Effect of second- and third-generation oral contraceptives on fibrinolysis in the absence or presence of the factor V Leiden mutation

Elucidating the molecular mechanisms of fibrinolytic shutdown after severe injury: The role of thrombin-activatable fibrinolysis inhibitor

BACKGROUND

The mechanisms underlying trauma-induced coagulopathy remain elusive. Hyperfibrinolysis has been linked to increased plasminogen activation and antiprotease consumption; however, the mechanistic players in its counterpart, fibrinolysis shutdown, remain unclear. We hypothesize that thrombin-activatable fibrinolysis inhibitor (TAFI) plays a major role in fibrinolytic shutdown after injury.

METHODS

As part of this observational cohort study, whole blood was collected from trauma activation patients at a single, level 1 trauma center. Citrated rapid thrombelastography and the following enzyme-linked immunosorbent assays were conducted: thrombin, antithrombin, thrombin-antithrombin complex, TAFI, plasminogen, antiplasmin, plasmin-antiplasmin (PAP), tissue plasminogen activator, plasminogen activator inhibitor 1, and tissue plasminogen activator-plasminogen activator inhibitor 1 complex. Univariate and cluster analysis were performed.

RESULTS

Overall, 56 patients (median age, 33.5 years; 70% male) were included. The majority (57%) presented after blunt mechanism and with severe injury (median New Injury Severity Score, 27). Two clusters of patients were identified: Group 1 (normal fibrinolysis, n = 21) and Group 2 (fibrinolysis shutdown, n = 35). Group 2 had significantly lower fibrinolysis with a median LY30 of 1.1% (interquartile range [IQR], 0.1-1.9%) versus 2.1% (IQR, 0.5-2.8%) in Group 1; while the median LY30 was within physiologic range, 45% of patients in Group 2 were in shutdown (vs. 24% in Group 1, p = 0.09). Compared with Group 1, Group 2 had significantly higher PAP (median, 4.7 [IQR, 1.7-9.3] vs. 1.4 [1.0-2.1] μg/mL in Group 1; p = 0.002) and higher TAFI (median, 152.5% [IQR, 110.3-190.7%] vs. 121.9% [IQR, 93.2-155.6%]; p = 0.04). There was a strong correlation between PAP and TAFI ( R2 = 0.5, p = 0.0002).

CONCLUSION

The presented data characterize fibrinolytic shutdown, indicating an initial plasmin burst followed by diminished fibrinolysis, which is distinct from hypofibrinolysis (inadequate plasmin burst and fibrinolysis). After an initial thrombin and plasmin burst (increased PAP), fibrinolysis is inhibited, mediated in part by increased TAFI.

Combined oral contraceptives: venous thrombosis

BACKGROUND

Combined oral contraceptive (COC) use has been associated with venous thrombosis (VT) (i.e., deep venous thrombosis and pulmonary embolism). The VT risk has been evaluated for many estrogen doses and progestagen types contained in COC but no comprehensive comparison involving commonly used COC is available.

OBJECTIVES

To provide a comprehensive overview of the risk of venous thrombosis in women using different combined oral contraceptives.

SEARCH METHODS

Electronic databases (Pubmed, Embase, Web of Science, Cochrane, CINAHL, Academic Search Premier and ScienceDirect) were searched in 22 April 2013 for eligible studies, without language restrictions.

SELECTION CRITERIA

We selected studies including healthy women taking COC with VT as outcome.

DATA COLLECTION AND ANALYSIS

The primary outcome of interest was a fatal or non-fatal first event of venous thrombosis with the main focus on deep venous thrombosis or pulmonary embolism. Publications with at least 10 events in total were eligible. The network meta-analysis was performed using an extension of frequentist random effects models for mixed multiple treatment comparisons. Unadjusted relative risks with 95% confidence intervals were reported.Two independent reviewers extracted data from selected studies.

MAIN RESULTS

3110 publications were retrieved through a search strategy; 25 publications reporting on 26 studies were included. Incidence of venous thrombosis in non-users from two included cohorts was 0.19 and 0.37 per 1 000 person years, in line with previously reported incidences of 0,16 per 1 000 person years. Use of combined oral contraceptives increased the risk of venous thrombosis compared with non-use (relative risk 3.5, 95% confidence interval 2.9 to 4.3). The relative risk of venous thrombosis for combined oral contraceptives with 30-35 μg ethinylestradiol and gestodene, desogestrel, cyproterone acetate, or drospirenone were similar and about 50-80% higher than for combined oral contraceptives with levonorgestrel. A dose related effect of ethinylestradiol was observed for gestodene, desogestrel, and levonorgestrel, with higher doses being associated with higher thrombosis risk.

AUTHORS' CONCLUSIONS

All combined oral contraceptives investigated in this analysis were associated with an increased risk of venous thrombosis. The effect size depended both on the progestogen used and the dose of ethinylestradiol. Risk of venous thrombosis for combined oral contraceptives with 30-35 μg ethinylestradiol and gestodene, desogestrel, cyproterone acetate and drospirenone were similar, and about 50-80% higher than with levonorgestrel. The combined oral contraceptive with the lowest possible dose of ethinylestradiol and good compliance should be prescribed-that is, 30 μg ethinylestradiol with levonorgestrel.

Thrombophilia and the risk of thromboembolic events in women on oral contraceptives and hormone replacement therapy

Thrombophilia contributes to the risk of thrombosis in women using female hormones. The objective of the present study was to evaluate the prevalence of thrombophilia in women with thromboembolic events (TEEs) using oral contraceptives or hormone replacement therapy (HRT) and assess the contribution of a family history and the duration of hormone use in predicting thrombosis. A retrospective analysis was performed of the case records of women who developed a TEE while on oral contraceptives or HRT and were referred for thrombophilia evaluation over a 4-year period. Among 85 women who developed a TEE while on oral contraceptives or HRT, 65 had at least one additional thrombophilia risk factor. Of the 85 cases, 23 tested positive for more than two thrombophilias, 16 had factor V Leiden, five had the prothrombin gene G20210A polymorphism, 26 had antiphospholipid antibodies, 10 had elevated homocysteine, four had protein C deficiency, and seven had protein S deficiency. There were 64 TEE: 16 pulmonary emboli, 17 cerebrovascular events, 11 intra-abdominal thromboses, 13 deep venous thromboses, five cases of superficial thrombophlebitis, and two retinal vein thromboses. Of the 65 women, 37% had a positive family history of thrombosis. Approximately half of the women had been taking oral contraceptives or HRT for more than 1 year. There is a high prevalence of thrombophilia in women who developed a TEE while using oral contraceptives or HRT for more than 1 year. Family and personal history of thrombosis should be carefully evaluated in all women before initiating or continuing oral contraceptives or HRT, and a positive history may warrant a thrombophilia screening.

Oral contraception and thrombophilia

PURPOSE OF REVIEW

To describe current knowledge related to the association between oral contraception and the thrombophilias.

RECENT FINDINGS

The use of oral contraception increases the risk of venous thromboembolism as well as arterial thrombosis. Third-generation pills seem to increase the risk of venous thromboembolism compared with second-generation pills. This effect seems to be reversed or absent for the risk of arterial thrombosis. The effect of oral contraception on the risk of venous thromboembolism is more pronounced during the first year of use. All these risks are further increased in patients with an inborn or acquired tendency for coagulation (thrombophilia).

SUMMARY

Prospective users of oral contraception are potential candidates for screening/testing, because a positive screen may substantially decrease the risk of a thrombotic event. At present, the available testing methods are not cost effective, and the absolute risk is not defined for each thrombophilia. Until these shortcomings are solved, it is not recommended to test every woman who wishes to use oral contraception. Nevertheless, before starting on oral contraception, each patient should be carefully screened by a physician who should identify an increased risk of thrombophilia and tailor the laboratory testing.

Curiouser and curiouser: recent advances in measurement of thrombin-activatable fibrinolysis inhibitor (TAFI) and in understanding its molecular genetics, gene regulation, and biological roles

The thrombin-activatable fibrinolysis inhibitor (TAFI) pathway defines a novel molecular connection between blood coagulation and both fibrinolysis and inflammation. TAFI is a plasma zymogen that can be activated by thrombin, the thrombin-thrombomodulin complex, or plasmin. The activated form of TAFI (TAFIa) attenuates fibrinolysis by removing the carboxyl-terminal lysine residues from partially degraded fibrin that mediate positive feedback in the fibrinolytic cascade. A role for TAFIa in modulating inflammation is suggested by the ability of this enzyme to down-regulate pericellular plasminogen activation and to inactivate the inflammatory peptides bradykinin and the anaphylatoxins C3a and C5a. The focus of this review is on recent advances in the clinical measurement of the TAFI pathway in human subjects and what this has revealed in terms of the molecular genetics of TAFI, the biological variation in plasma TAFI antigen levels, potential regulators of expression of the gene encoding TAFI, and the TAFI pathway as a risk factor for the development of vascular diseases. Although this field is in its infancy, much recent progress has been made and the available data suggest that the TAFI pathway is an intriguing new player in a variety of physiological and pathophysiological contexts.

The effects of short-term raloxifene therapy on fibrinolysis markers: TAFI, tPA, and PAI-1

BACKGROUND

Markers of fibrinolysis, thrombin-activatable fibrinolysis inhibitor (TAFI), tissue-type plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) levels were studied for the evaluation of short-term effects of raloxifene administration in postmenopausal women.

METHODS

Thirty-nine postmenopausal women with osteopenia or osteoporosis were included in this prospective, controlled clinical study. Twenty-five women were given raloxifene hydrochloride (60 mg/day) plus calcium (500 mg/day). Age-matched controls (n = 14) were given only calcium. Plasma TAFI, tPA, and PAI-1 antigen levels were measured at baseline and after 3 months of treatment by commercially available ELISA kits. Variations of individuals were assessed by Wilcoxon's test. Relationship between those markers and demographic characteristics were investigated.

RESULTS

Three months of raloxifene treatment was associated with a significant decrease in the plasma TAFI antigen concentrations (16% change, P < 0.01), and a significant increase in tPA antigen concentrations (25% change, P < 0.05). A significant correlation was found between baseline TAFI antigen concentrations and the duration of amenorrhea (P < 0.05; r = 0.33).

CONCLUSION

We suggest that the increased risk of venous thromboembolism due to raloxifene treatment may be related to increased tPA levels, but not TAFI levels.

Pharmacogenetic aspects of the use of oral contraceptives and the risk of thrombosis

Oral contraceptives are currently used by more than 100 million women in developed countries and are a highly efficacious method to prevent undesired pregnancies. However, oral contraceptives are associated with an increased risk of venous and arterial thrombosis, through changes in blood coagulation and fibrinolysis. In order to reduce such complications, the composition of oral contraceptives has changed over the past decades, both for the dose of oestrogen and the type of progestagen. However, the risk for venous thromboembolism remains, particularly for women who are carriers of inherited thrombophilia. In these women, prescription of oral contraceptives should be carried out on an individual basis. This review illustrates the risk of thrombosis, particularly venous thromboembolism, associated with the use of oral contraceptives, underlines the crucial role of the interaction of these drugs with other risk factors for the disease, and gives suggestions on the utility of thrombophilia screening before prescription.

Venous thrombosis and changes of hemostatic variables during cross-sex hormone treatment in transsexual people

The incidence of venous thrombosis associated with estrogen treatment in male-to-female (M-->F) transsexuals is considerably higher with administration of oral ethinyl estradiol (EE) than with transdermal (td) 17-beta-estradiol (E(2)). To find an explanation for the different thrombotic risks of oral EE and td E(2) use, we compared the effects of treatment of M-->F transsexuals with cyproterone acetate (CPA) only, and with CPA in combination with td E(2), oral EE, or oral E(2) on a number of hemostatic variables [activated protein C (APC) resistance and plasma levels of protein S, protein C, and prothombin], all of which are documented risk factors for venous thrombosis. APC resistance was determined by quantification of the effect of APC on the amount of thrombin generated during tissue factor-initiated coagulation; plasma levels of total and free protein S were determined by standard ELISA; and levels of prothrombin and protein C were determined with functional assays after complete activation of the zymogens with specific snake venom proteases. CPA-only, td-E(2)+CPA, or oral-E(2)+CPA treatment produced rather small effects on hemostatic variables, whereas oral EE treatment resulted in a large increase in APC resistance from 1.2 +/- 0.8 to 4.1 +/- 1 (P < 0.001), a moderate increase in plasma protein C (9%; P = 0.012), and a large decrease in both total and free plasma protein S (30%; P < 0.005). The large differential effect of oral EE and oral E(2) indicates that the prothrombotic effect of EE is due to its molecular structure rather than to a first-pass liver effect (which they share). Moreover, these differences may explain why M-->F transsexuals treated with oral EE are exposed to a higher thrombotic risk than transsexuals treated with td E(2). Testosterone administration to female-to-male transsexuals had an antithrombotic effect.

Thrombophilias and gynaecology

In gynaecology, women are exposed to sex steroids when using oral contraceptives, hormone replacement therapy or when undergoing in vitro fertilization treatment and ovulation induction. Oral contraceptives and the use of hormone replacement therapy increase the risk of venous thrombosis. The risk is highest in the first year of use and higher among women with clotting defects. Women taking third-generation oral contraceptives have an almost twofold increased risk of venous thrombosis compared with those taking second-generation oral contraceptives. Inherited clotting defects, which are themselves risk factors of venous thrombosis, (e.g. factor V Leiden mutation, deficiency of protein C, protein S or antithrombin, high plasma levels of factor VIII, and prothrombin mutation) appear synergistically increase the risk of venous thrombosis caused by oral contraceptives. Recent studies also point to an interaction between hormone replacement therapy and coagulation defects in causing venous thrombosis. Emerging studies show that in vitro fertilization treatment and ovulation induction are also risk factors for venous thrombosis; the role of coagulation defects in this association is not yet clear.