Introduction: Bipolar disorders are relatively frequent but easily misdiagnosed. The Korean version of the Mood Disorder Questionnaire (K-MDQ) is a screening instrument for bipolar disorders. The aim of this study was to establish the pattern of responses to the K-MDQ for several psychiatric disorders.
Methods: The subjects for this study were 345 patients with bipolar disorders, schizophrenia, depressive disorders or anxiety disorders, as determined using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, and 96 controls from five hospitals. The subjects completed the questionnaire by themselves.
Results: The total K-MDQ score was higher in the bipolar disorder group than the other groups. Although the mean K-MDQ score differed significantly between the bipolar disorder group and the other groups, the distributions of total scores for the groups overlapped, and in particular with the schizophrenia group. The area under the receiver operating characteristics curve was relatively high for the bipolar disorder group and the other subjects, but it was less than 0.8 between the bipolar disorder group, and the schizophrenia and control groups.
Discussion: There are some distinguishing features of the K-MDQ pattern for each disorder, but their similarities were significant. This made it difficult to differentially diagnose the disorder using only the total K-MDQ score. The diagnostic power of the K-MDQ can only be improved in the clinical setting by utilizing reinforcing criteria to diagnose bipolar disorders. Clinicians should be cautious in their interpretation of the K-MDQ, and the use of additional data is essential.
Keywords: bipolar disorder; diagnostic error; differential diagnosis; psychiatric diagnosis; schizophrenia.
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