Depressive traits linked to greater suicide risk in bipolar disorder

By Laura Cowen, medwireNews Reporter

Previous suicide attempts, recent affective episodes and recent psychiatric inpatient care are the strongest indicators that a patient with bipolar disorder may attempt suicide, show results of a large Swedish study.

This implies that clinicians should “pay attention to the risk of suicidal behaviour in bipolar patients with depressive features and more severe or unstable forms of the disorder”, write Dag Tidemalm (Karolinska Institutet, Stockholm) and co-researchers in PLOS ONE.

The researchers looked at 18 risk factors that they thought might be associated with attempted suicide in 6086 patients (60% women) registered in the Swedish National Quality Register for Bipolar Disorder between 2004 and 2011. The patients were followed up annually from 2005 to 2012, with a median follow-up period of 2.4 years.

During follow-up, there were 13 fatal and 338 nonfatal suicide attempts, and the rate of attempted suicide was significantly higher in women than men, at 6.9% versus 4.1%.

Having a previous suicide attempt at baseline was the strongest predictor of attempted suicide during follow-up, with odds ratios (ORs) of 3.93 and 4.24 in men and women, respectively.

Affective episodes in the year before baseline were associated with a 3.63-fold increased likelihood of a suicide attempt during follow-up among men and a 2.81-fold increased likelihood among women. The corresponding ORs associated with psychiatric inpatient care during the year before baseline were 3.57 and 2.68.

Having at least four depressive episodes prior to baseline approximately doubled the likelihood of a suicide attempt in both men and women, while multiple mixed episodes were associated with suicide attempts in women only (OR=1.40). No associations were observed for manic episodes in either gender.

“These results point to the fundamental importance of observing signs of depressive symptomatology and supplying adequate treatment, in the follow-up of bipolar patients”, Tidemalm et al remark.

Eating disorders and complicating social factors were also associated with suicide attempts in both men and women, but substance abuse was only a risk factor for men, and early onset of disease and having personality disorder were only significant in women.

The researchers say that the differing risk pattern between men and women is a “novel finding” that warrants further investigation.

Others variables that were investigated but showed no association with the likelihood of a suicide attempt included a family history of affective disorder, complicating somatic factors and violent behaviour.

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