Interaction between the G20210A mutation of the prothrombin gene and oral contraceptive use in deep vein thrombosis

The risk of venous thromboembolism in oral contraceptive users: the role of genetic factors-a prospective cohort study of 240,000 women in the UK Biobank

BACKGROUND

More than 150 million women worldwide use oral contraceptives. Women with inherited thrombophilia and carriers of certain thrombophilia gene variants, such as factor V Leiden and the prothrombin, are at an increased risk for venous thromboembolism, especially when combined with oral contraceptive use. Venous thromboembolism is a complex disorder involving many genetic risk factors, and recently, polygenic risk scores have been proposed to capture a significant proportion of the genetic risk of venous thromboembolism.

OBJECTIVE

The aim of this study was to estimate the risk for developing venous thromboembolism when initiating oral contraceptive use (first 2 years) and during continued use among women with a high genetic liability.

STUDY DESIGN

We used a prospective study design in which 244,420 participants from the UK Biobank were followed from birth. The effect of oral contraceptive use during the first 2 years and in the remaining years of oral contraceptive use on the risk of developing venous thromboembolism was estimated using a Cox regression with a time-dependent exposure variable. Women were stratified according to their polygenic risk scores and whether they were carriers of factor V Leiden and/or prothrombin variants.

RESULTS

When genetic risk was not considered, an increased risk for venous thromboembolism was observed during the first 2 years of oral contraceptive use (hazard ratio, 3.09; 95% confidence interval, 3.00-3.20) but not during continued use (hazard ratio, 0.92; 95% confidence interval, 0.80-1.05). However, when genetic risk was considered, women in the highest polygenic risk score category had a more pronounced risk of developing a venous thromboembolism during the first 2 years of oral contraceptive use (hazard ratio, 6.35; 95% confidence interval, 4.98-8.09), and a high risk was also observed among factor V Leiden (hazard ratio, 5.73; 95% confidence interval, 5.31-6.17) and prothrombin variant carriers (hazard ratio, 5.23; 95% confidence interval, 4.67 - 5.87). A high polygenic risk score in combination with being a factor V Leiden and prothrombin variant carrier conferred the highest risk for developing a venous thromboembolism during the first 2 years of oral contraceptive use (hazard ratio, 14.8; 95% confidence interval, 9.28-23.6). Women with a high genetic liability also had an increased risk during continued use but it was less pronounced, and the highest risk was conferred to carriers of both factor V Leiden and the prothrombin variant (hazard ratio, 4.93; 95% confidence interval, 3.16-7.7).

CONCLUSION

Evaluating polygenic risk can identify additional venous thromboembolism risk that is not captured in the commonly investigated genes for inherited thrombophilia. Our results indicate that oral contraceptive use is associated with an increased risk for developing a venous thromboembolism, particularly among women with a high genetic predisposition, and that oral contraceptive use dramatically increases the risk thereof short after initiation of use, which decreases with continued use. This suggests that the polygenic risk score could be used to identify women who are at high risk for developing a venous thromboembolism and advise them on alternative methods of contraception.

Genomic risk scores and oral contraceptive-associated ischemic stroke risk: a call for collaboration

Background

Oral contraceptives (OCs) are generally safe but vascular risk factors increase OC-associated ischemic stroke risk. We performed a case-control study to evaluate whether a genomic risk score for ischemic stroke modifies OC-associated ischemic stroke risk.

Methods

The Genetics of Early-Onset Stroke study includes 332 premenopausal women (136 arterial ischemic stroke cases and 196 controls) with data on estrogen-containing OC use within 30 days before the index event (for cases) or interview (for controls). Using a previously validated genetic risk score (metaGRS) for ischemic stroke based on 19 polygenic risk scores for stroke and stroke-associated risk factors, we stratified our combined case-control sample into tertiles of genomic risk. We evaluated the association between OC use and ischemic stroke within each tertile. We tested if the association between OC use and ischemic stroke depended on the genomic risk of stroke using logistic regression with an OC use × metaGRS interaction term. These analyses were performed with and without adjustment for smoking, hypertension, diabetes, coronary heart disease, and body mass index.

Results

After adjustment for vascular risk factors, the odds ratio of OC use was 3.2 (1.7-6.3) overall and increased from the lower, middle, and upper tertile of genomic risk from 1.6 (0.5-5.4) to 2.5 (0.08-8.2) to 13.7 (3.8-67.3) respectively, and a p-value for interaction of 0.001.

Conclusions

Our results suggest that genomic profile may modify the OC-associated ischemic stroke risk. Larger studies are warranted to determine whether a genomic risk score could be clinically useful in reducing OC-associated ischemic stroke.

Combined Oral Contraceptives and Vascular Thrombosis: A Single-Center Experience

Background

Combined oral contraceptives (COCs) are frequently prescribed for contraception, to regulate ovulation and treat endometriosis, and to control menopausal symptoms. A major risk of hormonal contraceptives is vascular thrombosis.

Methods

A retrospective chart review of female patients with deep vein thrombosis (DVT), pulmonary embolism (PE), or other sites of thrombosis or emboli seen in the thrombosis clinic of the department of internal medicine at a tertiary care hospital in Saudi Arabia between March 2010 and February 2015 was performed to identify and characterize which women were taking COCs.

Results

Of 1,008 patients treated for DVT, PE, or other sites of thrombosis or emboli, 100 (9.9%) were taking COCs. Venous (98%) and arterial (2%) thromboses were seen. Overall, 62% of the patients experienced a DVT and 26% pulmonary emboli, and 20% of the patients experienced unusual sites of thrombosis. Furthermore, 53% were obese or morbidly obese. The incidence of venous thrombosis was the highest during the first year of COC use (73%). Of the patients, 8% had thrombophilia.

Conclusion

This study characterizes Saudi women with thrombotic events taking COCs and identifies risk factors, including unusual sites of thrombosis. Most patients experienced the vascular event during the first year of taking COCs. Age of 40-50 years, obesity, and thrombophilia were the commonly observed risk factors.

Asymmetric independence modeling identifies novel gene-environment interactions

Most genetic or environmental factors work together in determining complex disease risk. Detecting gene-environment interactions may allow us to elucidate novel and targetable molecular mechanisms on how environmental exposures modify genetic effects. Unfortunately, standard logistic regression (LR) assumes a convenient mathematical structure for the null hypothesis that however results in both poor detection power and type 1 error, and is also susceptible to missing factor, imperfect surrogate, and disease heterogeneity confounding effects. Here we describe a new baseline framework, the asymmetric independence model (AIM) in case-control studies, and provide mathematical proofs and simulation studies verifying its validity across a wide range of conditions. We show that AIM mathematically preserves the asymmetric nature of maintaining health versus acquiring a disease, unlike LR, and thus is more powerful and robust to detect synergistic interactions. We present examples from four clinically discrete domains where AIM identified interactions that were previously either inconsistent or recognized with less statistical certainty.

Systematic Review of Hormonal Contraception and Risk of Venous Thrombosis

Background

Hormonal contraception (HC) is widely used throughout the world and has been associated with venous thrombosis (VT) such as deep vein thrombosis, pulmonary emboli, and cerebral VT.

Objectives

To provide a current comprehensive overview of the risk of objectively confirmed VT with HC in healthy women compared to nonusers.

Search methods

PubMed was searched from inception to April 2018 for eligible studies in the English language, with hand searching from past systematic reviews.

Selection criteria

We selected original research evaluating risk of objectively confirmed VT in healthy women taking oral or nonoral HC compared with nonusers.

Data collection

The primary outcome of interest was a fatal or nonfatal VT in users of HC compared to nonusers or past users. Studies with at least twenty events were eligible. Adjusted relative risks with 95 percent confidence intervals were reported. Three independent reviewers extracted data from selected studies.

Results

1,962 publications were retrieved through the search strategy, with 15 publications included. Users of oral contraception with levonorgesterol had increased risk of VT by a range of 2.79-4.07, while other oral hormonal preparations increased risk by 4.0-48.6. Levonorgestrel intrauterine devices did not increase risk. Etonogestrel/ethinyl estradiol vaginal rings increased the risk of VT by 6.5. Norelgestromin/ethinyl estradiol patches increased risk of VT by 7.9. Etonogestrel subcutaneous implants by 1.4 and depot-medroxyprogesterone by 3.6. The risk of fatal VT was increased in women aged fifteen to twenty-four by 18.8-fold.

Conclusion

Users of HC have a significant increased risk of VT compared to nonusers. Current risks would project at least 300-400 healthy young women dying yearly in the United States due to HC. Women should be informed of these risks and offered education in fertility-awareness-based methods with comparable efficacy for family planning.

Summary

HC is widely used throughout the world and has been associated with blood clots in the legs and lungs. We searched the literature and found the risks of currently used forms of birth control increased between three- and ninefold for blood clots for healthy women. The risks found would project 300-400 women dying from using HC each year in the United States.

Cerebral venous sinus thrombosis

The cerebral venous system is an unusual site of thrombosis, with a particularly high incidence in young adults. This incidence has increased in past decades because of the improvement of neuroradiological techniques. Risk factors for cerebral venous sinus thrombosis overlap with those of other venous thromboembolism sites; however, some are specific for this particular anatomical district. Prognosis is favorable in most cases if diagnosis is made rapidly and treatment is promptly initiated, even if acute complications or chronic invalidity still occur in a quarter of patients. The mainstay of treatment is anticoagulation, which is necessary in order to block clot propagation and obtain recanalization. Intracranial bleeding does not contraindicate anticoagulation. Endovascular procedures are reserved for patients with a particularly severe presentation or rapidly declining neurological symptoms despite appropriate anticoagulation, although data from clinical trials are lacking. Specifically, this review addresses the epidemiology, clinical presentation and course, risk factors, and treatment of cerebral venous sinus thrombosis, with a special focus on the pediatric population.

Oral Contraceptives and HRT Risk of Thrombosis

Estrogen-containing medication, prescribed either for contraception in women of reproductive age or for prevention of cardiovascular events and osteoporosis as well as for alleviation of symptoms related to menopause, is associated with changes in the hemostatic balance and contributes to increased risk of development of venous thromboembolic complications. This risk is dose and medication dependent, increases with age, congenital and/or acquired predisposition to thrombosis, and mode of administration. This review attempts to summarize the current knowledge regarding the pathophysiology of oral contraceptive (OC) and hormone replacement therapy (HRT) -induced prothrombotic state in women, the risk of thrombosis associated with administration of various commercially available OCs and HRT, the additional risk in women with hereditary or acquired thrombophilia, and the currently available recommendations regarding massive screening of women for thrombophilia prior to initial prescription or continuation of treatment with OCs and HRT preparations.

Combined hormonal contraception and the risk of venous thromboembolism: a guideline

While venous thromboembolism (VTE) is rare in young women of reproductive age, combined oral contraceptives increase the risk of VTE. In the patient in whom combined hormonal contraception is appropriate, it is reasonable to use any currently available preparation.

Environmental and Genetic Risk Factors Associated with Venous Thromboembolism

Venous thromboembolism (VTE) includes deep vein thrombosis and pulmonary embolism, and a combination of environmental and genetic risk factors contributes to VTE risk. Within environmental risk factors, some are provoking (e.g., cancer, surgery, trauma or fracture, immobilization, pregnancy and the postpartum period, long-distance travel, hospitalization, catheterization, and acute infection) and others are nonprovoking (e.g., age, sex, race/ethnicity, body mass index and obesity, oral contraceptive or hormone therapy use, corticosteroid use, statin use, diet, physical activity, sedentary time, and air pollution). Additionally, VTE has a strong genetic basis, with approximately 50 to 60% of the variance in VTE incidence attributed to genetic effects. Some genetic susceptibility variants that contribute to risk have been identified in candidate genes, mostly related to the clotting system and responsible for inherited hypercoagulable states (e.g., factor V Leiden, prothrombin, fibrinogen gamma, or blood group non-O). Other susceptibility single-nucleotide polymorphisms have been identified from genome-wide association studies, such as the two new loci in TSPAN15 (rs78707713) and SCL44A2 (rs2288904) genes. Risk factors are not always associated with VTE in isolation; however, and an understanding of how environmental and genetic factors interact may provide insight into the pathophysiology of VTE, possibly identifying opportunities for targeted prevention and treatment.

A Review of Hormonal Contraception and Venous Thromboembolism in Adolescents

BACKGROUND

The number of adolescents who are prescribed hormonal contraception (HC) for contraceptive and noncontraceptive indications is increasing. Approximately 1 of 4 female adolescents will use some form of HC by age 19 years. Venous thromboembolism (VTE) is a rare, but life-threatening complication associated with HC use. Although adolescents aged 15 to 19 years have the lowest absolute HC-associated VTE risk, they still account for 5.9% of HC-associated VTE. The absolute HC-associated VTE risk for those younger than 15 years of age is not well described.

OBJECTIVE

The objectives of this report are to describe the current literature regarding HC-associated VTE in adolescents, to review the coagulation cascade and in vivo coagulation, to highlight differences between the adolescent and adult coagulation profiles, to discuss coagulation profile changes related to HC use, and to identify knowledge deficits for future study.

CONCLUSION

The mechanisms and confounding variables that lead to HC-associated VTE in all adolescents are not well understood because many large HC studies exclude female adolescents younger than 18 years of age. Because of the paucity of data in this age group, observational studies and randomized controlled trials of VTE risk in adolescents on varying forms of HC are needed. Studies should include female adolescents across the entire adolescent age span (12-21 years) to better understand HC-associated VTE risk in this population.

Combined oral contraceptives, thrombophilia and the risk of venous thromboembolism: a systematic review and meta-analysis

Essentials We performed a meta-analysis on thrombosis risk in thrombophilic oral contraceptive (COC)-users. The results support discouraging COC-use in women with a natural anticoagulant deficiency. Contrary, additive risk of factor V Leiden (FVL) or prothrombin-G20210A (PT) mutation is modest. Women with a FVL/PT-mutation as single risk factor can use COCs if alternatives are not tolerated.

SUMMARY

Background Combined oral contraceptives (COCs) are associated with an increased risk of venous thromboembolism (VTE), which is shown to be more pronounced in women with hereditary thrombophilia. Currently, WHO recommendations state that COC-use in women with hereditary thrombophilias (antithrombin deficiency, protein C deficiency, protein S deficiency, factor V Leiden and prothrombin-G20210A mutation) is associated with an unacceptable health risk. Objective To perform a meta-analysis evaluating the additional risk of VTE in COC-users with thrombophilia. Methods The MEDLINE and EMBASE databases were searched on 10 February 2015 for potential eligible studies. A distinction was made between 'mild' (factor V Leiden and prothrombin-G20210A mutation) and 'severe' thrombophilia (antithrombin deficiency, protein C deficiency, protein S deficiency, double heterozygosity or homozygosity of factor V Leiden and prothrombin-G20210A mutation). Results We identified 12 case-control and three cohort studies. In COC-users, mild and severe thrombophilia increased the risk of VTE almost 6-fold (rate ratio [RR], 5.89; 95% confidence interval [CI], 4.21-8.23) and 7-fold (RR, 7.15; 95% CI, 2.93-17.45), respectively. The cohort studies showed that absolute VTE risk was far higher in COC-users with severe thrombophilia than in those with mild thrombophilia (4.3 to 4.6 vs. 0.49 to 2.0 per 100 pill-years, respectively), and these differences in absolute risks were also noted in non-affected women (0.48 to 0.7 vs. 0.19 to 0.0), but with the caveat that absolute risks were estimated in relatives of thrombophilic patients with VTE (i.e. with a positive family history). Conclusion These results support discouraging COC-use in women with severe hereditary thrombophilia. By contrast, additive VTE risk of mild thrombophilia is modest. When no other risk factors are present, (e.g. family history) COCs can be offered to these women when reliable alternative contraceptives are not tolerated.

Family history of venous thromboembolism is a risk factor for venous thromboembolism in combined oral contraceptive users: a nationwide case-control study

BACKGROUND

The aim was to assess the risk of venous thromboembolism (VTE) associated with use of combined oral contraceptives (COCs) in women with a family history of VTE.

METHODS

The study is a Swedish nationwide case-control study based on the Multigeneration register, the Swedish Hospital Discharge Register, the Outpatient Care Register, and the Swedish Prescribed Drug Register. Cases (n = 2,311) were non-pregnant Swedish women aged 15-49 with first VTE diagnoses between January 2006 and December 2010. Five controls without VTE were matched to each case on age and education level. Conditional logistic regression examined the associations with VTE with determination of odds ratio (OR) for first VTE diagnosis. Effect modification was assessed by interaction testing.

RESULTS

Both among controls (14.6 % vs. 4.5 %; p < 0.0001) and cases (27.2 % vs. 8.8 %; p < 0.0001) COC use was more common in women without a family history of VTE compared with women with a family history of VTE. In a multivariate conditional logistic regression model the OR for VTE was 2.53 (95 % CI 2.23-2.87) for COC users and 2.38 (2.09-2.71) for individuals with a family history of VTE. The OR for VTE for COC users with a family history of VTE was 6.02 (5.02-7.22). There was no significant interaction between family history of VTE and COC use (OR 0.92, 0.57-1.46).

CONCLUSIONS

Family history of VTE is a risk factor for VTE in women using COCs. The low prevalence of COC use among women with a family history of VTE suggests that family history of VTE is considered when COCs are prescribed in Sweden. The present study may therefore even underestimate the importance of family history of VTE. The lack of interaction indicates that the risk of COC use in women with family history of VTE is determined by the product of the ORs for family history and COC use.

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.

Overview and assessment of risk factors for pulmonary embolism

Pulmonary embolism is one of the most common undiagnosed conditions affecting hospitalized patients. There are a plethora of risk factors for venous thromboembolism and pulmonary emboli. These factors are grouped under the broad triad of hypercoagulability, stasis and injury to provide a framework for understanding. Important risk factors include inherited thrombophilia, age, malignancy and estrogens. These risk factors are reviewed in detail and several risk assessment models are reviewed. These risk assessment models help identify those at risk for disease and therefore candidates for thromboprophylaxis. Diagnosis can be difficult and is aided by clinical decision rules that incorporate clinical scores that define the likelihood of pulmonary embolism. These are important considerations, not only for diagnostic purposes, but also to minimize excessive use of imaging, which increases exposure to and risks associated with radiation. A healthy index of suspicion is often the key to diagnosis.

Different combined oral contraceptives and the risk of venous thrombosis: systematic review and network meta-analysis

OBJECTIVE

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

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

PubMed, Embase, Web of Science, Cochrane, Cumulative Index to Nursing and Allied Health Literature, Academic Search Premier, and ScienceDirect up to 22 April 2013.

REVIEW METHODS

Observational studies that assessed the effect of combined oral contraceptives on venous thrombosis in healthy women. 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. The requirement for crude numbers did not allow adjustment for potential confounding variables.

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 1.9 and 3.7 per 10,000 woman years, in line with previously reported incidences of 1-6 per 10,000 woman 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.

CONCLUSION

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.

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.

Oral contraceptives and venous thromboembolism: a systematic review and meta-analysis

BACKGROUND

An association between oral contraceptive (OC) use and venous thromboembolism (VTE) has long been recognized. However, no summary estimates of the increase in VTE risk associated with OC use have been available since 1995, and no meta-analyses have evaluated the VTE risk of new preparations containing drospirenone.

OBJECTIVE

The aim of the study was to carry out a meta-analysis to summarize existing evidence on the association between venous VTE and OC use, and to investigate how such an association may vary according to the type of OC, OC user characteristics, study characteristics and biases.

METHODS

Relevant cohort or case-control studies were searched in MEDLINE and other electronic databases up to May 2010, with no language restriction. Data were combined using a generic inverse-variance approach. Meta-regression in addition to stratification was used to explore potential predictors of the summary estimate of risk.

RESULTS

Sixteen cohort and 39 case-control studies were included in at least one comparison. Overall, the odds ratio (OR) of OC users versus non-users was 3.41 (95% CI 2.98, 3.92). This estimate was based upon nine cohort studies evaluating approximately 12 000 000 person-years, and 23 case-control studies including approximately 45 000 women. VTE risk for OC users was significantly lower in studies evaluating 'all VTE cases' than in those evaluating 'idiopathic VTE only' (OR 3.09 and 4.94, respectively). Among the carriers of genetic mutations G20210A and Factor V Leiden (FVL), OC users showed a significantly increased VTE risk compared with non-users (OR 1.63; 95% CI 1.01, 2.65, and OR 1.80; 95% CI 1.20, 2.71, respectively). When the newest OCs containing drospirenone were compared with non-drospirenone-containing OCs (except those containing levonorgestrel only), VTE risk did not significantly increase (OR 1.13; 95% CI 0.94, 1.35).

CONCLUSIONS

This meta-analysis confirms that OC use significantly increases VTE risk. The strength of this association, however, varies according to the generation of OC, type of outcome and presence of a genetic mutation, with ORs ranging from 3 to 5.

Increased risk of stroke in oral contraceptive users carried replicated genetic variants: a population-based case-control study in China

Combined oral contraceptives (COC) use is a unique risk factor for stroke in women, and may modify the associations between genetic polymorphisms and stroke. To investigate whether the genetic variants identified in a recent genome-wide association study (GWAS) could be replicated in Chinese women, as well as, whether related risk was different in COC users, 451 stroke cases and 831 age- and region-matched controls were recruited from our cohort. Genotyping of 3 SNPs (rs700651, rs10958409, and rs1333040) was performed by the polymerase chain reaction assay with TaqMan probes. The history of contraceptive use and relevant information were obtained from a face-to-face interview. Odds ratios (OR) with 95 % confidence interval (CI) were estimated under conditional logistic regression model after adjustment for cardiovascular covariates. Our study replicated the associations of rs10958409 and rs1333040, with the risk of stroke, especially hemorrhagic subtype, but failed to confirm association of rs700651. COC use was associated with a 1.56-fold (OR 1.56, 95 % CI 1.21-2.01) increased risk of stroke. COC users with rs10958409 GA/AA or rs1333040 CT/TT genotypes had an increased risk of overall stroke by 1.59-fold (OR 2.59, 95 % CI 1.59-4.19) and 3.24-fold (OR 4.24, 95 % CI 1.71-10.49), respectively, compared with the non-users with wild-type genotypes. Moreover, the risk of hemorrhagic stroke increased by 4.81- and 15.06-fold when risk allele carriers of rs10958409 or rs1333040 who took COC. Our results confirmed the associations of two GWAS SNPs, also suggested combination effects of these genetic variants and COC use on stroke risk.

Thrombophilic screening in Turner syndrome

AIM

The aim of this study was to determine, in patients with Turner syndrome (TS), the prevalence of thrombophilic disorders correlating with a higher risk of venous thromboembolism (VTE), to evaluate if thrombophilia is associated with the genetic features of these patients and whether screening before hormone replacement therapy (HRT) is advisable.

PATIENTS AND METHODS

We examined 82 TS patients. In all patients we analyzed activated factor VIII:C, fibrinogen, antithrombin (AT), protein C (PC), protein S (PS), activated PC resistance, and homocysteine. For every patient, an investigation for mutations in prothrombin G20210A, factor V R506Q, methylenetetrahydropholate reductase (MTHFR) C 677T and A1298C was conducted.

RESULTS

Low values of PC in 3 patients (3.70%), low values of PS in 12 (14.81%), and hyperhomocysteinemia in 4 (4.87%) were found; 52 girls (64.2%) presented hyperfibrinogenemia. Three patients were heterozygous for the prothrombin G20210A allele mutation (3.66%) and the factor V mutation was present in 4 patients (4.88%). No TS patient had a homozygous mutation. Mutations in the MTHFR gene were present in 62 girls, in 17 patients (20.7%) they were homozygous and in 45 patients (54.88%) heterozygous.

CONCLUSIONS

Considering the increased risks with the association between VTE and the higher prevalence of PC and PS deficiencies, TT genotype mutations and high level of fibrinogen, it is advisable to perform a complete thrombophilia screening in TS patients before starting HRT.

Thrombotic risk during oral contraceptive use and pregnancy in women with factor V Leiden or prothrombin mutation: a rational approach to contraception

Current guidelines discourage combined oral contraceptive (COC) use in women with hereditary thrombophilic defects. However, qualifying all hereditary thrombophilic defects as similarly strong risk factors might be questioned. Recent studies indicate the risk of venous thromboembolism (VTE) of a factor V Leiden mutation as considerably lower than a deficiency of protein C, protein S, or antithrombin. In a retrospective family cohort, the VTE risk during COC use and pregnancy (including postpartum) was assessed in 798 female relatives with or without a heterozygous, double heterozygous, or homozygous factor V Leiden or prothrombin G20210A mutation. Overall, absolute VTE risk in women with no, single, or combined defects was 0.13 (95% confidence interval 0.08-0.21), 0.35 (0.22-0.53), and 0.94 (0.47-1.67) per 100 person-years, while these were 0.19 (0.07-0.41), 0.49 (0.18-1.07), and 0.86 (0.10-3.11) during COC use, and 0.73 (0.30-1.51), 1.97 (0.94-3.63), and 7.65 (3.08-15.76) during pregnancy. COC use and pregnancy were independent risk factors for VTE, with highest risk during pregnancy postpartum, as demonstrated by adjusted hazard ratios of 16.0 (8.0-32.2) versus 2.2 (1.1-4.0) during COC use. Rather than strictly contraindicating COC use, we advocate that detailed counseling on all contraceptive options, including COCs, addressing the associated risks of both VTE and unintended pregnancy, enabling these women to make an informed choice.

Ambient particulate matter air pollution and venous thromboembolism in the Women's Health Initiative Hormone Therapy trials

BACKGROUND

The putative effects of postmenopausal hormone therapy on the association between particulate matter (PM) air pollution and venous thromboembolism (VTE) have not been assessed in a randomized trial of hormone therapy, despite its widespread use among postmenopausal women.

OBJECTIVE

In this study, we examined whether hormone therapy modifies the association of PM with VTE risk.

METHODS

Postmenopausal women 50-79 years of age (n = 26,450) who did not have a history of VTE and who were not taking anticoagulants were enrolled in the Women's Health Initiative Hormone Therapy trials at 40 geographically diverse U.S. clinical centers. The women were randomized to treatment with estrogen versus placebo (E trial) or to estrogen plus progestin versus placebo (E + P trial). We used age-stratified Cox proportional hazard models to examine the association between time to incident, centrally adjudicated VTE, and daily mean PM concentrations spatially interpolated at geocoded addresses of the participants and averaged over 1, 7, 30, and 365 days.

RESULTS

During the follow-up period (mean, 7.7 years), 508 participants (2.0%) had VTEs at a rate of 2.6 events per 1,000 person-years. Unadjusted and covariate-adjusted VTE risk was not associated with concentrations of PM < 2.5 µm (PM(2.5)) or < 10 µm (PM(10))] in aerodynamic diameter and PM × active treatment interactions were not statistically significant (p > 0.05) regardless of PM averaging period, either before or after combining data from both trials [e.g., combined trial-adjusted hazard ratios (95% confidence intervals) per 10 µg/m(3) increase in annual mean PM(2.5) and PM(10), were 0.93 (0.54-1.60) and 1.05 (0.72-1.53), respectively]. Findings were insensitive to alternative exposure metrics, outcome definitions, time scales, analytic methods, and censoring dates.

CONCLUSIONS

In contrast to prior research, our findings provide little evidence of an association between short-term or long-term PM exposure and VTE, or clinically important modification by randomized exposure to exogenous estrogens among postmenopausal women.

Hormonal contraception and thrombotic risk: a multidisciplinary approach

Heightened publicity about hormonal contraception and thrombosis risk and the publication of new guidelines by the World Health Organization in 2009 and the Centers for Disease Control and Prevention in 2010 addressing this complex issue have led to multidisciplinary discussions on the special issues of adolescents cared for at our pediatric hospital. In this review of the literature and new guidelines, we have outlined our approach to the complex patients referred to our center. The relative risk of thrombosis on combined oral contraception is three- to fivefold, whereas the absolute risk for a healthy adolescent on this therapy is only 0.05% per year. This thrombotic risk is affected by estrogen dose, type of progestin, mechanism of delivery, and length of therapy. Oral progestin-only contraceptives and transdermal estradiol used for hormone replacement carry minimal or no thrombotic risk. Transdermal, vaginal, or intrauterine contraceptives and injectable progestins need further study. A personal history of thrombosis, persistent or inherited thrombophilia, and numerous lifestyle choices also influence thrombotic risk. In this summary of one hospital's approach to hormone therapies and thrombosis risk, we review relative-risk data and discuss the application of absolute risk to individual patient counseling. We outline our approach to challenging patients with a history of thrombosis, known thrombophilia, current anticoagulation, or family history of thrombosis or thrombophilia. Our multidisciplinary group has found that knowledge of the guidelines and individualized management plans have been particularly useful for informing discussions about hormonal and nonhormonal options across varied indications.

The risk of venous thrombosis, including cerebral vein thrombosis, among women with thrombophilia and oral contraceptive use: a meta-analysis

Several small studies have reported an elevated risk of venous thrombosis (VT) with thrombophilia and oral contraceptive (OCP) use. We aimed to summarize the risk of VT among women with thrombophilia and OCP use and to assess the interaction between the 2 factors. We selected 15 studies that assessed the prevalence of OCP use and thrombophilia among reproductive-aged women. Odds ratios (ORs) were calculated for each study and pooled using the random effects model. We found an increased risk of VT among women with OCP use (pooled OR 3.0, 95% confidence interval [CI] 1.9-4.5) and with thrombophilia (pooled OR 4.5, CI 3.4-5.9), respectively. Heterogeneity was significant (I (2) >80%). Women with both thrombophilia and OCP use had a 14-fold risk of VT compared to healthy OCP nonusers (pooled OR 14.25, CI 6.2-32.8). Oral contraceptive use and thrombophilia similarly increase VT risk. Our study confirms an interaction between OCP use and thrombophilia.

The effect of prothrombotic blood abnormalities on risk of deep vein thrombosis in users of hormone replacement therapy: a prospective case-control study

BACKGROUND

Few studies have assessed the effect of prothrombotic blood abnormalities on the risk of deep vein thrombosis (DVT) with hormone replacement therapy (HRT).

METHODS

We studied postmenopausal women with suspected DVT in whom HRT use and prothrombotic blood abnormalities were sought. Cases had unprovoked DVT and controls had no DVT and without DVT risk factors. The risk of DVT was determined in women with and without prothrombotic abnormalities.

RESULTS

A total of 510 postmenopausal women with suspected DVT were assessed; 57 cases and 283 controls were identified. Compared to HRT, nonusers without the factor V Leiden mutation, the risk of DVT was increased in estrogen-progestin HRT users (odds ratio [OR], 3.2; 95% confidence interval [CI]: 1.2-8.6) and in nonusers with the factor V Leiden mutation (OR, 5.3; 1.9-15.4) and appears multiplied in users of estrogen-progestin HRT with the factor V Leiden mutation (OR, 17.1; 3.7-78). Compared to HRT, nonusers with normal factor VIII, the risk of DVT was increased in estrogen-progestin HRT users with normal factor VIII (OR, 2.8; 1.0-7.9) and in HRT nonusers with the highest factor VIII quartile (OR, 6.0; 2.1-17), and appears to be multiplied in women who are users of estrogen-progestin HRT with the highest factor VIII quartile (OR, 17.0; 3.6-80).

CONCLUSIONS

In postmenopausal women who are estrogen-progestin HRT users, the presence of the factor V Leiden mutation or an elevated factor VIII level appears to have a multiplicative effect on their overall risk of DVT, increasing it 17-fold compared to women without these blood abnormalities who are HRT nonusers.

Thrombophilia screening--at the right time, for the right patient, with a good reason

Thrombophilia can be identified in about half of all patients presenting with venous thromboembolism (VTE). Thrombophilia screening for various indications has increased tremendously, but whether the results of such tests help in the clinical management of patients is uncertain. Here, current recommendations for thrombophilia screening in selected groups of patients, and considerations whether other high-risk subjects should be tested are reviewed. The methods for determination of the most common thrombophilic defects (antithrombin, protein C, protein S deficiencies, Factor V Leiden and prothrombin G20210A) associated with strong to moderate risk of VTE are described, indicating the timing and location of thrombophilia screening. Circumstances when a positive result of thrombophilia screening helps clinicians decide if adjustments of the anticoagulant regime are needed are discussed. Finally, psychological, social and ethical dilemmas associated with thrombophilia screening are indicated.

Venous thromboembolism in young female while on oral contraceptives: high frequency of inherited thrombophilia and analysis of thrombotic events in 400 czech women

Oral contraceptive use is a common risk factor for venous thromboembolism in women of reproductive age. The presence of inherited thrombophilia further increases this risk.

METHODS

We analyzed a large group of 400 Czech women with venous thromboembolism in association with oral contraceptive with regard to duration of use at the time of manifestation of venous thromboembolism, the frequency of inherited and acquired thrombophilia, the frequency of eliciting risk factor for thrombosis including immobilization, surgery, administration of plaster cast, long travel, and so on, and the type of thrombosis. The mean age of the women was 26 years, and the average duration of use was 45 months at the onset of thrombosis.

RESULTS

Venous thrombosis solely due to the pill occurred in 57% of the women, and in the other 43%, an additional transient eliciting factor was recognized. Among the clinical manifestation, distal thrombosis prevailed (N = 231, 58%) followed by proximal deep vein thrombosis (N = 65, 16%), pulmonary embolism (N = 21, 5%), and thrombosis in unusual sites (N = 20, 5%). Inherited or acquired thrombophilia was diagnosed in 195 (49%) women: factor V Leiden mutation in 35%, congenital deficiency of antithrombin in 1.8%, protein C in 0.8%, protein S in 1%, F IIG20210A in 5%, and antiphospholipid syndrome (APS) in 5.3%. Among the most common risk factors were immobilization of lower limb, minor and major surgery, and trauma.

CONCLUSION

The results confirm that venous thromboembolism is a multifactorial disease in which thrombophilia screening is needed in young symptomatic women on the pill with thrombosis. The results also emphasize the value of proper thromboprophylaxis in women while on oral contraceptive in situations of increased risk for venous thromboembolism.

Venous thromboembolism in women

Abstract

The risk of venous thromboembolism (VTE) varies throughout a woman’s life and is associated primarily with underlying hormonal exposure. Alteration in hemostatic mechanisms, including resistance to activated protein C, may explain this altered risk. Initially, development of VTE with the use of contraception in young adulthood may reveal inherited thrombophilia. Pregnancy, and particularly the post-partum period, likely confer the greatest risk of VTE, but the absolute risk is small. Guidelines for prevention of VTE during pregnancy are based on personal or family history of VTE, and known inherited thrombophilia. Use of hormone replacement therapy later in life is associated with increased risk of VTE, and may be safest if given as an estrogen-only preparation to young postmenopausal women for less than 5 years. Universal screening for thrombophilia prior to pregnancy or initiating hormonal therapy is not recommended; however, selected testing in high-risk groups may be warranted. The lack of firm recommendations for the prevention of VTE in women highlights the need for future investigation aimed at identifying high-risk groups and evaluating the efficacy of prophylactic measures.

Hormone therapy and thromboembolic disease

PURPOSE OF REVIEW

Hormone therapy increases the risk of venous thromboembolism (VTE). To reduce this risk, changes in dosage, composition and route of administration have been made over the years. This review provides a summary of the available evidence and an update on the most recent findings on the issue.

RECENT FINDINGS

Contraceptives containing third-generation progestagens confer a higher risk of VTE than second-generation compounds. Little data are available on preparations containing less than 30 micarog of estrogen, new progestagens or levonorgestrel-releasing intrauterine devices. Hormone replacement therapy increases the risk of VTE by 2 to 3-fold. Transdermal administration may be less thrombogenic than oral administration, while different estrogens and progestagens may carry a different risk. VTE risk is further increased in carriers of inherited thrombophilia. Despite a similar increase in relative risk of thrombosis associated with hormone therapy, absolute risk is lower in fertile women and higher in postmenopausal ones. Universal screening for thrombophilia before prescribing hormone replacement therapy might be cost-effective.

SUMMARY

Careful evaluation of individual risk factor is warranted before prescribing hormone therapy. Further investigations are needed to establish whether or not newer compounds are safer than older ones with respect to the risk of thrombosis.

Upper extremity deep vein thrombosis after suspension of progesterone-only oral treatment

The intake of steroid hormone contraceptives is a strong and independent risk factor for venous thromboembolism. Several studies have assessed an increased risk of venous thromboembolism in women using oral contraceptives who are carriers of the G20210A mutation in the prothrombin gene. Most trials evaluating the thrombotic risk of oral contraceptives are based on combined oral preparations, but only a few focus on progestogen-only oral preparations. Results from such studies are conflicting and globally assess the thrombotic risk, ranging from modest to slightly increased. Furthermore, little is known about the relationship between the C677T mutation in the methylenetetrahydrofolate reductase gene and the progestogen-based preparations. Herewith we report the case of a 49-year-old woman with a complex genetic thrombosis risk factor who had taken oral progesterone for 15 months without any complication, but then experienced severe left upper extremity deep vein thrombosis 2 months after the drug suspension.

Sex hormones and thrombosis

There is compelling evidence that use of oral formulations of female hormone replacement and of the combined oral contraceptive induces a prothrombotic state. This translates to an increased thrombotic risk. Within the individual, the absolute risk is determined by the interaction between that induced by hormone use and heritable and acquired risk factors for thrombosis. Knowledge of the accumulating epidemiologic and clinical trial-derived data on this topic is essential for the delivery of evidence-based counseling in the clinical environment and is the subject of this review.

Inherited Thrombophilia: Key Points for Genetic Counseling

With the evolution of medical genetics to focus on highly prevalent, multifactorial conditions, it is inevitable that genetic counselors will be called upon to participate in the evaluation and counseling of individuals with inherited thrombophilia. The purpose of this review is to educate the genetic counselor on key issues related to risk assessment and genetic counseling for hereditary thrombophilia. The information contained in this document is derived from an extensive review of the literature, as well as the author's personal expertise. Upon completion of this review, the genetic counselor will be able to: a) describe inherited and acquired risk factors for thrombosis, b) collect and interpret personal and family histories to assess risk related to hereditary thrombophilia, c) discuss the potential advantages and disadvantages of thrombophilia testing, including psychosocial aspects and implications for medical management, and d) identify educational and support resources for patients and families.

The endogenous thrombin potential and the risk of venous thromboembolism

BACKGROUND

The risk of venous thromboembolism (VTE) is increased by an excess of procoagulant or by a defect of anticoagulant proteins, with circumstantial risk factors playing a significant contribution. These conditions are directly linked to or are compatible with increased thrombin generation. Assuming that the more thrombin is generated the higher is the risk of VTE, an overall coagulation test monitoring ex vivo thrombin generation and reflecting the interaction of pro- and anticoagulant proteins would be useful to determine the risk of VTE.

PATIENTS AND METHODS

This hypothesis was tested by measuring the endogenous thrombin potential (ETP) without or with thrombomodulin (TM) in plasmas from 403 individuals stratified according to their relative risk of VTE (no, low, intermediate, or high risk) according to whether or not they had congenital and/or circumstantial risk factors. Odds ratio (OR) and 95% confidence interval (CI), taken as a measure of the relative risk of having high levels of ETP, were calculated for the different categories relatively to the no-risk category.

RESULTS

When the ETP was measured with TM, ORs (95% CI) were 2.10 (1.23-3.60); 4.03 (2.18-7.45) and 4.96 (2.40-10.23) for the low-, intermediate and high-risk category. When ETP was measured without TM there was no gradient of OR values as function of the risk category.

CONCLUSIONS

ETP measured with TM may help to distinguish individuals with different risk of VTE, however, the practical utility of measuring ETP in clinical practice remains to be evaluated in prospective studies.

Hormonal contraception: recent advances and controversies

This document will outline new delivery systems and contraceptive formulations, summarize recent advances in emergency contraception, and review the effects of hormonal contraception on cancer risks, cardiovascular disease, and bone.

Phenotypic Heterogeneity in Patients with Homozygous Prothrombin 20210AA Genotype. A paper from the 2005 William Beaumont Hospital Symposium on Molecular Pathology

Venous thromboembolic events (VTEs) affect an estimated 1 in 1000 people annually, resulting in approximately 50,000 deaths, with prevalence increasing with age. The genetic contributors to thrombosis have been described and further explored within the last 15 years as molecular diagnostic techniques have become more widely used. The prothrombin G20210A mutation is the second most common inherited thrombotic risk factor after factor V Leiden. Generally present in less than 5% of the population, the mutation's prevalence varies greatly with ethnicity. The G20210A mutation confers a mildly increased thrombotic risk that is compounded by the presence of other risk factors. One striking characteristic of the G20210A mutation is the phenotypic heterogeneity of the rare homozygous cases. Forty percent of the reported homozygous cases are asymptomatic. Many of the symptomatic patients have additional risk factors that might compound the thrombotic risk. We present here a review of the literature for the homozygous prothrombin G20210A mutation and describe additional cases that exemplify the heterogeneous nature of this entity.

Exogenous Sex Hormones and Thrombophilia

Worldwide, hundreds of millions of women use exogenous estrogens in contraceptives or for postmenopausal hormone replacement. Exogenous estrogens increase the risk for venous and arterial thrombosis. This article reviews the use of exogenous sex hormones in women with thrombophilia.

Estrogen-based hormone therapy and thrombosis risk in women with essential thrombocythemia

BACKGROUND

There is currently insufficient evidence to either support or refute an association between estrogen-based hormone treatment (EBHT) and thrombosis risk in essential thrombocythemia (ET).

METHODS

A retrospective review of thrombotic events, which occurred both at diagnosis of ET and during subsequent follow-up, was performed in a consecutive cohort of women with WHO-defined ET seen at the Mayo Clinic. Details of EBHT were concomitantly obtained.

RESULTS

A total of 305 women were seen during the study period and followed for a median of 133 months. EBHT at diagnosis was documented in 59 women and such therapy was instituted at a variable time after diagnosis in 34 additional patients. At diagnosis, major thrombosis occurred in 73 patients (24%), including 11 of 59 (19%) on EBHT and 62 of 246 (25%) not on EBHT (P=.28). Thrombosis after diagnosis occurred in 94 patients (31%), including 64 of 212 (30%) not on EBHT, 5 of 17 (29%) in whom EBHT was discontinued at diagnosis, 13 of 42 (31%) in whom EBHT was continued despite the diagnosis of ET, and 12 of 34 (35%) in whom EBHT was started after diagnosis (P=.95). The overall results were the same when arterial and venous events were analyzed separately. However, EBHT in the form of oral contraceptives (OCP) was associated with an increased risk of venous thrombosis (P=.03).

CONCLUSIONS

EBHT is safe in ET outside the setting of OCP use, which might be associated with an increased risk of deep vein thrombosis.

Hypercoagulability markers in young asymptomatic heterozygous carriers of factor V Leiden (G1691A) or prothrombin (G20210A) variant

BACKGROUND

Mutations in factor V (factor V Leiden-G1691A) and prothrombin (G20210A) genes are important risk factors for thrombophilia due to their high incidence in patients with thromboembolic events, especially among the young. However, it is not clear if levels of hypercoagulability markers are significantly altered in asymptomatic young carriers of factor V Leiden or prothrombin G20210A.

METHODS

Hemostatic status of 32 asymptomatic young individuals carrying these mutations and of 18 normal control individuals was investigated through the determination of plasma thrombomodulin (TM), prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT) and D-dimer.

RESULTS

No significant differences were observed in these hemostatic markers when comparing groups of individuals carrying mutations and the control group.

CONCLUSION

Analysis of these results leads to the conclusion that the presence of these mutations, in the absence of acquired risk factors, does not constantly predispose these young carriers to a state of hypercoagulability.

Does use of hormonal contraceptives among women with thrombogenic mutations increase their risk of venous thromboembolism? A systematic review

Because use of combined oral contraceptives (COCs) confers some risk of venous thromboembolism (VTE), there is concern that this effect may be greater among women with thrombogenic mutations. We searched the MEDLINE and EMBASE databases for all articles published from January 1966 through September 2004 for evidence relevant to hormonal contraception and thrombogenic mutations. Of 301 articles identified by the search strategy, 16 evaluated COCs, and no studies were found for other hormonal methods. We used standard abstract forms and grading systems to summarize and assess the quality of the evidence. A total of 10 studies together provided "good" evidence of a greater risk of VTE (risk ratios of 1.3-25.1) and cerebral vein or cerebral sinus thrombosis among COC users with factor V Leiden mutation when compared with nonusers who have the mutation. The evidence for prothrombin and other thrombogenic mutations was not as strong as for factor V Leiden mutation. It is unclear whether the type of COC or duration of use modifies the risk of VTE among women with thrombogenic mutations.

Comparison of incidence/risk of venous thromboembolism (VTE) among selected clinical and hereditary risk markers: a community-based cohort study

Background

Little information is available from community-based long-term VTE cohort studies to compare the absolute thrombosis risk of established clinical and genetic risk factors.

Materials and methods

The occurrence of venous thromboembolism (VTE) was observed during a 10-year observation period in the BAvarian ThromboEmbolic Risk (BATER) study, a cohort study of 4337 women (age 18–55 years). We collected data on demographics, reproductive life, lifestyle, conditions/diseases, and particularly potential risk factors for VTE with a self-administered questionnaire. The objective was to present incidence rates of VTE and to show relative risk estimated associated with different clinical and genetic risk factors.

Results

34 new, by diagnostic means confirmed VTE events occurred during the observation time of 32,656 women-years (WY). The overall incidence of VTE was 10.4 per 10⁴ WY. The incidence rates varied markedly among different risk cohorts. The highest incidence was observed in women with previous history of VTE, followed by family history of VTE. None of the measured "genetically-related risk markers" (antithrombin, protein C, FVL, prothrombin mutation, or MTHFR) showed a significant VTE risk.

Conclusion

Most of the discussed VTE risk factors showed no significant association with the occurrence of new VTEs due to smallness of numbers. Only first-degree family history of VTE and own history of a previous VTE event depicted a significant association with future VTE. Clinical information seems to be more important to determine future VTE risk than genetically related laboratory tests.

Prothrombotic conditions, oral contraceptives, and the risk of ischemic stroke

BACKGROUND

The role of inherited prothrombotic conditions, including factor V Leiden (FV G1691A), prothrombin G20210A, and the methylenetetrahydrofolate reductase (MTHFR) C677T genotype, in the pathogenesis of ischemic stroke is not well established. The effects of these factors may be potentiated by the use of oral contraceptives, analogous to observations in venous thrombosis.

METHODS

Patients (n = 193) were women aged 20-49 years with ischemic stroke. Controls (n = 767) were women without arterial thrombosis stratified for age, calendar year of the index event, and residence. The relative risk of ischemic stroke was estimated with unconditional logistic regression, adjusted for stratification variables.

FINDINGS

Factor V Leiden and MTHFR 677TT were more common in patients than in controls [odds ratio (OR): 1.8; 95% confidence interval (CI): 0.9-3.6 respectively OR: 1.5; 95% CI: 0.9-2.6]. The frequency of prothrombin G20210A was similar in cases and controls. Carriers of FV Leiden using oral contraceptives had a 11.2-fold (95% CI: 4.3-29.0) higher risk of ischemic stroke than women without either risk factor. Women with MTHFR 677TT using oral contraceptives had a 5.4-fold (95% CI: 2.4-12.0) higher risk than women without these risk factors.

INTERPRETATION

These data suggest that carriers of FV Leiden or MTHFR 677TT who use oral contraceptives have an increased risk of ischemic stroke. When these findings are confirmed, a cost-effectiveness analysis should indicate whether ischemic stroke could be prevented with genetic testing before the start of oral contraceptives.

Deep vein thrombosis

Deep vein thrombosis and its sequelae pulmonary embolism and post-thrombotic syndrome are some of the most common disorders. A thrombus either arises spontaneously or is caused by clinical conditions including surgery, trauma, or prolonged bed rest. In these instances, prophylaxis with low-dose anticoagulation is effective. Diagnosis of deep vein thrombosis relies on imaging techniques such as ultrasonography or venography. Only about 25% of symptomatic patients have a thrombus. Thus, clinical risk assessment and D-dimer measurement are used to rule out deep vein thrombosis. Thrombus progression and embolisation can be prevented by low-molecular-weight heparin followed by vitamin K antagonists. Use of these antagonists for 3-6 months is sufficient for many patients. Those with antithrombin deficiency, the lupus anticoagulant, homozygous or combined defects, or with previous deep vein thrombosis can benefit from indefinite anticoagulation. In cancer patients, low-molecular-weight heparin is more effective than and is at least as safe as vitamin K antagonists. Women seem to have a lower thrombosis risk than men, but pregnancy or use of oral contraceptives or hormone replacement therapy represent important risk factors.