The significantly increased risk of myocardial infarction or stroke in patients with bipolar I disorder appears to be tied more to preventive factors than to cardiovascular risk factors. However, bipolar I patients with a history of psychosis have an marginally increased risk of MI or stroke, a population-based cohort study showed.
The researchers came to those conclusions after analyzing residents’ health records and death certificates in Olmsted County, Minn., which were contained within the Rochester Epidemiology Project database. The study’s participants included 334 patients with bipolar I disorder and 334 people without bipolar disorder, although one of the patients who did not have bipolar I at the beginning of the study was later diagnosed with the disorder. All participants had been residents of Olmsted County from Jan. 1, 1966, through Dec. 31,1996.
Patients continued to be followed until Dec. 31, 2013, unless one of the following events occurred before that date: the patient had an MI or stroke, was lost to follow-up, or died before the end of the study. A patient experiencing an MI, stroke, or death or a patient disappearing from the database triggered an end to that patient’s participation in the study.
When an individual having an MI or a stroke was treated as a composite outcome, bipolar I disorder patients had a significantly increased risk of experiencing a fatal or non-fatal MI or stroke, compared with the individuals in the control group (P = .04). The risk was no longer significant after the researchers adjusted for the following potential baseline confounders of the association between bipolar disorder and cardiovascular disease: alcohol use disorder, diabetes, hypertension, and smoking (P = .46).
Meanwhile, a secondary analysis of the data showed that history of psychosis was indeed tied to a marginally increased risk of MI or stroke (P =.06).
“It will be fundamental to improve current preventive strategies to decrease the prevalence of smoking, alcohol use, hypertension, and diabetes among patients with bipolar disorder,” said Dr. Miguel L. Prieto of the department of psychiatry and psychology at the Mayo Medical School, Rochester, Minn., and his colleagues. “Moreover, we detected a possible higher risk of MI/stroke in the subgroup of patients with history of psychosis that certainly warrants replication.”
Future research also should seek to determine early biomarkers of atherosclerosis, the researchers said.
Read the study in Journal of Affective Disorders (doi: 10.1016/j.jad.2016.01.015).