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.