Risk factors for suicide attempts in patients with bipolar disorder misdiagnosed with major depressive disorder: results from a national survey in China

Abstract Background: Bipolar disorder (BD) is a kind of mental disorder with the greatest risk of suicide, but it is often misdiagnosed as major depressive disorder (MDD) clinically. This study aimed to analyze the sociodemographic factors and clinical characteristics associated with suicide attempts (SA) in patients with BD misdiagnosed with MDD in China. Methods: A total of 1487 MDD patients were consecutively enrolled in 13 mental health centers in China. Data on patients’ sociodemographic and clinical characteristics were collected using a standardized protocol. Of these, 306 BD patients were misdiagnosed with MDD according to the Mini International Neuropsychiatric Interview (MINI). Suicide attempters and non-attempters were classified by the suicidality module of the MINI. Multiple logistic regression analyses were performed to assess the association between the independent variables of interest and SA in BD patients misdiagnosed with MDD. Results: Of the 306 BD patients misdiagnosed with MDD, 225 (73.5%) were non-attempters and 81 (26.5%) were attempters. Compared to non-attempters, attempters were older (Z =2.2, p = 0.03) and had more admissions(χ2 =6.1, p = 0.013), more frequent depressive episodes, more atypical characteristics (e.g. increased appetite, weight gain, and more sleep time)(χ2 = 5.8, p = 0.016), more suicidal ideation (χ2 = 27.3, p < 0.001), more psychotic symptoms (χ2 = 7.4, p = 0.006) and more seasonal depressive episodes (χ2 = 5.6, p = 0.018). Multiple logistic regression analyses revealed that attempters were characterized by more suicidal ideation (OR = 5.7, 95% CI: 2.6–12.5) and frequent depressive episodes (OR = 2.4, 95% CI: 1.3–4.6). The limitations of this study include its cross-sectional design and data collection by suicide attempters’ retrospective recall. Conclusions: The findings of this study suggest that BD patients misdiagnosed with MDD are at a higher risk of suicide, and more frequent depressive episodes and suicidal ideation are risk factors for attempted suicide. Early identification of and interventions for these risk factors might reduce the risk of suicide in BD patients misdiagnosed with MDD.