Objective: This study was designed to assess the test-retest reliability, internal consistency, and validity of a Japanese translation of the Migraine Disability Assessment (MIDAS) Questionnaire in a sample of Japanese patients with headache.
Background: Previous studies have demonstrated that the English-language version of the MIDAS Questionnaire is a reliable and valid instrument for the assessment of migraine-related disability. Any translations of the MIDAS Questionnaire must also be assessed for reliability and validity.
Methods: Study participants were recruited from the patient population attending either the Neurology Department of Kitasato University or an affiliated clinic. Participants were eligible for study entry if they had 6 or more primary headaches per year. For reliability testing, participants completed the MIDAS Questionnaire on 2 occasions, exactly 2 weeks apart. To assess validity, patients were also invited to participate in a 90-day daily diary study. Composite measures from the 90-day diaries were compared to equivalent MIDAS measures (ie, 5 questions on headache-related disability and 1 question each on average pain intensity and headache frequency in the last 3 months) and to the total MIDAS score obtained from a third MIDAS Questionnaire completed at the end of this 90-day period.
Results: One hundred one patients between the ages of 21 and 77 years were recruited (81 women and 20 men). Ninety-nine patients (80 women and 19 men) participated in the diary study. At baseline, 46.5% of patients were MIDAS grade I or II (minimal, mild, or infrequent disability), 22.2% were MIDAS grade III (moderate disability), and 31.3% were MIDAS grade IV (severe disability). Test-retest Spearman correlations for the 5 disability questions and the questions on average pain intensity and headache frequency ranged from 0.59 to 0.80 (P<.0001). The test-retest Spearman correlation coefficient for the total MIDAS score was 0.83 (P<.0001). The degree to which individual MIDAS questions correlated with the diary-based measures ranged from 0.36 to 0.88. The correlation between the total MIDAS score and the equivalent diary-based measure was 0.66. In general, the mean and median values for the MIDAS items and total MIDAS score were similar to the means and medians for the diary-based measures. However, the mean MIDAS scores for the number of days on which headache was experienced and the number of missed workdays were significantly different compared to the diary-based estimates for these items (P<.05). In addition, the mean MIDAS score for the number of days of missed housework was significantly higher than the corresponding diary-based estimate (P<.01).
Conclusions: The results from this study show that the Japanese translation of the MIDAS Questionnaire is comparable with the English-language version in terms of reliability and validity.