Multinational, multicentre, randomised, open-label study evaluating the impact of a 91-day extended regimen combined oral contraceptive, compared with two 28-day traditional combined oral contraceptives, on haemostatic parameters in healthy women.

Objectives: To evaluate the impact of a 91-day extended regimen combined oral contraceptive (150 μg levonorgestrel [LNG]/30 μg ethinylestradiol [EE] for 84 days, followed by 10 μg EE for seven days [Treatment 1]) compared with two traditional 21/7 regimens (21 days 150 μg LNG/30 μg EE [Treatment 2] or 150 μg desogestrel [DSG]/30 μg EE [Treatment 3], both with seven days' hormone free), on several coagulation factors and thrombin formation markers.

Methods: Randomised, open-label, parallel-group comparative study involving healthy women (18-40 years). The primary endpoint was change from baseline in prothrombin fragment 1 + 2 (F1 + 2) levels over six months.

Results: A total of 187 subjects were included in the primary analysis. In all groups, mean F1 + 2 values were elevated after six months of treatment. Changes were comparable between Treatments 1 and 2 (least squares mean change: 170 pmol/L and 158 pmol/L, respectively) but noticeably larger after Treatment 3 (least squares mean change: 592 pmol/L). The haemostatic effects of Treatment 1 were comparable to those of Treatment 2 and noninferior to those of Treatment 3 (lower limit of 95% confidence interval [- 18.3 pmol/L] > - 130 pmol/L).

Conclusions: The LNG/EE regimens had similar effects on F1 + 2. Noninferiority was demonstrated between extended regimen LNG/EE and DSG/EE.