Sensitivity and specificity of DSM-IV atypical features for bipolar II disorder diagnosis

The aim of the study was to find the sensitivity and the specificity of DSM-IV atypical features (mood reactivity, weight gain, appetite increase, hypersomnia, leaden paralysis, interpersonal rejection sensitivity) for the diagnosis of bipolar II disorder. Consecutive 557 unipolar (54.9%) and bipolar II (45.0%) major depressive episode (MDE) outpatients were interviewed with the Structured Clinical Interview for DSM-IV and the Global Assessment of Functioning Scale. Bipolar II was diagnosed broadly, with a minimum duration of hypomania of at least some days, instead of the 4 days required by DSM-IV. MDE with atypical features was significantly more common in bipolar II patients. For the diagnosis of bipolar II disorder, MDE with atypical features, sensitivity was 0.45, and specificity was 0. 74. Among individual atypical features, hypersomnia had the best combination of sensitivity (0.35) and specificity (0.81). Combinations of two and three features did not improve sensitivity and specificity. As the diagnosis of past hypomania may not be very reliable from a patient's interview, atypical features may be an important marker of bipolar II disorder.