The Level of Cardiovascular Risk Factors in Bipolar Disorder Equals That of Schizophrenia: A Comparative Study

Objective: In schizophrenia, increased rates of somatic mortality have been shown to correspond with a high prevalence of cardiovascular risk factors, including smoking and the metabolic syndrome. In bipolar disorder, the amount of cardiovascular risk is still largely unknown. This study compares the prevalence of smoking and metabolic disturbances in bipolar disorder and schizophrenia in a representative sample of patients under naturalistic conditions. It also compares the prevalence of risk factors in each diagnostic group with the general population.

Method: Longitudinal data on clinical groups from October 2002 through December 2005 were from the Oslo TOP Study (DSM-IV bipolar disorder [N = 110] and schizophrenia [N = 163]). Reference data were from the 2000 to 2001 Oslo Health Study (18,770 individuals of the same area). Background variables, prevalence of smoking, and age-adjusted levels of metabolic risk factors were compared between diagnostic groups. Risk factors in both groups were then compared with the general population.

Results: Patients with bipolar disorder had higher levels of education, better social functioning, fewer psychiatric symptoms, and less use of medication than patients with schizophrenia. There was no significant difference between diagnostic groups in the prevalence of smoking, obesity, metabolic syndrome, or diabetes. The mean level of high density lipoprotein cholesterol was lower in schizophrenia (p < .001), and systolic blood pressure was higher in bipolar disorder (p < .05). Both diagnostic groups had a prevalence of cardiovascular risk factors about twice that of the general population.

Conclusion: The prevalence of cardiovascular risk factors was alarmingly high for bipolar disorder and schizophrenia patients compared with the general population, and the prevalence was approximately the same in both diagnostic groups.