The atherogenic index of plasma is increased by hormonal contraception

Oral contraceptives are known to induce secondary dyslipidemia. The aim of this study was to determine if hormonal contraceptives affect the new atherogenic index of plasma (AIP) = log[triglycerides (TG)/high-density lipoprotein cholesterol (HDL-C)] together with the total cholesterol/HDL-C (TC/HDL-C) and the apolipoprotein B/apolipoprotein A1 (apoB/apoA1) ratios.

This study included 43 healthy women. Blood lipids, apoA1, apoB and the high-sensitivity C-reactive protein (hsCRP) concentration were examined before the start of hormonal contraception and after 3, 6 and 9 months of its regular use. AIP, the apoB/apoA1 ratio and the TC/HDL-C ratio were calculated.

After 9 months of continued hormonal contraception, we found significantly increased levels of TC, HDL-C, low-density lipoprotein cholesterol (LDL-C), TG, apoA1 and apoB (p < 0.05 for all analytes). The TC/HDL-C and apoB/apoA1 ratios remained unchanged; however, the AIP and the hsCRP concentration increased significantly (p < 0.005 and p < 0.006). LDL-C increased slightly over the first three examinations (0, 3, 6 months), and the rest of the indices increased over the first two examinations (0, 3 months) and maintained stable values through the fourth examination (9 months).

The increased AIP and hs-CRP concentration after 9 months of hormonal contraception demonstrate that contraceptive-induced dyslipidemia has a proatherogenic nature, even when the TC/HDL-C and the apoB/apoA1 ratios are unchanged.