External Causes of Death More Likely in Those With Bipolar Disorder

While bipolar disorder is known to be associated with early mortality, deaths are more likely to be caused by external factors, such as suicide, than somatic factors, such as alcohol-related diseases, according to a Finnish nationwide cohort study.

In the cohort of people ages 15 to 64, those with bipolar disorder had six-fold higher mortality due to external causes (standardized mortality ratio [SMR] 6.01, 95% CI 5.68-6.34) and two-fold higher mortality due to somatic causes (SMR 2.06, 95% CI 1.97-2.15) compared with those without the disorder, reported Tapio Paljärvi, PhD, of Niuvanniemi Hospital in Kuopio, Finland, and co-authors.

Overall, all-cause mortality was almost three-fold higher (SMR 2.76, 95% CI 2.67-2.85) among people with bipolar disorder versus those without the condition, they noted in BMJ Mental Health.

Of the deaths due to external causes, 83% were excess deaths, while 51% of the deaths due to somatic causes were excess.

All-cause mortality among individuals with bipolar disorder is consistently reported to be about two-fold higher compared with the general population, the authors said. The increasing mortality gap between people with bipolar disorder and the general population has been reported in some countries, while stable or decreasing trends have been reported in others.

“Focusing on age-specific absolute and relative mortality reveals important aspects of the mortality gap,” Paljärvi told MedPage Today in an email. “In those aged under 65 years, the excess mortality observed in bipolar disorder was to a large extent driven by external causes of death, including suicides and accidents, and by alcohol abuse.”

He pointed out that most of the excess deaths in those ages 15 to 44 were due to external causes, while external causes and somatic causes contributed equally to the excess mortality in those ages 45 to 64 years.

Most of the excess deaths due to somatic causes were related to alcohol (40%), cardiovascular disease (26%), or cancer (10%). Meanwhile, 61% of the excess deaths due to external causes were related to suicide.

“We showed that the excess mortality due to alcohol was substantial, particularly in the older age groups,” Paljärvi said. “The role of alcohol abuse, and of other substances, is likely underestimated because alcohol is a contributory factor also in various other causes of death that are not explicitly defined as related to alcohol.”

These findings showed that more targeted approaches are necessary to help predict and prevent these excess deaths, especially related to alcohol and suicide-related causes, he added.

“A key implication is the need for personalized approaches to risk prediction and prevention in the treatment and management of bipolar disorder,” Paljärvi said. “Both acute and long-term risks of adverse health outcomes associated with bipolar disorder need to be considered throughout the treatment.”

“These results call for a holistic approach to treatment and management of bipolar disorder,” he continued. “In clinical practice, a stronger emphasis on identifying and treating comorbid substance abuse is warranted.”

He urged mental health providers to carefully consider the balance between therapeutic response and the potential long-term somatic side effects of medications, such as adverse cardiometabolic effects, to prevent premature mortality in patients with bipolar disorder.

For this study, the researchers included individuals with and without a diagnosis of bipolar disorder who were ages 15 to 64 during 2004 to 2018.

They identified all individuals with a first diagnosis of bipolar disorder from 1998 to 2018 based on ICD-10 criteria. They were followed until they reached their 65th birthday, were diagnosed with schizophrenia-spectrum disorders, died, or the end of 2018.

Of the 47,018 individuals with bipolar disorder in the study, 57% were women, and mean age at the beginning of follow-up was 38. The median follow-up period was about 8 years.

Among the individuals with bipolar disorder, 7% died during follow-up.

Paljärvi and team noted that the mortality estimates for people with bipolar disorder may be underestimated because they could not quantify how many people in the general population were either not diagnosed or were misdiagnosed.