Atherogenic index of plasma as a cardiovascular risk marker in manic, depressive, and euthymic stages of bipolar disorder

OBJECTIVE
Individuals with bipolar disorder (BD) frequently suffer from cardiovascular disease (CVD), and it is a leading cause of mortality. Clinicians use routine laboratory tests, including a lipid profile, to predict cardiovascular risk. In addition, a particular lipid ratio, the atherogenic index of plasma (AIP), is a sensitive, new parameter that can be used to assess high-risk groups. To our knowledge, this is the first study evaluating cardiovascular risk via AIP in different stages of BD.

METHODS
The study group consisted of male patients with BD who were in a manic, depressive, or euthymic state, and age- and gender-matched healthy controls. Lipid profiles were analyzed and the AIP parameter of logarithm of triglyceride (TG) / high-density lipoprotein cholesterol (HDLc) was calculated for all of the participants. The significance level was set at p<0.05.

RESULTS
A total of 44 BD patients experiencing a manic episode, 35 depressive BD patients, 42 euthymic patients, and 41 healthy controls matched for age, gender, and smoking status were enrolled in the study. The AIP level was significantly different between groups (p=0.009). Pairwise comparisons of the groups revealed that the AIP level of depressive patients was significantly higher than that of the manic, euthymic, and control groups (p=0.013, p=0.048, and p=0.021, respectively). The AIP level was positively correlated with body mass index, waist circumference, metabolic syndrome, total cholesterol, low-density lipoprotein, and triglyceride level, and was negatively correlated with the HDLc level.

CONCLUSION
In this study, male BD patients in a depressive episode demonstrated an increase in cardiovascular risk. The significant correlations between AIP and other conventional cardiovascular risk factors indicate that AIP may be more useful to identify individuals with BD at high risk for CVD than absolute lipid parameters.