Validity and reliability of the Korean version of the Mood Disorder Questionnaire

This study aimed to elucidate the validity and reliability of the Korean version of the Mood Disorder Questionnaire (K-MDQ), which is a screening instrument developed for bipolar disorders.

This study translated the MDQ into Korean to produce the K-MDQ. The K-MDQ was applied to 126 outpatients with bipolar disorder clinically diagnosed by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition and 112 controls without a psychiatric history. The long-term test-retest reliability with a 10-month interval was investigated in 30 bipolar outpatients.

The internal consistency (Cronbach alpha) of the K-MDQ was .88. The correlations between each item and the total score ranged from 0.43 to 0.76 and were all statistically significant (P < .001). Factor analysis revealed 3 factors that explained 59.5% of the total variance. The mean total score was higher in patients (8.48) than in controls (4.51) (P < .001). A total K-MDQ score of at least 7 was chosen as the optimal cutoff, with the 2 parts of the questionnaire on symptoms clustering and functional problems being excluded, since this provided good sensitivity (0.75) and specificity (0.69). The Pearson correlation coefficient for the total test-retest score was 0.63 (P < .001), and the intraclass correlation coefficient was 0.77 (P < .001; 95% confidence interval, 0.52-0.89).

These findings demonstrated the adequate validity and reliability of the K-MDQ, suggesting that this instrument is useful for screening bipolar disorders in Korea. However, we recommend that the original criteria be modified to improve the sensitivity.