Factor V Leiden: should we screen oral contraceptive users and pregnant women?

Genomic science of risk prediction for venous thromboembolic disease: convenient clarification or compounding complexity

Venous thromboembolism (VTE) refers to abnormal blood clots in veins occurring in 1 to 2 per 1000 individuals every year. While anticoagulant treatment can prevent VTE, it increases the risk of bleeding. This emphasizes the importance of identifying individuals with a high risk of VTE and providing prophylactic interventions to these individuals to reduce both VTE and bleeding risks. Current risk assessment of VTE is based on the combination of mainly clinical risk factors. With the identification of an increasing number of genetic variants associated with the risk of VTE, the addition of genetic findings to clinical prediction models can improve risk prediction for VTE. Especially for individuals in high-risk situations, the added value of genetic findings to clinical prediction models may have benefits such as better prophylaxis of VTE and the reduced side effects of bleeding from unnecessary treatment. Nevertheless, the question of whether these models will eventually have clinical utility remains to be proven. Here, we review the current state of knowledge on genetic risk factors for VTE, explore genetic prediction models for VTE, and discuss their clinical implications and challenges.

Factor V Leiden, estrogen, and multimorbidity association with venous thromboembolism in a British-South Asian cohort

Multimorbidity, estrogen use, and Factor V Leiden (FVL) are known independent risk factors for venous thromboembolism (VTE). This cross-sectional analysis of women in the Genes & Health British-South Asian cohort (N 20,048) linked the F5 SNP rs6025 with estrogen prescribing data and VTE events. Multivariable logistic regression was used to test the association between estrogen use, FVL, common medical co-morbidities, and VTE. Estrogens were prescribed to 30% of women. 3% of participants were FVL carriers. 439 participants had a VTE event (2.2%), and VTE prevalence increased with obesity, hypertension, dyslipidemia, chronic kidney disease, estrogen use, and in the presence of FVL. One medical condition above was independently associated with VTE with an OR 1.6 (CI 1.2-2.0, p 0.001); two medical conditions OR 2.7 (CI 2.0-3.7, p < 0.001); three OR 5.3 (CI 3.8-7.4, p < 0.001); four OR 8.1 (CI 4.9-13.0, p < 0.001). Multimorbidity and FVL compound risk of VTE with estrogen use.

Hormonal Contraception: Systemic Estrogen and Progestin Preparations

Combined hormonal contraception (CHC) are short-acting, reversible methods containing both estrogen and progestin. Available CHC methods include combined oral contraceptives, transdermal patches, and vaginal rings. The combined oral contraceptive remains the most commonly used contraceptive method in the United States. The general principles of CHC will be reviewed, including mechanism of action and effectiveness. Unless otherwise stated, these principles apply to all CHCs. When discussing clinical studies and specific considerations related only to pills, patches, or rings, the method(s) will be specified. Words that specify sex are used when discussing studies in which sex was specified.

Appraising screening, making risk in/visible. The medical debate over Non-Rare Thrombophilia (NRT) testing before prescribing the pill

Non-rare thrombophilia (NRT) are hereditary predispositions to thromboembolism, the most severe side effect of combined hormonal contraception. In the mid-1990s, the identification of NRT stirred up a controversy over the possibility of investigating these genetic variants in women wishing to use contraception. Through a review of literature, this article reconstructs the debate over whether and how this genetic test should be prescribed as a way to reconfigure the risk visibility on pharmacological contraception. The main arguments identified concern the epidemiological, social, economic and clinical aspects of the test. In a context where the overall thrombotic risk for hormonal contraception is largely invisible, the genetic tests turn to embody the thrombotic risk itself. Those who opt for selective screening argue that a better estimation of risk implies a test prescription embed in a global medical assessment of women's individual risk. To advocates of universal or 'extended' screening, the tests are valuable tools to inform women on the thrombotic risk and, as such, appraised as a moral/legal obligation, whatever their predictive power. Risk visibility thus appears as an insightful concept to analyse a complex setting associating clinical, political, social and cultural considerations that touches upon medical power, women's responsibility and drug safety.

Contraception for high risk patients

In the context of medically complicated pregnancies, a "high risk patient" is an individual who is at increased risk for having a complicated pregnancy. These patients often experience limited contraceptive counseling and access, despite the fact that most effective contraceptive methods are associated with less risk than that of pregnancy. Free evidence-based resources are available to assist healthcare providers in discerning fact from myth about the risks of contraception. This review covers all available contraceptive methods, with particular focus on the benefits, risks, and attributes most relevant to high risk patients as well as the benefits and risks of initiating contraception post-pregnancy.

ACOG Practice Bulletin No. 206: Use of Hormonal Contraception in Women With Coexisting Medical Conditions

Although numerous studies have addressed the safety and effectiveness of hormonal contraceptive use in healthy women, data regarding women with underlying medical conditions or other special circumstances are limited. The U.S. Medical Eligibility Criteria (USMEC) for Contraceptive Use, 2016 (), which has been endorsed by the American College of Obstetricians and Gynecologists, is a published guideline based on the best available evidence and expert opinion to help health care providers better care for women with chronic medical problems who need contraception. The goal of this Practice Bulletin is to explain how to use the USMEC rating system in clinical practice and to specifically discuss the rationale behind the ratings for various medical conditions. Contraception for women with human immunodeficiency virus (HIV) (); the use of emergency contraception in women with medical coexisting medical conditions, including obesity, (); and the effect of depot medroxyprogesterone acetate (DMPA) on bone health () are addressed in other documents from the American College of Obstetricians and Gynecologists.

No. 329-Canadian Contraception Consensus Part 4 of 4 Chapter 9: Combined Hormonal Contraception

OBJECTIVE

To provide guidelines for health care providers on the use of contraceptive methods to prevent pregnancy and on the promotion of healthy sexuality.

OUTCOMES

Overall efficacy of cited contraceptive methods, assessing reduction in pregnancy rate, safety, and side effects; the effect of cited contraceptive methods on sexual health and general well-being; and the availability of cited contraceptive methods in Canada.

EVIDENCE

Medline and the Cochrane Database were searched for articles in English on subjects related to contraception, sexuality, and sexual health from January 1994 to December 2015 in order to update the Canadian Contraception Consensus published February-April 2004. Relevant Canadian government publications and position papers from appropriate health and family planning organizations were also reviewed.

VALUES

The quality of the evidence is rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care. Recommendations for practice are ranked according to the method described in this report.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Re-Examining Genetic Screening and Oral Contraceptives: A Patient-Centered Review

The World Health Organization classifies combined hormonal contraception as an unacceptable health risk in the presence of a known thrombogenic mutation but advises against routine thrombophilia screening before initiating combined oral contraceptives (COCs) on the grounds of high screening costs and low prevalence. From the perspective of patient-centered care, we examine cost, prevalence, and other published arguments for and against thrombophilia screening before initiating COCs. Our patient-centered review draws on relevant empirical evidence concerning the advantages and disadvantages of thrombophilia screening, while placing the discussion in the broader context of evolving attitudes toward genetic testing and a shifting policy landscape that provides many women direct access to COCs and/or thrombophilia screening. Given variation in prior probabilities of thrombophilia, expected exposure to other risk factors for venous thromboembolism, attitudes towards risk, expected reactions to a positive test result, ability to pay, and concerns about genetic discrimination, we conclude that the current one-size-fits-most approach is not consistent with patient-centered care. Instead, we advocate for greater patient and provider education concerning the implications of thrombophilia screening. Moreover, we recommend offering patients optional thrombophilia screening before initiating COCs.

Prescription medication changes following direct-to-consumer personal genomic testing: findings from the Impact of Personal Genomics (PGen) Study

Purpose

To measure the frequency of prescription medication changes following direct-to-consumer personal genomic testing (DTC-PGT) and their association with the pharmacogenomic results received.

Methods

New DTC-PGT customers were enrolled in 2012 and completed surveys prior to return of results and 6 months post-results; DTC-PGT results were linked to survey data. ‘Atypical response’ pharmacogenomic results were defined as those indicating an increase or decrease in risk of an adverse drug event or likelihood of therapeutic benefit. At follow-up, participants reported prescription medication changes and health care provider consultation.

Results

Follow-up data were available from 961 participants, of which 54 (5.6%) reported changing a medication they were taking, or starting a new medication, due to their DTC-PGT results. Of these, 45 (83.3%) reported consulting with a health care provider regarding the change. Pharmacogenomic results were available for 961 participants, of which 875 (91.2%) received ≥1 atypical response result. For each such result received, the odds of reporting a prescription medication change increased 1.57 times (95% confidence interval = 1.17, 2.11).

Conclusion

Receipt of pharmacogenomic results indicating atypical drug response is common with DTC-PGT, and associated with prescription medication changes; however, fewer than 1% of consumers report unsupervised changes at 6 months post-testing.

Thrombophilia Screening

Although controversial, screening for thrombophilia has become common. Testing for antiphospholipid antibodies is indicated in order to guide treatment decisions if there is clinical suspicion for antiphospholipid syndrome. The utility of identifying other thrombophilias in symptomatic venous thromboembolism (VTE) is questionable, as the risk of recurrence does not appear to be increased by an appreciable degree with the most common disorders (heterozygosity for factor V Leiden or prothrombin mutation). Although recurrence appears to be increased in those with homozygous or multiple abnormalities and potentially deficiencies in natural anticoagulants, screening to detect these conditions is difficult to justify based on their rarity. The American College of Chest Physicians' current guidelines note the increased risk of recurrence with idiopathic, proximal events regardless of thrombophilia status. They suggest duration of anticoagulation therapy be based on location and provoking factors rather than whether or not the individual has a thrombophilia. Because routine prophylaxis in asymptomatic individuals with thrombophilia is not recommended, screening of asymptomatic family members is difficult to justify. Screening prior to prescribing combination oral contraceptives is not cost effective, may result in unwanted pregnancies, and may have little effect on the overall rate of VTE.

Prevalence of thrombophilia in asymptomatic individuals with a family history of thrombosis

OBJECTIVE

The present study investigates the prevalence of thrombophilia in individuals with first or/and second degree family history of thromboembolism.

MATERIAL-METHODS

The study group consisted of 68 individuals with a first or second degree family history of venous or arterial thromboembolism, but without a personal history of thrombosis. The activity of ATIII, PC, PS, FVIII, FΧΙΙ and total homocysteine was measured on the ACL Advance coagulation analyzer. In addition, hemi-quantitative determination of CRP was performed to exclude an acute phase reaction. The existence of V-Leiden mutation was investigated by the modified pre-dilution method (1:5) with V-DEF. Prothrombin G20210A mutation was detected by the use of an in house PCR protocol. Family history was termed as follows: positive (thrombosis was reported in one parent and his/her family members) (group Α) or strongly positive (thrombosis was reported in both parents and their family members (group Β).

RESULTS

Data analysis revealed decreased activity of ATIII:1.47%, PC:1.47%, and FXII:5.9%, increased activity of FVIII (without inflammation):11.8%, V-Leiden:13%, elevated Hcy:14.7%, and G20210A mutation:2.9%. Group A consisted of 55 individuals (74.5%), whereas group B of 16 (23.5%). The total percentage of thrombophilia was 48.5%, while the percentage within group A was 44.2% and within group B 62.5%.

CONCLUSION

The high prevalence of thrombophilia, reinforce the importance of an extensive laboratory thrombophilia screening when a family history of thromboembolism has been recorded, especially when it concerns both parents and/or their family members and even more when one or more acquired thrombophilic factors coexist.

Testing for inherited thrombophilia and consequences for antithrombotic prophylaxis in patients with venous thromboembolism and their relatives. A review of the Guidelines from Scientific Societies and Working Groups

The clinical penetrance of venous thromboembolism (VTE) susceptibility genes is variable, being lower in heterozygous carriers of factor V Leiden and prothrombin 20210A (mild thrombophilia), and higher in the rare carriers of deficiencies of antithrombin, protein C or S, and those with multiple or homozygous abnormalities (high-risk thrombophilia). The absolute risk of VTE is low, and the utility of laboratory investigation for inherited thrombophilia in patients with VTE and their asymptomatic relatives has been largely debated, leading to the production of several Guidelines from Scientific Societies and Working Groups. The risk for VTE largely depends on the family history of VTE. Therefore, indiscriminate search for carriers is of no utility, and targeted screening is potentially more fruitful. In patients with VTE inherited thrombophilia is not scored as a determinant of recurrence, playing a minor role in the decision of prolonging anticoagulation; indeed, a few guidelines consider testing worthwhile to identify carriers of high-risk thrombophilia, particularly those with a family history of VTE. The identification of the asymptomatic carrier relatives of the probands with VTE and thrombophilia could reduce cases of provoked VTE, offering them primary antithrombotic prophylaxis during risk situations. In most guidelines, this is considered justified only for relatives of probands with a deficiency of natural anticoagulants or multiple abnormalities. Counselling the asymptomatic female relatives of individuals with VTE and/or thrombophilia before pregnancy or the prescription of hormonal treatments should be administered with consideration of the risk driven by the type of thrombophilia and the family history of VTE.

Screening women for oral contraception: can family history identify inherited thrombophilias?

OBJECTIVE

Screening for inherited thrombophilias with laboratory tests is impractical before starting women on combined oral contraceptives. As an alternative, some recommend eliciting a family history of venous thromboembolism. The validity of this approach, however, remains unclear.

DATA SOURCES

We sought all published reports that correlated a family history of venous thromboembolism with any thrombophilia confirmed by laboratory test. We used sequential, overlapping computer searches including MeSH terms used for articles in PubMed, a narrative search phrase in Google Scholar, and then all "related" articles in PubMed for each article included without time or language limitations. This was supplemented by a search of www.clinicaltrials.gov.

METHODS OF STUDY SELECTION

The search yielded 10 reports. Information was sought without success from corresponding authors of four other reports that may have had relevant data. Most reports studied atypical, high-prevalence referral populations.

TABULATION, INTEGRATION, AND RESULTS

Results were presented according to the MOOSE (Meta-analysis of observational studies in epidemiology) guidelines for systematic reviews of observational studies. The patient populations varied widely, definitions of family history included first- or first- and second-degree relatives, and the thrombophilias studied differed among these reports. Hence, aggregation of results was not possible. Despite these differences, all reports consistently documented poor validity of family history for detecting thrombophilias. Sensitivity ranged from 16% to 63% and positive predictive value from 6% to 50% for the various thrombophilias studied. In no study did family history meet the benchmark for a good test (sensitivity plus specificity greater than 150%).

CONCLUSION

Obtaining a family history of venous thromboembolism before starting combined oral contraceptives is not a valid means to detect a woman's risk of thrombophilia. Even in high-prevalence populations, in which the positive predictive value is increased, a positive family history of venous thromboembolism was no better than flipping a coin in predicting thrombophilia.

Flow-simulated thrombin generation profiles as a predictor of thrombotic risk among pre-menopausal women

A large number of individuals are at risk for deep venous thrombosis (DVT) due to alterations in multiple coagulation factors and inhibitors secondary to malignancy, drug interactions, or other general medical conditions. Traditional metrics of haemostasis such as prothrombin time, partial thromboplastin time, and bleeding time, generally estimate anticoagulation status and bleeding risk rather than thrombosis risk. The objective of this study was to correlate a novel, systems-based metric of clotting potential to risk of DVT from a database derived from the Leiden Thrombophilia Study (LETS). We utilised a computational model of blood coagulation, which addresses the interplay between biochemical factors, blood flow, and physiologic surface initiation of coagulation, to calculate an individualised, systems-based metric of clotting potential, termed the flow-simulated thrombin generation (FSTG), for 210 pre-menopausal women in LETS. Both DVT and oral contraceptive (OC) use were associated with higher values of FSTG. We demonstrated a nearly three-fold increased risk of DVT for each standard deviation increase above the mean in FSTG determined under venous flow conditions, which remained highly predictive after adjustment for age and OC status (adjusted odds ratio 2.66; 95% confidence interval 1.69-4.19; p<0.0001). In conclusion, a systems-based screening approach that integrates biochemical factors and flow haemodynamics identifies small subgroups of patients at risk of thrombosis that may benefit from oral anticoagulants.

Impact of smoking during pregnancy on functional coagulation testing

Compounds that are systemically absorbed during the course of cigarette smoking, and their metabolites, affect the coagulation system and cause endothelial dysfunction, dyslipidemia, and platelet activation leading to a prothrombotic state. In addition, smoking increases the activity of fibrinogen, homocysteine, and C-reactive protein. We hypothesize that smoking may affect functional coagulation testing during pregnancy. A secondary analysis of 371 women pregnant with a singleton pregnancy and enrolled in a multicenter, prospective observational study of complications of factor V Leiden mutation subsequently underwent functional coagulation testing for antithrombin III, protein C antigen and activity, and protein S antigen and activity. Smoking was assessed by self-report at time of enrollment (<14 weeks). None of the functional coagulation testing results was altered by maternal smoking during pregnancy. Smoking does not affect the aforementioned functional coagulation testing results during pregnancy.

The Obstetric Medicine Listserv: review of controversies surrounding thrombophilia testing

A woman with no significant personal or family history of thrombosis asked her internist to obtain a thrombophilia work-up prior to starting the combined oral contraceptive for dysmenorrhoea, after another physician advised her to have the test. The case was sent to an international email discussion group where the consensus was that testing should not be done. The responses of the group and review of this controversial topic are presented.

Hormonal contraception--what kind, when, and for whom?

BACKGROUND

In Germany today, one-third of the 20 million women of child-bearing age use combined oral contraceptives (COCs). In this article, we summarize the current knowledge of the mode of action, wanted and unwanted side effects, and long-term risks of COCs. The levonorgestrel intrauterine device (IUD) and long-acting injectable or implantable monophasic progestogen preparations offer comparable contraceptive efficacy to COCs. Nonetheless, they are less frequently used in Germany than COCs, because of their propensity to cause breakthrough bleeding.

METHOD

Selective review of the literature.

RESULTS

COCs suppress gonadotropin secretion and thereby inhibit follicular maturation and ovulation. Their correct use is associated with 0.3 pregnancies per 100 women per year, their typical use, with 1 pregnancy per 100 women per year (Pearl index). COCs have effects on the cardiovascular and hemostatic systems as well as on lipid and carbohydrate metabolism. When given in the presence of specific risk factors, they significantly increase the likelihood of cardiovascular disease and thromboembolism. Women with persistent human papilloma virus (HPV) infection who take COCs are at increased risk of developing invasive cervical cancer. On the other hand, COCs lower the cumulative incidence of endometrial and ovarian cancer by 30% to 50%, and that of colorectal cancer by 20% to 30%. Other malignancies seem to be unaffected by COC use.

CONCLUSION

As long as personal and familial risk factors are carefully considered, COCs constitute a safe, reversible, and well-tolerated method of contraception.

Estrogen and thrombosis: controversies and common sense

Soon after the introduction of hormonal oral contraceptive agents reports of thrombotic complications appeared. In the past several decades, large epidemiological studies helped defined these risks for both arterial and venous complications. Clinicians can assess a patient's risk of thrombosis by both composition of the agent and patients' personal risk factors. For women with bleeding disorders these prothrombotic changes can help decrease bleeding complications. There is now also abundant data on future management of patients with estrogen related thrombosis.

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.

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.

Six-month evaluation of the benefits of the low-dose combined oral contraceptive chlormadinone acetate 2 mg/ethinylestradiol 0.03 mg in young women: results of the prospective, observational, non-interventional, multicentre TeeNIS study

BACKGROUND

In clinical trials and non-interventional studies encompassing > 50,000 women, the monophasic, low-dose combined oral contraceptive (OC) chlormadinone acetate 2 mg/ethinylestradiol 0.03 mg (CMA/EE) has been shown to have various non-contraceptive benefits, as well as contraceptive efficacy and good tolerability. However, there is a paucity of data on use of this OC in young women.

OBJECTIVE

To investigate the relevance of, and changes in, cycle disorders, dysmenorrhoea and skin problems in addition to the efficacy and tolerability of CMA/EE in young women.

METHODS

In this prospective, observational, non-interventional, multicentre study (TeeNIS [Teenager in Non-Interventional Study 2 mg CMA/0.03 mg EE]), young women (< or =20 years of age) were administered CMA/EE (Belara) once daily for 21 days (one blister strip), followed by either a 7-day pill-free interval (conventional cycle regimen; 89.3%) or a pill-free interval after two blister strips or more (extended cycle regimen; 3.7%), over a 6-month treatment period. Data on the mode of administration were missing for 7.1% of patients. The study included a safety population of 7462 patients (the efficacy population consisted of 6885 patients) from 886 gynaecological centres throughout Germany.

RESULTS

Compared with baseline, CMA/EE intake resulted in significant reductions in the numbers of patients with cycle disorders, i.e. spotting (-46%), breakthrough bleeding (-64%), heavy bleeding (-95%) and absence of any bleeding (secondary amenorrhoea; -76%) [all p < or = 0.001], and with dysmenorrhoea (-56%) [p < or = 0.001]. Similarly, there was a significant decrease in the number of patients who used analgesics (-75%), had dysmenorrhoea-associated symptoms (back pain [-69%], headache [-70%], nausea/vomiting [-85%], diarrhoea [-80%], mood swings [-75%] or absence from school/job due to dysmenorrhoea [-92%]), or were restricted in their leisure/sporting activities because of dysmenorrhoea (-83%) [all p < or = 0.001]. Another major benefit of CMA/EE was a significant reduction in the number of patients with skin problems (acne and acne-prone skin) [-55%; p < or = 0.001]. In parallel, the number of patients who needed dermatological treatment (-67%; p < or = 0.001) and concealer cosmetics (-55%; p < or = 0.001) was significantly reduced, and significantly fewer patients felt that their self-esteem was restricted due to skin problems (-67%; p < or = 0.001). There were no relevant weight changes during the observation period; mean bodyweight remained virtually constant (mean weight change <1 kg). At final assessment, physicians' expectations were either 'completely fulfilled' or 'exceeded' with regard to cycle stability, regular bleeding, dysmenorrhoea, effects on weight, and skin problems in 78-95% of patients. CMA/EE provided high contraceptive efficacy with an unadjusted Pearl index of 0.25, calculated from 41 601 cycles of exposure; seven out of eight pregnancies were attributable to user failure, thus resulting in an adjusted Pearl index of 0.03. The tolerability of CMA/EE was excellent, with no unexpected adverse effects.

CONCLUSIONS

This observational, non-interventional study in young women showed that CMA/EE had a significantly beneficial effect on cycle disorders, dysmenorrhoea and skin disorders, and confirmed the good efficacy and tolerability of this combined OC.

Venous thromboembolism: a public health concern

Venous thromboembolism (VTE), defined as deep vein thrombosis, pulmonary embolism, or both, affects an estimated 300,000-600,000 individuals in the U.S. each year, causing considerable morbidity and mortality. It is a disorder that can occur in all races and ethnicities, all age groups, and both genders. With many of the known risk factors-advanced age, immobility, surgery, obesity-increasing in society, VTE is an important and growing public health problem. Recently, a marked increase has occurred in federal and national efforts to raise awareness and acknowledge the need for VTE prevention. Yet, many basic public health functions-surveillance, research, and awareness-are still needed. Learning and understanding more about the burden and causes of VTE, and raising awareness among the public and healthcare providers through a comprehensive public health approach, has enormous potential to prevent and reduce death and morbidity from deep vein thrombosis and pulmonary embolism throughout the U.S.

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.

Should patients with venous thromboembolism be screened for thrombophilia?

In the mid-19th century, Virchow identified hypercoagulability as part of the triad leading to venous thrombosis, but the specific causes of hypercoagulability remained a mystery for another century. The first specific cause to be identified was antithrombin III deficiency. Many other causes of thrombophilia, both genetic and acquired, have been discovered since then. The 2 most common genetic causes of thrombophilia are the Leiden mutation of factor V and the G20210A mutation of prothrombin. The most common acquired cause is antiphospholipid syndrome. These factors increase the relative risk of an initial episode of venous thromboembolism (VTE) by a factor of 2 to 10, but the actual risk remains relatively modest. Therefore, thrombophilia screening to prevent initial episodes of VTE is not indicated, except possibly in women with a family history of idiopathic VTE who are considering oral contraceptive therapy. Some physicians screen for thrombophilia to aid decision making concerning the duration of anticoagulant therapy. However, several studies have demonstrated that, with the exception of antiphospholipid syndrome, thrombophilia does not significantly increase the risk of recurrent VTE. On the other hand, idiopathic VTE significantly increases the risk of recurrence in patients with or without thrombophilia.

Pharmacogenetics: data, concepts and tools to improve drug discovery and drug treatment

Variation in the human genome is a most important cause of variable response to drugs and other xenobiotics. Susceptibility to almost all diseases is determined to some extent by genetic variation. Driven by the advances in molecular biology, pharmacogenetics has evolved within the past 40 years from a niche discipline to a major driving force of clinical pharmacology, and it is currently one of the most actively pursued disciplines in applied biomedical research in general. Nowadays we can assess more than 1,000,000 polymorphisms or the expression of more than 25,000 genes in each participant of a clinical study -- at affordable costs. This has not yet significantly changed common therapeutic practices, but a number of physicians are starting to consider polymorphisms, such as those in CYP2C9, CYP2C19, CYP2D6, TPMT and VKORC1, in daily medical practice. More obviously, pharmacogenetics has changed the practices and requirements in preclinical and clinical drug research; large clinical trials without a pharmacogenomic add-on appear to have become the minority. This review is about how the discipline of pharmacogenetics has evolved from the analysis of single proteins to current approaches involving the broad analyses of the entire genome and of all mRNA species or all metabolites and other approaches aimed at trying to understand the entire biological system. Pharmacogenetics and genomics are becoming substantially integrated fields of the profession of clinical pharmacology, and education in the relevant methods, knowledge and concepts form an indispensable part of the clinical pharmacology curriculum and the professional life of pharmacologists from early drug discovery to pharmacovigilance.

Thrombophilia screening in asymptomatic children

Children with a family history of thrombophilia and/or thrombosis are often referred to pediatric thrombosis centers for evaluation. This article reviews the risks and benefits of thrombophilia testing in this unique population. The article also reviews an approach to testing including a step-wise evaluation and involvement of a genetic counselor.

Hormonal contraceptives as a risk factor for cerebral venous and sinus thrombosis

This review will focus on recent developments in our understanding of cerebral venous and sinus thrombosis (CVST), as a side effect of combined oral contraceptives (COCs) use. Case-control studies have shown an increased risk of CVST in women who use COCs, especially third-generation contraceptives that contain gestodene or desogestrel. Several studies have indicated that the combination of COCs and thrombophilia greatly increased the risk of CVST, particularly in women with hyperhomocysteinaemia, factor V Leiden and the prothrombin-gene mutation. Women with thrombophilia who developed CVST while taking oral contraceptives should be definitively advised to stop using COCs. These patients should be considered for preventive therapy with low doses of heparin in prothrombotic situations such as bed rest or pregnancy, and the duration of anticoagulation should be considered on a case-by-case basis. Patients may be considered candidates for chronic treatment with antiplatelet agents. The best and most cost-effective screening method for thrombophilia in women who are planning to conceive is selective screening based on the presence of previous personal or family history of either prior extracerebral or cerebral venous thromboembolism events.

The Essential Role of Genetic Counseling in Inherited Thrombophilia

The discovery of common genetic polymorphisms that predispose to venous thrombosis has led to the widespread availability of molecular testing for genetic thrombophilia traits. In terms of consent, genetic tests differ significantly from other types of laboratory test. We demonstrate the need for genetic counseling before and after genetic thrombophilia testing, but emphasize that such counseling need not be delivered by a specialist. We describe the potential advantages, limitations, and disadvantages of genetic testing for the common thrombophilic mutations that should be borne in mind when explaining testing to symptomatic individuals and asymptomatic relatives. In the vast majority of cases, genetic testing for thrombophilia is of limited value to the symptomatic patient, and provides minimal benefit over and above the family history when it comes to counseling at-risk family members.

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.

Issues concerning the laboratory investigation of inherited thrombophilia

Inherited thrombophilia, defined as an increased familial tendency to develop thrombosis, may be due to congenital deficiencies or abnormalities of antithrombin, protein C or protein S; to the presence of a point mutation in the factor V gene (G1691A, factor V Leiden) leading to a poor anticoagulant response to activated protein C; or to the presence of a mutation in the prothrombin gene (G20210A) leading to increased plasma levels of prothrombin. The laboratory investigation of inherited thrombophilia should be limited to patients with a history of venous thromboembolism and, if positive, to their family members even though they are still asymptomatic. There is no indication for indiscriminate screening of the general population or screening of asymptomatic women before prescribing oral contraceptives. Testing should be based on the phenotype for antithrombin, protein C and protein S; on the phenotype and genotype (factor V Leiden mutation) for activated protein C resistance; and on the genotype (G20210A mutation) for hyperprothrombinemia. Phenotypic testing should be performed no sooner than three months after acute thrombotic events and at least 2 weeks after discontinuation of oral anticoagulant treatment.

Factor V Leiden as a Common Genetic Risk Factor for Venous Thromboembolism

PURPOSE

To increase nurses' knowledge of the Factor V Leiden (FVL) genetic trait for venous thromboembolism.

ORGANIZING FRAMEWORK

An overview of the history, prevalence, and predisposition of the FVL genetic mutation, including who should be tested and how and in what circumstances people with FVL should be treated.

FINDINGS

FVL is the most commonly recognized genetic trait associated with venous thrombosis. It is found predominantly in Caucasian populations. Biochemically it causes "activated protein C resistance (APCR)." The decision to test for FVL depends on whether the information gained will potentially improve the health care of the person or family. For people who have had deep venous thrombosis, testing for FVL will likely not alter treatment approaches. Currently the advantage for testing is primarily limited to asymptomatic family members who carry FVL and who have had deep vein thrombosis. Close relatives who also carry the mutated gene might benefit from prophylactic anticoagulation when their risk of thrombosis is increased by temporary factors such as surgery.

CONCLUSIONS

Nurses are in a unique position to provide accurate information and counseling when patients and their family members are presented with the results of thrombophilia testing.

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.

The Relationship of the Factor V Leiden Mutation and Pregnancy Outcomes for Mother and Fetus

OBJECTIVE

We sought to estimate the frequency of pregnancy-related thromboembolic events among carriers of the factor V Leiden (FVL) mutation without a personal history of thromboembolism, and to evaluate the impact of maternal and fetal FVL mutation carriage or other thrombophilias on the risk of adverse outcomes.

METHODS

Women with a singleton pregnancy and no history of thromboembolism were recruited at 13 clinical centers before 14 weeks of gestation from April 2000 to August 2001. Each was tested for the FVL mutation, as was the resultant conceptus after delivery or after miscarriage, when available. The incidence of thromboembolism (primary outcome), and of other adverse outcomes, was compared between FVL mutation carriers and noncarriers. We also compared adverse outcomes in a secondary nested carrier-control analysis of FVL mutation and other coagulation abnormalities. In this secondary analysis, we defined carriers as women having one or more of the following traits: carrier for FVL mutation, protein C deficiency, protein S deficiency, antithrombin III deficiency, activated protein C resistance, or lupus anticoagulant-positive, heterozygous for prothrombin G20210A or homozygous for the 5,10 methylenetetrahydrofolate reductase mutations. Carriers of the FVL mutation alone (with or without activated protein C resistance) were compared with those having one or more other coagulation abnormalities and with controls with no coagulation abnormality.

RESULTS

One hundred thirty-four FVL mutation carriers were identified among 4,885 gravidas (2.7%), with both FVL mutation status and pregnancy outcomes available. No thromboembolic events occurred among the FVL mutation carriers (0%, 95% confidence interval 0-2.7%). Three pulmonary emboli and one deep venous thrombosis occurred (0.08%, 95% confidence interval 0.02-0.21%), all occurring in FVL mutation noncarriers. In the nested carrier-control analysis (n = 339), no differences in adverse pregnancy outcomes were observed between FVL mutation carriers, carriers of other coagulation disorders, and controls. Maternal FVL mutation carriage was not associated with increased pregnancy loss, preeclampsia, placental abruption, or small for gestational age births. However, fetal FVL mutation carriage was associated with more frequent preeclampsia among African-American (15.0%) and Hispanic (12.5%) women than white women (2.6%, P = .04), adjusted odds ratio 2.4 (95% confidence interval 1.0-5.2, P = .05).

CONCLUSION

Among women with no history of thromboembolism, maternal heterozygous carriage of the FVL mutation is associated with a low risk of venous thromboembolism in pregnancy. Neither universal screening for the FVL mutation, nor treatment of low-risk carriers during pregnancy is indicated.

LEVEL OF EVIDENCE

II-2.

Trombose venosa profunda como complicação da escleroterapia química no tratamento de telangiectasias dos membros inferiores

Os autores relatam dois casos de escleroterapia de telangiectasias, as quais complicaram com trombose venosa profunda. O primeiro caso foi confirmado por flebografia, e o segundo, por duplex scan. Um paciente, 8 anos após, apresentou uma tromboflebite espontânea de veia safena parva, que resultou em pesquisa de trombofilia positiva para o Fator V Leiden. A outra paciente teve pesquisa de trombofilia negativa. Os relatos de tromboembolismo relacionado à escleroterapia são escassos na literatura. O objetivo do trabalho é alertar para essa possibilidade, valorizando as queixas de dor e edema após a escleroterapia. Havendo suspeita clínica, o duplex scan deve ser realizado.

Genetic screening: carriers and affected individuals

Genetic screening utilizes analytical approaches adapted for high throughput to identify carrier and affected individuals in a targeted population. Currently, genetic screening focuses on carrier screening, prenatal screening, and newborn screening. Newborn screening should serve as a model for all genetic screening, with more than forty years of experience and numerous lessons learned. As with all genetic screening, there are policy concerns in newborn screening regarding which disorders and technologies should be selected, and how centralized or decentralized the process to set policy should be. The need to share experiences and develop databases transcends all other policy considerations in genetic screening. The future will see population-based screening for adult-onset disorders. However, there needs to be extensive research to define predictive risk for various ethnocultural groups and to determine effective interventions. Ethical concerns regarding the timing of population screening, as well as the scope of use of information, will need to be resolved if genomic medicine will achieve its promise of a predictive, preventive, and personalized medicine.