Psychiatric diagnoses in patients previously overdiagnosed with bipolar disorder

In a previous article from the Rhode Island Methods to Improve Diagnostic Assessment and Services (MIDAS) project, we reported that bipolar disorder is often overdiagnosed in psychiatric outpatients. An important question not examined in that article was what diagnoses were given to the patients who had been overdiagnosed with bipolar disorder. In the present report from the MIDAS project, we examined whether there was a particular diagnostic profile associated with bipolar disorder overdiagnosis.

Eighty-two psychiatric outpatients reported having been previously diagnosed with bipolar disorder that was not confirmed when they were interviewed with the Structured Clinical Interview for DSM-IV (SCID). Psychiatric diagnoses were compared in these 82 patients and in 528 patients who were not previously diagnosed with bipolar disorder. Patients were interviewed by a highly trained diagnostic rater who administered a modified version of the SCID for DSM-IV Axis I disorders and the Structured Interview for DSM-IV Personality for DSM-IV Axis II disorders. This study was conducted from May 2001 to March 2005.

The most frequent lifetime diagnosis in the 82 patients previously diagnosed with bipolar disorder was major depressive disorder (82.9%, n = 68). The patients overdiagnosed with bipolar disorder were significantly more likely to be diagnosed with borderline personality disorder compared to patients who were not diagnosed with bipolar disorder (24.4% vs 6.1%; P < .001). A previous diagnosis of bipolar disorder was also associated with significantly higher lifetime rates of major depressive disorder (P < .01), posttraumatic stress disorder (P < .05), impulse control disorders (P < .05), and eating disorders (P < .05), although only the association with impulse control disorders remained significant after controlling for the presence of borderline personality disorder.

Psychiatric outpatients overdiagnosed with bipolar disorder were characterized by more Axis I and Axis II diagnostic comorbidity in general, and borderline personality disorder in particular.