Sensitivity and specificity of clinical markers for the diagnosis of bipolar II disorder

Bipolar II disorder is common in depressed outpatients, but the diagnosis may have low reliability because it is often based on history of hypomania. The aim of the present study was to test sensitivity and specificity for bipolar II diagnosis of some reported markers of bipolar II: atypical features, depressive mixed state, young age at onset, recurrences, and interpersonal rejection sensitivity. A total of 161 consecutive unipolar (n = 64) and bipolar II (n = 97) outpatients with major depressive episode (MDE) were interviewed using the Structured Clinical Interview for DSM-IV (SCID). Depressive mixed state was defined as a MDE with two or more (DMX2) or with three or more (DMX3) concurrent hypomanic symptoms. DMX3 and atypical features had the highest specificity (92.1% and 82.8%, respectively) and predictive power (0.69 and 0.64), but low sensitivity (46.3%, 45.3%). Concurrent presence of DMX3 and atypical features increased sensitivity (67.0%), reduced specificity (76.5%), and increased predictive power (0.75). Age at onset, recurrences, and interpersonal rejection sensitivity, concurrent with DMX3 and atypical features increased the predictive power only slightly. Thus: two cross-sectional features of a MDE, such as DMX3 and atypical symptoms, alone or in combination, may strongly support bipolar II diagnosis, and it appears that DMX3 is the best of the two. The low reliability of bipolar II diagnosis based on history of hypomania may be improved by two cross-sectional clinical markers. Copyright (C) 2001 by W.B. Saunders Company.