Missing bipolar disorder

More than 3% of patients currently being treated for unipolar depression may have unrecognised bipolar disorder, a UK study of primary care patients has reported.

Researchers approached 3117 individuals diagnosed with unipolar depression. Of those, 576 completed questionnaires. Of the 154 who were subsequently interviewed, nine had never had an episode of major depression, 116 had a history of major depressive disorder, and 29 met DSM-IV criteria for bipolar disorder.

The authors provide three estimates of undiagnosed bipolar disorder. The least conservative (21.6%) assumes that all who weren’t interviewed or didn’t return their questionnaires would have responded similarly to the interviewees.

The most conservative estimate of 3.3% assumes that any patient who did not complete the questionnaire nor was interviewed does not have bipolar disorder.

Br J Psychiatry 2011; 199:49-56. doi:10.1192/bjp.bp.110.083840