Effects of switching from oral to transdermal or transvaginal contraception on markers of thrombosis

Abstract

Background: The study was conducted to determine the impact of switching from oral to transdermal patch or vaginal ring contraception on biomarkers of thrombosis.

Study design: Current healthy oral contraceptive (OC) users were randomized to switch to either a contraceptive ring (CR) or patch (CP) and underwent phlebotomy to measure surrogate biomarkers of thrombosis [sex hormone-binding globulin (SHBG), free protein S and activated protein C resistance (APC-r)] before switching, and during the fourth cycle of use of the new method.

Results: Of 142 reproductive age women enrolled, 120 sample pairs were available for analysis. SHBG increased significantly from baseline in CP users [mean change (95% CI), +29.9 nM (9.6-50)] but not in CR users [-1.6 (-16.6 to 13.5)]. Protein S decreased significantly from baseline in CP users [mean change -7.1% (-12.1 to -2.1)], but increased significantly in CR users [+5.3% (1.1-9.6)]. The APC-r ratio did not undergo a significant change from baseline in either group [CP +0.06 (-0.06 to 0.18), CR +0.02 (-0.10 to 0.14)]. Compared to CR users, subjects using the CP had significantly higher SHBG [187.5 (167.0-208), 146 (132.6-159.4), p=.012], significantly lower protein S [81.8 (76.8-86.8), 93.6 (89.1-98.1), p=.001] and similar APC-r ratios [2.99 (2.85-3.14), 3.09 (2.96, 3.22), p=.3] at the Cycle 4 visit.

Conclusion: OC users who switch to the ring exhibit beneficial changes in biomarkers of thrombosis, while those switching to the patch display a shift favoring clot formation.

Conflict of interest statement

Conflict of interest

Dr. Jensen: research funding: Berlex (Bayer), Organon, Galen, Symbollon, Wyeth, Pfizer, Novartes; speakers bureau: Berlex (Bayer), Wyeth; consulting: Berlex (Bayer), Wyeth, Novartes

Dr. Burke: research funding: Organon, Duramed, Berlex

Dr. Barnhart: research funding: Organon, Wyeth-Ayerst, Johnson & Johnson, Duramed, Xanodyne, Boehringer Ingelheim, Third Wave, Pfeizer, MGI Pharma; speakers bureau: Organon; consulting: Novo Nordisk

Dr. Peters, Ms. Messerle-Forbes, Ms. Tillotson: No conflicts

Figures

Fig. 1

Enrollment in substudy, and samples available for evaluation.

Fig. 2

A simplified illustration of the coagulation cascade. Activated protein C (APC) exerts an anticoagulant effect primarily through inhibition of factor V. Protein S is required for this interaction.