Predictors of Suicide Risk in Bipolar Disorder Vary by Sex

Predictors of suicide in patients with bipolar disorder vary by sex, suggest findings of a large cohort study published in Acta Psychiatria Scandinavica. This and other risk factors for suicide in bipolar disorder were also examined.

Patients with bipolar disorder face a risk for suicide that is up to 20 times greater than that of the general population. However, the specific factors that contribute to this risk are not necessarily comparable across all populations.

The authors used data from the Swedish National Quality Register for Bipolar Affective Disorder and the Cause of Death Register to determine which patients with bipolar disorder completed suicide between 2004 and 2014. During the ranged follow-up period, 90 of 12,850 patients died by suicide, including 55 men and 35 women. The authors included deaths with the International Statistical Classification of Diseases-10 (ICD-10) codes that indicate “definite suicide” and “death by self-harm with undetermined intent.”

Across the entire study population, the most statistically notable risk factors for completed suicide were criminal conviction (HR, 4.43), previous suicide attempts (HR, 4.10), comorbid substance use disorder (HR, 3.79), and involuntary commitment (HR,3.50). Male sex also carried a hazard ratio of 2.56.

Not all of these risks were significant across the sexes. Among men but not women, comorbid substance use disorder (HR, 4.20), involuntary commitment (HR, 4.30), ≥1 affective episode in the previous year (HR, 3.19) and living alone (HR, 2.71) predicted completed suicides.

For women only, criminal conviction (HR, 9.85), comorbid personality disorder (HR, 4.78), and ≥1 affective episode in the previous year (HR, 2.81) appeared to be risks.

The authors examined several factors that had no apparent association with suicide risk, including bipolar disorder subtype, comorbid eating disorders, age, and body mass index.

Some of the findings were inconsistent with previous investigations into bipolar disorder and suicide. At least 1 other study did not find that substance dependence predicted suicide risk, although research to date suggests that alcohol misuse is more common in men with bipolar disorder than women.

While the study was notable for its large, representative sample, the quality register did not include data on risk factors such as early life adversity, family history of suicide, and psychotic features.

Reference

Hannson C, Joas E, Pålsson E, Hawton K, Runeson B, Landén M. Risk factors for suicide in bipolar disorder: a cohort study of 12 850 patients [published online August 3, 2018]. Acta Psychiatr Scand. doi:10.1111/acps.12946