validity, the correlations between each question and the total score were significant, with high correlations for questions 2-5 (range 0.67 ≤ r ≤ 0.79; p < 0.01). For convergent validity, there was significant negative correlation between the total score and all RAND-36 subscales except for 'emotional wellbeing'. The negative correlation indicates that patients with a lower degree of disability according to their MIDAS score tended to have better wellbeing. Psychometric properties are comparable with those of other published validation studies of the MIDAS and the original. Findings on question 1 show that missing work/school days may be closely related with increased affect issues. CONCLUSION The Greek version of the MIDAS Questionnaire has good reliability and validity. This study allowed for cross-cultural comparability of research findings.