Risk Factors Linked to Suicidal Acts Vary in Bipolar Disorder vs Depression

Although greater suicidal risk overall was more associated with bipolar disorder, risk factors associated with suicidal acts differed between affective disorders, according to a study published in the British Journal of Psychiatry. Defining risk factors for individual types of mood disorders can enhance identification of suicidal risk and improve treatment and prognosis.

The investigators of this study sought to identify risk factors associated with suicidal behavior in adults with major mood disorders and to compare the prevalence of specific factors associated with risk in bipolar disorder vs major depressive disorder.

The study included 3284 adults diagnosed with bipolar disorder type I, bipolar disorder type II, or major depressive disorder with or without suicidal acts. Participants were assessed for suicidal behavior and associated risk factors before, during, and after intake. Their demographic and clinical characteristics were derived from semi-structured interviews and life charts, which were updated throughout the study period. Suicide rates and risk factors were compared in the overall study sample as well as among patients with bipolar disorder vs major depressive disorder using bivariate comparisons and multivariable regression modeling. Factors supported by the latter were included in receiver operating characteristic analysis to determine the sensitivity and specificity between any 2 factors.

The lifetime risk for suicidal ideation was significantly greater in patients with bipolar disorder vs major depressive disorder (29.2% vs 17.3%), as was the risk of attempted suicide (18.8% vs 4.78%) and suicide (1.73% vs 0.48%). As a proposed measure of lethality, the ratio of attempts to suicide was similar among patients with bipolar disorder vs depression (11.1 vs 10.2). Although the proportion of violent attempts or suicides was also found to be similar among patients with bipolar disorder vs depression (33.1% vs 23.9%), it was significantly greater in patients with bipolar disorder type I vs type II (38.2% vs 23.0%).

Risk factors associated with suicidal acts among all patients included a history of major affective disorder, familial bipolar disorder, or suicide; being divorced or unmarried and having fewer children; early abuse or trauma experience; unemployment or having a low socioeconomic status; younger onset with more years at risk; having >4 prior depressions; hospitalization for psychiatric illness; comorbid attention deficit hyperactivity disorder; being of more dysthymic or cyclothymic temperament; misuse of drugs, alcohol, or smoking; less antidepressant monotherapy, and greater use of mood stabilizers or antipsychotics. Logistic regression modeling identified 5 independent risk factors: hospitalization, more depression at intake, bipolar diagnosis, disease onset ≤25 years, and mixed features. Factors that were more strongly associated with bipolar disorder vs depression included percentage of time depressed or ill, alcohol misuse, >4 pre-intake depressions, more dysthymic or cyclothymic temperament, and prior abuse and/or trauma. Except for attention deficit hyperactivity disorder and years at risk, which were similar in both bipolar disorder and depression, the remaining factors were more strongly associated with major depressive disorder.

Limitations to the study were including factors derived from patient histories, which may be vulnerable to errors, and observations made in a mood disorder center, which may be subject to biases, especially regarding illness severity. Finally, the risk for chance associations was high due to the large number of risk factors used in bivariate analyses.

The researchers of the study concluded that mood disorders are highly associated with suicidal behaviors, with ideation highest in bipolar disorder type II and attempts and violent suicides highest in bipolar disorder type I. Risk factors strongly associated with suicidal acts differed between patients with bipolar disorder vs patients with depression.

Reference

Baldessarini RJ, Tondo L, Pinna M, Nuñez N, Vázquez GH. Suicidal risk factors in major affective disorders [published online July 11, 2019]. Br J Psychiatry. doi: 10.1192/bjp.2019.167