Hemostatic effects of third- and second-generation oral contraceptives: absence of a causal mechanism for a difference in risk of venous thromboembolism

Iron-Deficiency and Estrogen Are Associated With Ischemic Stroke by Up-Regulating Transferrin to Induce Hypercoagulability

RATIONALE

Epidemiological studies have identified an associate between iron deficiency (ID) and the use of oral contraceptives (CC) and ischemic stroke (IS). To date, however, the underlying mechanism remains poorly understood. Both ID and CC have been demonstrated to upregulate the level and iron-binding ability of Tf (transferrin), with our recent study showing that this upregulation can induce hypercoagulability by potentiating FXIIa/thrombin and blocking antithrombin-coagulation proteases interactions.

OBJECTIVE

To investigate whether Tf mediates IS associated with ID or CC and the underlying mechanisms.

METHODS AND RESULTS

Tf levels were assayed in the plasma of IS patients with a history of ID anemia, ID anemia patients, venous thromboembolism patients using CC, and ID mice, and in the cerebrospinal fluid of some IS patients. Effects of ID and estrogen administration on Tf expression and coagulability and the underlying mechanisms were studied in vivo and in vitro. High levels of Tf and Tf-thrombin/FXIIa complexes were found in patients and ID mice. Both ID and estrogen upregulated Tf through hypoxia and estrogen response elements located in the Tf gene enhancer and promoter regions, respectively. In addition, ID, administration of exogenous Tf or estrogen, and Tf overexpression promoted platelet-based thrombin generation and hypercoagulability and thus aggravated IS. In contrast, anti-Tf antibodies, Tf knockdown, and peptide inhibitors of Tf-thrombin/FXIIa interaction exerted anti-IS effects in vivo.

CONCLUSIONS

Our findings revealed that certain factors (ie, ID and CC) upregulating Tf are risk factors of thromboembolic diseases decipher a previously unrecognized mechanistic association among ID, CC, and IS and provide a novel strategy for the development of anti-IS medicine by interfering with Tf-thrombin/FXIIa interactions.

Patterns of prescription and discontinuation of contraceptives for Swedish women with obesity and normal-weight women

Purpose: This study aimed to explore the prescription of different contraceptive methods to Swedish women with obesity and to compare the pattern of prescription and adherence to treatment between this group and normal-weight women. Materials and methods: This study included 371 women with obesity and 744 matched normal-weight women, aged 18-40. Medical records were scrutinised for the period 1 January 2010 to 31 December 2014. The retrieved variables included: background characteristics, prescribed contraceptive methods, adverse effects, duration of treatment, reason for discontinuation and bleeding pattern. Result: Progestin-only pills were mainly prescribed to women with obesity (44% vs. 20%, p = 0.001) whereas combined hormonal contraception was mainly prescribed to normal-weight women (60% vs. 21%, p < 0.0001). Thirty-three percent vs. 25% (p = 0.003) discontinued their contraceptive method within 1 year. The most commonly declared reason for discontinuation was bleeding disturbance (14.7% vs. 9.6%, p = 0.008). Conclusion: The most commonly prescribed contraceptive method in women with obesity was progestin-only pills, but surprisingly many women with obesity were prescribed combined hormonal contraception despite current Swedish and European guidelines. Incident users with obesity were significantly more likely to discontinue their contraceptive method within the first year of the study period, compared with incident normal-weight users.

Comparison of the impact of four generations of progestins on hemostatic variables

This study was undertaken to evaluate the impact of progestins as part of low-estrogen (ethinyl estradiol [EE2] ≤35 μg) combined oral contraceptives (COCs) on hemostatic variables. One hundred ninety-five healthy women took oral contraceptives with following formulations: 35 EE2/norgestimate (NGM), 35 EE2/cyproterone acetate, 35 EE2/norethisterone, 30 EE2/levonorgestrel, 30 EE2/drospirenone (DRSP), 20 EE2/gestodene, and 20 EE2/DRSP, for 6 months. Hemostatic assays (prothrombin time, activated partial thromboplastin time, fibrinogen, resistance to activated protein C ratio, protein C, protein S, factor VIII [FVIII], antithrombin, plasminogen, α2-antiplasmin, inhibitor of plasminogen activator type 1 [PAI-1] and d-dimers) were performed in 3 time points: at baseline, after 3, and 6 cycles. For each formulation, results were compared according to baseline values, intergroup analysis, and the amount of estrogen or progestin component. Most of the variables were changed except FVIII. Significant difference between oral contraceptives was found in antithrombin, protein C, protein S activities, and PAI-1 values, but changes were mostly within reference range.

Venous thrombosis and oral contraceptives: current status

The use of oral contraceptives is associated with an increased risk of venous thrombosis. It is now generally accepted that women who use oral contraceptives that contain so-called third-generation progestins (desogestrel or gestodene) are exposed to a twofold higher risk of venous thrombosis than women who use oral contraceptives that contain the second-generation progestin levonorgestrel. Coagulation studies demonstrated that oral contraceptives increase the plasma level of prothrombin, decrease the level of protein S and induce acquired activated protein C resistance. The changes in hemostatic parameters can explain why women who use oral contraceptives are exposed to an increased risk of venous thrombosis and why the risk is further increased in third-generation oral contraceptive users.

Combined hormonal contraception and venous thromboembolism

This review provides an update of knowledge regarding venous thromboembolism (VTE) and combined hormonal contraceptives (CHCs) in the light of new progestins and new administration routes for CHCs. Practical recommendations are also offered. The association between the use of combined oral contraceptives (COCs) and an increased risk of VTE has been known about for many years, it being related mainly to the dose of oestrogen; however, recent research has also shown the influence of the type of progestin. When compared to COCs containing levonorgestrel or norethisterone, those containing desogestrel or gestodene present a two-fold greater risk of VTE; for COCs containing cyproterone acetate, the risk is four-fold greater, while there are no or insufficient data for those containing norgestimate, chlormadinone acetate or drospirenone. With regard to the contraceptive patch, the available data suggest that the risk of VTE is similar to that observed with COCs. There are no data concerning vaginal rings. The greatest risk of COC-associated VTE occurs during the first year of use, thus suggesting the existence of a predisposing condition, such as being a carrier of a thrombogenic mutation with which the COCs would exert a synergistic effect. Routine screening for such conditions is not justified. Changes in haemostatic variables produced by COCs, for example, acquired resistance to protein C, could be linked to VTE, although it has yet to be demonstrated that such alterations are related to a clinical risk of VTE among COC users. At present there are no laboratory tests able to detect an increased risk of VTE in asymptomatic women. The key procedures in terms of ensuring the safe use of this contraceptive method are a full clinical, personal and family history, in order to evaluate risk factors for VTE and cardiovascular disease, along with the recording of blood pressure and body mass index prior to the prescription of COCs.

The effects of two monophasic oral contraceptives containing 30 mcg of ethinyl estradiol and either 2 mg of chlormadinone acetate or 0.15 mg of desogestrel on lipid, hormone and metabolic parameters

BACKGROUND

This study was conducted to compare the effects of two monophasic oral contraceptives (OCs) containing ethinyl estradiol (EE) 30 mcg+either chlormadinone acetate (CMA) 2 mg (Belara) or 0.15 mg desogestrel (Marvelon) on lipid, hormone and other relevant metabolic parameters.

STUDY DESIGN

Markers of lipid and carbohydrate metabolism, and reproductive hormone levels, were measured in 45 subjects randomly assigned to 6 months of treatment with one of the two OCs. The cortisol response to adrenocorticotrophic hormone (ACTH) stimulation was also evaluated.

RESULTS

In both treatment groups, triglycerides, high-density lipoprotein cholesterol (HDL-C), apolipoprotein (Apo) AI and Apo AII levels increased; low-density lipoprotein cholesterol (LDL-C) and the LDL-C/HDL-C ratio decreased; and total cholesterol and lipoprotein(a) were unchanged during treatment. Effects on HDL-C, Apo AI, LDL-C and the LDL-C/HDL-C ratio were more evident in the EE 30 mcg+CMA 2 mg group. Follicle-stimulating hormone, luteinizing hormone and androgen levels decreased and sex hormone-binding globulin levels increased in both groups. Both OCs increased basal cortisol levels and cortisol response to ACTH. Oral contraceptive did not have a clinically significant impact on carbohydrate metabolism.

CONCLUSIONS

Both low-dose monophasic OCs had comparable effects on lipid, hormone and metabolic parameters during six cycles of treatment in healthy female subjects. There was some evidence of a beneficial effect on atherogenic cardiovascular risk markers, which was slightly more pronounced with EE 30 mcg+CMA 2 mg.

Effect of a low-dose oral contraceptive on venous endothelial function in healthy young women: preliminary results

BACKGROUND

A possible increase in the incidence of venous thromboembolic events has been reported among users of third generation oral contraceptives. The objective of this study was to evaluate the effect of a low dose oral contraceptive (15 microg ethinyl estradiol/60 microg gestodene) on the venous endothelial function of healthy young women.

METHODS

Prospective case control study using the dorsal hand vein technique. Venous endothelial function was evaluated at baseline and after 4 months in the oral contraceptive users group (11 women) and in a control group (9 women). After preconstriction of the vein with phenylephrine, dose-response curves for acetylcholine and sodium nitroprusside were constructed.

RESULTS

In the contraceptive users group, a reduction occurred in the maximum venodilation response to acetylcholine and sodium nitroprusside after 4 months of oral contraceptive use, but this difference was not statistically significant (P > 0.05). No significant changes were detected in maximum venodilation responses to acetylcholine and sodium nitroprusside at the 4-month time point in the control group.

CONCLUSION

This study found no significant impairment of endothelium-dependent or independent venodilation in healthy young women following oral contraceptive use. Further studies are necessary using the same methodology in a larger sample over a longer follow-up period.

Activated protein C resistance determined with a thrombin generation-based test predicts for venous thrombosis in men and women

Activated protein C (APC) resistance, determined with a thrombin-generation-based APC resistance test, may explain risk differences of venous thrombosis in users of second- and third-generation oral contraceptives (OC). To clinically validate this test, we analysed the Leiden thrombophilia case-control study (474 patients with a first episode of deep vein thrombosis and 474 age- and sex-matched control subjects). Data for men and women were analysed separately. As hormonal status in women is known to strongly influence the APC sensitivity ratio (APCsr), additional strata (OC use and menopausal state) were defined. The APCsr was higher in all patients than in control subjects. Odds ratios (OR), using the 90th percentile of all control subjects (APCsr > 4.5) as cut-off, were: 7.5 [95% confidence interval (CI) 1.6-33.8] for men, 3.0 (95% CI 1.0-8.8) for premenopausal women not using OC, 4.8 (95% CI 1.6-14.7) for premenopausal women using OC and 4.7 (95% CI 1.4-15.6) for postmenopausal women. After excluding the carriers of factor V Leiden, the OR became infinite for men (no control had an APCsr > 4.5), 1.4 (95% CI 0.2-8.2) for premenopausal women not using OC, 3.4 (95% CI 1.1-10.8) for premenopausal women using OC and 3.6 (95% CI 0.6-20.5) for postmenopausal women. A high APCsr, determined with the thrombin-generation-based APC resistance test, predicts venous thrombotic risk, in populations with and without factor V Leiden. In addition, acquired APC resistance resulting from OC use predicts an increased risk for venous thrombosis independent of factor V Leiden.

Deep venous thrombosis risk assessment, incidence, and prophylaxis in foot and ankle surgery

As discussed in this review, DVT and PE are dangerous clinical diagnoses that can occur following foot and ankle surgery. The authors have provided a clinical protocol, a risk assessment tool, and treatment guidelines for this condition that can be applied to the everyday practice of foot and ankle surgeons. Unlike recommendations in previous studies, the authors believe that podiatric and orthopedic surgeons operating on the foot and ankle should evaluate each patient carefully and consider pharmacologic prophylaxis against DVT formation when significant risk factors are present.

Acquired resistance to activated protein C in breast cancer patients

In 56 women with a lymph-node-positive breast carcinoma and 28 matched healthy control subjects, the sensitivity to activated protein C (APC-sr) was determined with an APC resistance test that quantifies the effect of APC on thrombin generation initiated via the extrinsic coagulation pathway. Carriers of the Factor V Leiden mutation were excluded from the study. Significant resistance to APC was found in the breast cancer patients: median APC-sr 2.02 vs 1.03 in the healthy control subjects (P < 0.001). No difference in APC-sr was found between patients with metastases and without metastases. In patients with metastases, protein S levels were significantly elevated compared with patients without metastases and healthy control subjects: 108.0%vs 96.0% and 94.5% (P = 0.008 and P = 0.007). The APC-sr correlated with protein S in the control subjects and in patients without metastases but not in patients with metastases. The disturbance of the haemostatic balance probed by the tissue-factor-based APC resistance test might contribute to the cancer-related hypercoagulability.

Progestin contraceptives

Progestin contraceptives offer unique advantages, allowing the clinician to tailor optimum regimens for selected women. This article reviews the various progestational drugs, regimens, and delivery systems available presently and in development, with reference to the clinical benefits and limitations of each method.

Long-term effects of combined oral contraceptives on markers of endothelial function and lipids in healthy premenopausal women

The aim of this prospective cross-over study was to investigate the effect of two low-dosed oral contraceptives on markers of endothelial function and plasma lipids. Twelve healthy, nonsmoking women (mean age: 21.7 years) were recruited from the family planning clinic of the university hospital Zurich. For 6 months the participants received a treatment with two contraceptive pills containing 30 microg ethinyl estradiol/150 microg levonorgestrel (three cycles) and 30 microg ethinyl estradiol/75 microg gestodene (three cycles). Plasma levels of endothelin-1, nitric oxide, cholesterol, and HDL were measurement before and during treatment with both oral contraceptive treatments. No significant changes in the plasma levels of nitric oxide and endothelin-1, both important regulators of the vascular tone, were observed during oral contraceptive use. A significant negative correlation was found between nitric oxide and endothelin-1 and nitric oxide and cholesterol. There was a positive correlation between endothelin-1 and cholesterol. In conclusion, the investigated contraceptive pills did not cause major changes in circulating nitric oxide and endothelin-1 plasma levels.