Type 2 diabetes adds to hospital mortality risk in bipolar patients

By Eleanor McDermid, Senior medwireNews Reporter

Type 2 diabetes is a major contributor to mortality in patients with bipolar disorder who are admitted to general hospitals, a study shows.

Dieter Schoepf and Reinhard Heun (University of Bonn, Germany) assessed outcomes of 621 bipolar disorder patients hospitalised for nonpsychiatric reasons over a 12.5-year period, including 60 who died in hospital, and 6210 control patients matched for age and gender.

In keeping with their expectations, the researchers found that the bipolar disorder patients were often admitted in a more serious condition than controls, remained in hospital longer and were more likely to die in hospital, at an unadjusted rate of 9.7% compared with 8.4% in controls.

Eighteen physical comorbidities were significantly more common in the bipolar disorder patients than controls, with the three most common being asthma (14.5 vs 7.4%), Type 2 diabetes (12.6 vs 8.0%) and chronic obstructive pulmonary disease (COPD; 7.6 vs 2.6%).

Many of these conditions, including diabetes and COPD, contributed to hospital-based mortality in the bipolar disorder group. Hypertension was the most prevalent comorbidity contributing to mortality in bipolar disorder patients, being present in 35.0% of those who died. And COPD had the largest impact, increasing mortality risk threefold.

But hypertension was also highly prevalent in the control group, and COPD had a similar size of impact on bipolar patients and controls. By contrast, Type 2 diabetes was the only comorbidity with a significant effect on mortality in bipolar patients alone. It was present in 25.0% of deceased bipolar patients, compared with 11.2% of survivors, giving a significant 2.1-fold increased mortality risk, but was only present in 14.6% of deceased controls.

These associations were independent of confounding variables, including age, which was significantly older among deceased bipolar patients than survivors, the team reports in the Journal of Affective Disorders.

The researchers note that diabetes is an important risk factor for ischaemic stroke, which in turn was a significant contributor to mortality in both bipolar and control patients, and that hyperglycaemia may also contribute to respiratory mortality, such as pneumonia.

They conclude: “The study gives support for an aggressive multidisciplinary approach to identify and treat [Type 2 diabetes] to prevent diabetic, respiratory and vascular complications in all individuals with [bipolar disorder].”

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