Background: The effects of extended regimens of combined oral contraceptives (COC) on lipid parameters are largely unknown. The present study compared the effects of a COC containing 30 mcg ethinyl estradiol and 2 mg dienogest (EE/DNG) in conventional and extended-cycle regimen over 1 year.
Study design: Lipid parameters were measured in 59 women treated with EE/DNG either conventionally (21+7 days) or in extended-cycle regimen (84+7 days). Blood samples were taken in a control cycle and at 3 and 12 months of treatment.
Results: The mean levels of total cholesterol, HDL cholesterol and HDL(2) cholesterol underwent modest to moderate significant increases over time, while the significant increase in triglycerides and VLDL cholesterol was more pronounced with both regimens. LDL cholesterol decreased slightly in both regimen groups, whereas lipoprotein(a) was transiently decreased at 3 months only in the extended-cycle group. The changes reached a steady-state at latest at 3 months, but did not exceed the given normal ranges for any of the parameters. Notably, except for lipoprotein(a), the changes in mean lipid levels were not significantly different in the conventional and the extended-cycle regimen at 3 or 12 months of treatment.
Conclusion: Use of EE/DNG in conventional or extended-cycle regimen resulted in comparable changes of lipid parameters.