Does first episode polarity predict risk for suicide attempt in bipolar disorder?

Background: Defining bipolar disorder (BD) subtypes with increased risk of suicidal behavior may help clinical management. We tested the hypothesis that the polarity of a patient's first mood episode would be a marker for BD subtypes with differential risk for suicidality. Methods: One hundred thirteen subjects with DSM-IV defined BD were classified based on whether their first reported episode was manic/hypomanic (FM) or depressed (FD). They were compared on demographic and clinical variables. Logistic regression adjusting for potential confounds tested the association between first episode polarity and history of suicide attempt. Results: Multiple logistic regression analysis showed that FD group membership was associated with eightfold odds of a past suicide attempt, adjusting for years ill and total number of lifetime major depressive episodes. Limitations: Sample size, retrospective design, recall bias, assessment during a mood episode, and imprecise recall of hypomania. Conclusions: Polarity of patients' first reported mood episode suggested a depression-prone subtype with a greater probability of past suicide attempt. The FM group had more alcoholism and psychosis, but less likelihood of past suicide attempt. Validation of these putative subtypes requires prospective study.