Underestimating the severity of bipolar depression: a comparison of the Hamilton Depression Rating Scale items

Background: The Hamilton Depression Rating Scale (HDRS) is a clinician-rated instrument to assess the severity of depressive symptoms that does not account for the differences between bipolar (BP) and unipolar (UP) disorders. This study attempts to evaluate differences in the total scores of the HDRS, Beck Depression Inventory (BDI), and Global Assessment of Functioning (GAF) ratings of patients with bipolar II (BP-II) and UP depression. Each factor and item of the HDRS was compared between the two groups in order to identify specific symptoms. Methods: 588 patients with bipolar II disorder (n=101) and major depressive disorder (n=487) were enrolled in this study. All participants completed the BDI and individually interviewed using HDRS. Each participant was also evaluated with regard to global functioning. Results: The BP group scored lower on the total HDRS and all of the factors. The BP and UP groups did not differ in terms of BDI and GAF. With regard to the individual items of HORS, the BP group scored lower on items associated with 'Depressed mood', 'Work and interest', 'Somatic, gastro', and 'Hypochondriasis'. Limitations: There was a significant age differences between the two groups. Conclusions: The results of this study suggest that the severity of bipolar depression may be less well-recognized by the HDRS due to the different presentations of depressive symptoms. Thus, the clinician should be careful not to underestimate the sincerity of patients' reports when evaluating depression. (C) 2011 Elsevier B.V. All rights reserved.