Enhancement by factor V Leiden mutation of risk of deep-vein thrombosis associated with oral contraceptives containing a third-generation progestagen

Oral contraceptives and cardiovascular outcomes: cause or bias?

The 1995-1996 "pill" scare, which suggested that third-generation oral contraceptives (OCs) were associated with a greater risk of venous thromboembolism (VTE) than second-generation OCs, had serious social and public health consequences, as women discontinued OCs, resulting in unwanted pregnancies and unnecessary abortions. This article uses the Bradford Hill criteria, for diagnosing causality from an observed association, to interpret evidence from recent studies as to whether there is any difference in the risk of VTE between third- and second-generation OCs. Bias and the influence of confounders have also been examined in relation to the difference in the risk of VTE between third- and second-generation OCs reported in the 1995-1996 studies. It is clear from the results of this analysis that none of the Bradford Hill criteria are fulfilled. Thus, a causal relationship cannot be inferred from the alleged association of third-generation OCs with VTE. Indeed, it would appear that the unavoidable bias in observational research is a more likely explanation for the apparent difference in the risk of VTE between third- and second-generation OCs in the 1995-1996 studies. Recent studies, which employed more appropriate controls for these biases showed no difference in the risk of VTE between third- and second-generation OCs. A Danish study (1994-1996) demonstrated a lower risk of thrombotic morbidity and mortality with third-generation OCs compared with second-generation OCs. In addition, the Transnational study has shown that third-generation OCs have a significantly lower relative risk (0.3 [0.1-0.9]) for acute myocardial infarction (MI) compared with second-generation products. In conclusion, there is no convincing evidence for a difference in the risk of stroke or VTE between third- and second-generation OCs. Moreover, third-generation OCs may be associated with a lower risk of MI than second-generation OCs.

Congenital and acquired thrombotic risk factors in women using oral contraceptives: clinical aspects

We describe the thrombophilic and clinical characteristics of a group of patients who suffered venous thrombosis (VT) (n = 36) and ischemic stroke (n = 8) while taking oral contraceptives (OC). Our purpose is to ascertain whether there are differences between users of second and third generation progestogen and to investigate the influence of concurrent congenital and acquired risk factors (other than OC) on the onset of the thrombosis. The group of patients included 36 women with VT and eight with ischemic stroke. The patients' recognized predisposing factors were recorded. We also considered age, length of time on OC, types of OC, rethrombosis, family history of VT, and the presence of thrombophilic genetic defects. In the group of patients with VT, 54% were treated with second generation OC (n = 23), and 30% (n = 11) were treated with third generation OC. We found no significant statistical differences with respect to age and length of time on OC between the two types of OC. The prevalence of genetic defects in these patients--factor V (FV) Leiden, prothrombin G20210A mutation and protein S deficiency--was 19% (n = 7), 17% (n = 6), and 8% (n = 3) respectively. We observed the shortest time lapse between initiating OC and the first thrombotic event in carriers of FV Leiden and in patients with combined defects, but the differences were not significant. In patients with ischemic stroke, 50% were treated with second generation OC and 50% were treated with third generation OC. Prothrombin G20210A mutation was detected in two patients. In both patients,the stroke occurred earlier than in the rest of the patients, but these differences were not statistically significant. With respect to preventing thrombotic events in these patients, our data suggest that OC therapy should be avoided in patients with a previous history of thrombosis and in patients with an evident thrombotic tendency in the family. In patients in whom the family history of thrombosis is not very evident, it would be recommended to screen for FV Leiden, prothrombin G20210A mutation, and protein S, and to rule out OC if the patient does in fact have one of these risk factors. Moreover, if a patient develops a thrombotic complication while taking OC, an evaluation to search for a thrombophilic defect is warranted, and at the same time, alternative methods of contraception should be considered.

Prevalence of factor V Leiden mutation in various populations

Resistance to activated protein C (APC) is the most common inherited risk factor for venous thrombosis. Most cases of APC resistance are caused by the point mutation nt 1691 G-A in factor V gene, referred to as factor V Leiden mutation. As initially shown in a Dutch population, this mutation has a carrier rate of 2.9%, the most frequent genetic disposition for thrombophilia and deep venous thrombosis. By large-scale epidemiological studies we have determined the prevalence of factor V Leiden mutation in populations from Poland (200), Argentina (215), Venezuela (126), Costa Rica (196), and India (150). The prevalences have been estimated for Poland (Warsaw) 5.0%, Argentina (Buenos Aires) 5.1%, Venezuela (Valencia) 1.6%, Costa Rica (San José) 2.0%, and India (Punjab) 1.3%. Based on worldwide distribution, it can be hypothesized that the factor V Leiden mutation has originated and accumulated in central European Caucasians and spread over the world by migration.

Are factor V Leiden carriers who use oral contraceptives at extreme risk for venous thromboembolism?

BACKGROUND

Major concern was raised by an earlier study regarding oral contraceptive use in women with the factor V Leiden mutation. A more than 30-fold increase in relative risk for venous thromboembolism was reported; for homozygotes, the relative risk was as much as 100-fold or more.

OBJECTIVE

To replicate the reported risk estimates with a new population-based case-control study.

METHODS

Eighty women with a diagnosis of venous thromboembolism were consecutively identified and compared with population-based controls (n = 406). Factor V Leiden mutation was identified by genotype analysis. The evaluation was performed with conditional logistic regression (matched for 5-year age group).

RESULTS

Matched, adjusted odds ratios (OR) for idiopathic venous thromboembolism in women without and with the factor V Leiden mutation who used oral contraceptives were 4.1 (95% confidence interval (CI) 2.1-7.8) and 10.2 (95% CI 1.2-88.4), respectively. The adjusted OR for factor V Leiden carriers was 2.0 (95% CI 1.0-4.4). The OR for women with the factor V Leiden mutation and oral contraceptive use versus no factor V Leiden mutation and no oral contraceptive use was 10.2 (95% CI 3.8-27.6).

CONCLUSION

The results confirm the increased relative risk of idiopathic venous thromboembolism for users of oral contraceptives and factor V Leiden carriers. However, we suspect that the true risk for women who are factor V Leiden carriers may be increased two- to four-fold rather than seven-fold or more, and that the risk for the combination of factor V Leiden and oral contraceptive use may be increased in the order often- to 15-fold rather than over 30-fold.

Treatment of the antiphospholipid antibody syndrome: progress in the last five years?

The gold standard for treatment of the antiphospholipid antibody syndrome (APS) after thrombosis remains high-intensity warfarin, and, in pregnancy, heparin and aspirin. Exciting developments include the potential role of hydroxychloroquine as a prophylactic drug, stem cell transplantation, and B-cell tolerance. Animal models appear to be a fruitful "proving ground" of new therapies. The introduction of revised classification criteria for APS should aid in appropriate characterization of, and selection of, patients for clinical trials.

Cardiovascular events associated with different combined oral contraceptives: a review of current data

Studies of combined oral contraceptive (COC) use and cardiovascular disease have been conducted against a background of low cardiovascular risk in young women, changing COC composition and changing user selection and monitoring. Studies of myocardial infarction have found inconsistent results, possibly because of differences in the prevalence of risk factors (particularly smoking and raised blood pressure) in the populations studied. In the absence of a history of smoking and other conventional risk factors, current users of modern COCs probably do not have an increased risk of myocardial infarction. Neither are former users at risk. Evidence for important differences in the risk of myocardial infarction between formulations is weak and contradictory. Current users of low estrogen dose COCs have a small increased risk of ischaemic stroke although most of the risk occurs in women with other risk factors (notably smoking, hypertension and probably a history of migraine). Former users of COCs do not have an increased risk of ischaemic stroke. There is insufficient information to determine whether major differences in the risk of ischaemic stroke exist between products. Current users appear to have a modestly elevated risk of haemorrhagic stroke, mainly in women older than 35 years; former users do not. Data examining the risk of haemorrhagic stroke in current COC users with other risk factors are very sparse, as are those relating to the haemorrhagic stroke risk associated with particular COCs. Numerous studies have found, with remarkable consistency, an elevated risk of venous thromboembolism among current users of low estrogen dose COCs. The risk is substantially elevated among women with various inherited clotting factor defects. The effects in COC users with other risk factors for venous thrombosis tend to be less pronounced and more inconsistent. A number of studies have found higher relative risks among current users of low estrogen dose COCs containing desogestrel or gestodene, than among users of similar products containing levonorgestrel. A number of explanations, in terms of bias or confounding, have been proposed for these clinically small differences. At best, empirical evidence for these explanations, is weak. The risk of cardiovascular disease of any description is low in COC users. Women can minimise, and possibly eliminate entirely, their arterial risks by not smoking and by having their blood pressure checked before using a COC (in order to avoid its use if raised blood pressure is discovered). Users may decrease their venous thromboembolic risk by their choice of COC preparation although the effects will be modest.

Pharmacodynamics of oestrogens and progestogens

The ovaries cyclically secrete estradiol and progesterone. Cyclic ovarian estradiol secretion is associated with a bone-saving and vascular protection effect. Endogenous progesterone does not modify the vasodilator effect of oestrogens. At physiological concentrations, the natural sex steroids have low antigonadotropic effects. More potent synthetic derivatives with more antigonadotropic effects were synthesized in the 1950s. After the menopause, there is no longer any need to use hormonal steroids as antigonadotropics. In addition, vascular contraindications are more common in an older population. Contraceptive steroids (particularly ethinyl estradiol) are therefore rarely used. The oestrogen that is most widely prescribed for post-menopausal replacement is a complex formulation of conjugated oestrogens of equine origin that is administered orally in a single daily dose. Improvements in hormone replacement therapy may result from the use of parenteral estradiol (providing sufficient doses are reached) and of a progestogen chemically more similar to progesterone.

Third- and second-generation oral contraceptives are associated with similar risk estimates for venous thromboembolism

A scientific discussion between 1995 and 1999 addressed the question whether second- and third-generation oral contraceptives (OCs) were associated with different risks of venous thromboembolism (VTE). Results from three epidemiological studies became available in the course of 1995, in which such differences were observed. Although it was unclear at that time whether these observations reflected causality or were induced by bias and/or confounding, some regulatory bodies in Europe restricted the indication for use of third-generation oral contraceptives. Immediate media attention generated a pill scare in those, but also other, countries. Indications for the influence of bias were observed in the initial studies of 1995 and further substantiated in subsequent utilization and prescribing surveys. The most important bias seemed to be related to differences in age and duration of use between third- and second-generation OC users. A number of new studies as well as new analyses in two of the 1995 databases included measures to limit the effect of the identified biases/confounders. These studies observed similar risks of venous thromboembolism with second- and third-generation oral contraceptives. Two other recently published studies did not or could not include the same level of control for confounding and reported similar results as the 1995 studies, thus reconfirming the relevance of the identified confounders. Population data show that the massive switch in the UK from third-generation OCs to second-generation OCs in 1995 has not resulted in a reduction of the incidence of VTE in OC users after 1995, illustrating that the risk of VTE is not determined by the type of low-dose pill used. In addition, data from trend analyses, spontaneous reporting and studies addressing hemostatic mechanisms in pill-users also do not support a potential difference in risk of VTE between users of second- and third-generation OCs.

Inherited coagulopathies in OB/GYN

There is an increased risk of venous thrombosis in women with inherited plasma protein coagulopathies (thrombophilias). Although a general screening for thrombophilia is impractical, risk assessment based on identification of other hypercoagulable states-such as a personal or family history of venous thrombosis-can identify patients who may benefit from testing. Those patients testing positive for thrombophilia need to be counseled regarding the implications of oral contraceptive use, hormone replacement therapy, use of selective estrogen receptor modulators, and pregnancy.

Low-dose oral contraceptives and acquired resistance to activated protein C: a randomised cross-over study

BACKGROUND

We have reported previously that, compared with use of second-generation oral contraceptives, the use of third-generation oral contraceptives is associated with increased resistance to the anticoagulant action of activated protein C (APC). Owing to the cross-sectional design of that study, these observations may have been subject to unknown bias or uncontrolled effects of the menstrual cycle. We aimed to overcome these sources of bias by doing a cycle-controlled randomised cross-over trial.

METHODS

The response to APC in plasma was assessed in 33 women who received two consecutive cycles of a second-generation oral contraceptive (150 microg levonorgestrel and 30 microg ethinyloestradiol) or a third-generation oral contraceptive (150 microg desogestrel and 30 microg ethinyloestradiol), and who switched preparations after two pill-free cycles. Normalised APC sensitivity ratios were calculated by measurement of the effect of APC on thrombin generation in the plasma of these women and in pooled plasma from 90 controls.

FINDINGS

Of the 33 women, five were excluded because not all required plasma samples were available. In the remaining 28 women, the normalised APC sensitivity ratio increased during treatment with both preparations. Compared with levonorgestrel, desogestrel-containing oral-contraceptive treatment caused a highly significant (p<0.0001) additional increase in normalised APC sensitivity ratio (0.51 [95% CI 0.37-0.66]). Normalised APC sensitivity ratios during oral-contraceptive treatment correlated with the values before oral-contraceptive use.

INTERPRETATION

Oral-contraceptive treatment diminishes the efficacy with which APC down-regulates in-vitro thrombin formation. This phenomenon, designated as acquired APC resistance, is more pronounced in women using desogestrel-containing oral contraceptives than in women using levonorgestrel-containing preparations. Whether acquired APC resistance induced by oral contraceptives explains the increased risk of venous thromboembolism in oral-contraceptive users remains to be established.

Heritable coagulopathies in pregnancy

Heritable coagulopathies are leading causes of maternal thromboembolism and are associated with an increased risk of maternal and perinatal morbidity and mortality. The most common of these disorders are antithrombin III deficiency, protein C deficiency, protein S deficiency, activated protein C resistance resulting from the factor V Leiden mutation, elevated prothrombin activity associated with a mutation in the prothrombin gene, and hyperhomocystinemia. The maternal risk of a thromboembolic episode is increased by a factor of eight in the presence of any of these heritable states. In addition, the relative risk for a stillbirth in the presence of one of these disorders is 3.6. These conditions are also associated with intrauterine growth retardation and preeclampsia. Proper management of heritable coagulopathies during pregnancy is essential to reduce the risk of these serious sequelae. Patients with newly diagnosed deep-vein thromboses or pulmonary emboli should be treated with therapeutic levels of unfractionated or low molecular weight heparin, followed by subsequent prophylactic heparin therapy. All patients with a history of thromboembolism before pregnancy or evidence of any of these coagulopathies may be offered prophylactic therapy with low molecular weight heparin. Patients with antithrombin III deficiency should receive full therapeutic heparin therapy for the entire pregnancy, irrespective of their thromboembolic history. Postpartum therapy with either heparin or warfarin is required in all cases.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader will be able to describe the various heritable coagulopathies that can complicate pregnancy, to state the potential adverse effects of heritable coagulopathies in pregnancy, and to explain the management of heritable coagulopathies during pregnancy.

Risk of idiopathic venous thromboembolism in users of progestagens alone

Overall, there was a modest, non-significant, positive association between exposure to progestagens alone and venous thromboembolism (VTE). There was no effect with progestagens alone used for contraception, whereas there was a substantial association with the higher dose progestagens used for other reasons.

Benefits and risks of third-generation oral contraceptives

OBJECTIVE

To evaluate the risks and benefits of third-generation oral contraceptives.

DATA SOURCES

A MEDLINE search was done for English language articles published from 1985 through 1998 relating to the side-effect profile of third-generation oral contraceptives or their association with cardiovascular or thromboembolic disease. All articles containing original data were included.

DATA SYNTHESIS

The risk of venous thromboembolism appears to be 1.5- to 2.7-fold greater in users of third-generation, compared with second-generation, oral contraceptives. Compared with nonusers, women who use third-generation oral contraceptives may have a 4.8- to 9.4-fold greater risk of venous thromboembolism. Users of third-generation oral contraceptives do not appear to have an increased risk of myocardial infarction compared with nonusers and may have risk of myocardial infarction of 0.26 to 0.7 compared with second-generation users. Whether third-generation oral contraceptives are associated with a decreased stroke risk is still not clear.

CONCLUSIONS

Although third-generation oral contraceptives most likely increase a user's risk of venous thromboembolism, their improved side-effect profile and their possible decreased association with myocardial infarction and stroke may make them a useful new class of oral contraceptives for most women except those at increased risk of venous thrombosis.

Preeclampsia and genetic risk factors for thrombosis: a case-control study

OBJECTIVE

Recently, it has been proposed that hereditary coagulation abnormalities leading to an increased venous thrombosis risk may play a role in the development of preeclampsia. We tested this hypothesis in women who have had preeclampsia compared with matched control subjects.

STUDY DESIGN

We conducted a case-control study of 163 women with preeclampsia during 1991-1996. Control subjects were matched for age and delivery date. Patients and control subjects were tested for the presence of factor V Leiden, prothrombin 20210A allele, protein C, protein S, and antithrombin deficiency. Logistic regression methods were used for data analysis.

RESULTS

The prevalence of these genetic risk factors was similar in the patient group (12.9%) and the control group (12.9%; odds ratio, 1.0; 95% confidence interval, 0.5-3.9). Unexpectedly, we found a high prevalence of factor V Leiden in the control group (9.2%).

CONCLUSION

We found no differences in the prevalence of genetic risk factors of thrombosis in women with preeclampsia compared with control subjects.

The role of inherited thrombophilia in venous thromboembolism associated with pregnancy

Venous thromboembolism is an important cause of maternal morbidity and mortality. The puerperium should be regarded as the period of greatest risk. However, fatalities in early pregnancy emphasise the need to assess thrombotic risk at all stages of pregnancy. In many cases those at increased risk are potentially identifiable on clinical grounds alone such as those with a personal or family history of venous thromboembolism, obesity, or surgery. Identification of women with multiple clinical risks for thrombosis during pregnancy remains the key to reducing the incidence of this condition. In women who present with a personal or family history of proven venous thromboembolism, thrombophilia screening should be performed in early pregnancy, since the results may influence subsequent management during pregnancy. The investigation and management of patients considered at increased risk of venous thrombosis during pregnancy requires close liaison between obstetricians and haematologists familiar with this rapidly expanding and complex field of thrombophilia.

Oral contraceptives highlight the genotype-specific association between serum phospholipids and activated factor VII

The present analysis was undertaken to study the effect of oral contraceptive (OC) use on activated factor VII (FVIIa) in subjects characterized by FVII genotypes, with the further aim of evaluating the role of lipids in this pharmacological interaction. In OC users (n=42) and nonusers (n=130) of comparable age, we examined the FVII phenotypic variables (FVII coagulant activity [FVIIc], FVII antigen, and FVIIa), FVII genotypes (the 353R/Q and 5'F7 polymorphisms analyzed in combination; alleles M1/M2 and A1/A2, respectively), and a number of lipid and lipoprotein parameters: serum concentrations of total cholesterol (chol), low density lipoprotein and high density lipoprotein-chol, triglycerides, phospholipids (PhLs), apolipoprotein A1, and lipoprotein(a). PhLs, triglycerides, apolipoprotein A1, chol, FVII antigen, FVIIc, and high density lipoprotein-chol levels were shown to be statistically higher in users than nonusers. FVII levels, particularly those of FVIIa and FVIIc, were much higher in homozygotes for the A1 and M1 alleles (A11 M11), especially in OC users. A strong association was found between PhL and FVIIa: in the multiple regression analysis, women taking OCs who had elevated PhL concentrations also had very high levels of FVIIa, but only if their genotype was A11 M11. These results indicate that the increased FVII levels in OC users depend on the FVII genotype and that high PhL concentrations predict very high levels of FVIIa and FVIIc.

Prescribing and managing oral contraceptive pills and emergency contraception for adolescents

Combination OCPs are safe and effective ways to prevent unintended adolescent pregnancy if they are used properly. Numerous noncontraceptive benefits of OCPs can bolster continued combination OCP use. Progestin-only OCPs are an option, particularly for young women with medical contraindications to taking estrogens; however, because of their lower efficacy, progestin-only pills are not the first choice for oral contraception for adolescents. Health care providers can give young women a second chance to prevent unintended pregnancy by improving their access to emergency contraception through educating and counseling about emergency contraception at all office visits, by prescribing emergency contraceptive pills in advance, or by prescribing emergency contraceptive pills over the telephone.

Benefits and risks of oral contraceptives

The major benefits of modern low-dose oral contraceptives include relative safety and a high degree of efficacy, decreasing the need for abortion or surgical sterilization; reduced risks of bacterial (but not viral) pelvic inflammatory disease and of endometrial and ovarian cancer; improved menstrual regularity, with less dysmenorrhea and blood flow; and, when low-dose combination (not progestogen-only) oral contraceptives are used, reduced acne and hirsutism. Major risks are cardiovascular. Preliminary data from nonrandomized studies suggest that oral contraceptives containing third-generation progestogens are associated with increased risk of venous thromboembolism, particularly in carriers of the coagulation factor V Leiden mutation. The risk of arterial thrombosis, such as myocardial infarction or stroke, may be directly related to estrogen dose, particularly in women who have hypertension, smoke, or are >35 years old. Considering that only users aged >/=30 years who smoke >/=25 cigarettes/d have a higher estimated mortality rate than that of pregnant women, the benefits of oral contraceptives appear to outweigh their risks.

Cardiovascular disease: pathogenesis, epidemiology, and risk among users of oral contraceptives who smoke

Smoking increases the risk of lung cancer and cardiovascular disease among persons of both sexes. The risk of cardiovascular disease is further increased among users of oral contraceptives who smoke, particularly those who are >/=35 years old or carry the coagulation factor V Leiden mutation. Other important cardiovascular disease risk factors in women include waist/hip girth ratio >0.8, high concentration of low-density lipoprotein cholesterol (>115 mg/dL), high triglyceride level (>/=150 mg/dL) with low concentration of high-density lipoprotein cholesterol (</=45 mg/dL), high ratio of total cholesterol/high-density lipoprotein (4.0), high ratio of low-density lipoprotein/high-density lipoprotein (3.0), glucose values >/=100 mg/dL, hypertension, lack of physical activity, and high-fat diet. Most excess cardiovascular disease among users of oral contraceptives is due to thrombosis (not atherosclerosis); studies indicate that the lower the oral contraceptive estrogen dose is, the lower is this risk. Oral contraceptives containing the third-generation progestins desogestrel and gestodene have been associated with greater risks of venous thromboembolism than are associated with older progestins, although there is some controversy surrounding these findings.

The differential risk of oral contraceptives: the impact of full exposure history

Previous discussions have indicated that the small increases of risk of venous thromboembolism (VTE) associated with newer combined oral contraceptives (third generation, containing desogestrel and gestodene) may be attributed to bias due to cohort effects. In a case-control analysis, this may produce an overestimate of risk of newer preparations. In 10 centres in Germany and the UK, the Transnational Study analysed data from 502 women aged 16-44 years with VTE, and from 1864 controls matched for 5-year age group and region. Information on lifetime exposure history from all subjects was added to the dataset used in previous analyses and entered into a Cox regression model with time-dependent covariates. Based on 17 622 continuous exposure episodes comprising 47 914 person-years of observation, the adjusted hazard ratio (equivalent to odds ratio, OR) of VTE for the comparison of current users of third-generation versus current users of second-generation (primarily levonorgestrel compounds) combined oral contraceptives was 0.8 (0.5 to 1.3). The OR obtained in standard case-control analysis had been 1.5 (1.1 to 2.1). Adjustment for past exposures includes more information and appears more valid than the standard cross-sectional analysis. Using this approach, the Transnational Study data show no evidence for an increased risk of VTE with third- compared with second-generation combined oral contraceptives.

Is there an increased risk of stroke associated with oral contraceptives?

In the last few years several studies were published about the relationship between oral contraceptive use, estrogen dose, different types of progestogens, cigarette smoking and the risk of stroke. There is a persistent association between the use of oral contraceptives containing more than 50microg of ethinylestradiol and the risk of stroke. Also, cigarette smoking seems to be a strong additive risk factor, especially in women >35 years old even with lower doses (< or =30microg) of estrogen. Unlike oral contraceptives containing >50microg of estrogen, currently there is no convincing evidence that the use of oral contraceptives containing <50microg in the absence of smoking is associated with any meaningful increase in the risk of ischaemic or haemorrhagic stroke. Progestogen-only pills are not associated with an increased risk of stroke. A specific type of progestogen in combined pills was associated with an increased risk of stroke in a few studies. Data regarding this issue is, however, inconsistent and controversial and needs further investigation. There were few if any studies that have addressed the effects of new types of progestogens (i.e. norgestimate, norgestrel or gestodene) and formulations containing 20microg of ethinylestradiol. At the present time we find no reason to alter the current practice in prescribing oral contraceptives. We do concede, however, that there might be a slight causal relationship between use of oral contraceptives containing <50microg of ethinylestradiol and stroke that did not reach statistical significance. This relationship is rare and should be viewed in context with the many benefits of oral contraceptives. Underlying risk factors for stroke such as factor V Leiden mutation and other thrombophilias might explain the role of oral contraceptive-induced stroke.

An open label, randomized study to evaluate the effects of seven monophasic oral contraceptive regimens on hemostatic variables. Outline of the protocol. Oral Contraceptive and Hemostasis Study Group

Complementary to the epidemiological knowledge on the association between oral contraceptive use and the occurrence of venous thromboembolism, a study was designed to obtain more conclusive data regarding the effect of estrogen dose and progestogen type of oral contraceptives on risk markers for the occurrence of venous thromboembolism. The protocol for this multicenter, randomized, open label, parallel group, comparative study is outlined in the present article. A total of 730 healthy, nonsmoking, mulliparous women were treated for six cycles with one of the seven monophasic oral contraceptives tested in this study. The effects of progestogen type (desogestrel, gestodene, levonorgestrel, and norgestimate) and the effects of ethinyl estradiol dose (50, 30, and 20 micrograms) on various hemostatic variables was assessed, including the key components of the anticoagulant and fibrinolytic system, as well as the coagulation system. The primary outcome variables in the study were prothrombin fragment 1 + 2 and D-dimer.

Oral contraceptives and vascular reactivity of great vessels in women

Blood pressure and great vessel vascular reactivity, evaluated by color Doppler ultrasound, were investigated in users of third-generation oral contraceptives (n = 18) compared to non-users, who were studied either in the follicular (n = 8) or in the luteal (n = 10) phase of the menstrual cycle. Blood pressure measured at rest in the supine position, evaluated both in the follicular phase and in the luteal phase, was similar between oral contraceptive users and non-users. The pulsatility index (an indirect index of resistance to blood flow) of both the internal carotid artery and the axillary artery was similar in control women studied in the follicular phase and in the luteal phase. By contrast, in users of oral contraceptives, pulsatility index values of the internal carotid artery tended to be higher, whilst those of the axillary artery were significantly higher, than those of women in either the follicular phase (p < 0.01) or the luteal phase (p < 0.025). In conclusion, new third-generation oral contraceptives do not have a significant impact on blood pressure control, but still tend to increase vascular resistance to blood flow, particularly in areas more involved in the regulation of blood pressure, for example the axillary artery.

Effects of oral contraceptives on hemostasis and thrombosis

OBJECTIVE

The object of the study was to determine the effects of oral contraceptives on blood coagulation, in particular on the protein C pathway.

STUDY DESIGN

Plasma samples from healthy men, from healthy female users and nonusers of oral contraceptives, and from heterozygous and homozygous male and female carriers of the factor V Leiden mutation (some of whom used oral contraceptives) were tested for their sensitivity to activated protein C by means of a new activated protein C resistance test developed in our laboratory. This assay is based on measurement of the effect of activated protein C on the endogenous thrombin potential, the time integral of thrombin generation initiated in plasma through the extrinsic coagulation pathway.

RESULTS

The normalized activated protein C sensitivity ratio ([ETP+APC/ETP-APC]plasma/[ETP+APC/ETP-APC]normal plasma, where ETP is endogenous thrombin potential, +APC is with activated protein C, and -APC is without activated protein C) of men was lower than that of healthy female nonusers of oral contraceptives. The normalized activated protein C sensitivity ratio of the users of oral contraceptives was significantly higher than that of nonusers of oral contraceptives. The normalized activated protein C sensitivity ratio of women who were using oral contraceptives with third-generation progestogens was higher than that of users of oral contraceptives with second-generation progestogens. Furthermore, the normalized activated protein C sensitivity ratio of 80% of the users of third-generation preparations fell within the 5th to 95th percentile of the normalized activated protein C sensitivity ratio of female carriers of factor V Leiden, a mutation that is associated with hereditary resistance to activated protein C and with an increased risk of venous thromboembolism.

CONCLUSION

Acquired activated protein C resistance may explain the increased risk of venous thromboembolism among users of oral contraceptives reported in epidemiologic studies and the higher risk of venous thromboembolism among users of oral contraceptives with third- versus second-generation progestogens.

Screening for activated protein C resistance before oral contraceptive treatment: a pilot study

The feasibility and cost-effectiveness of screening women for congenital thrombophilic alterations before oral contraceptive (OC) treatment was investigated. A total of 525 women (mean age 21.9 years, 73% aged < 25 years) were examined before their first OC course. At first screening, completely normal results were recorded in 485 (92.4%) women, the remaining showing single (n = 34) or multiple (n = 6) alterations. At second examination (possible in 37 of 40), activated protein C resistance (APCR) was confirmed in 21 cases (4.0%, 18 with factor V Leiden), protein C, or protein S reduction in 8 (1.5%) and 2 (0.4%) cases, respectively. No cases with antithrombin III deficiency were detected. The global estimated cost ($US) to detect one altered case was: $7795 for protein S, $2696 for antithrombin III (no case found), $1374 for protein C and $433 for APCR. The present study confirms that extensive thrombophilic screening before OC treatment is not currently advisable. APCR assessment, however, seems to have a favorable cost-effectiveness ratio: the alteration is frequent and has a synergistic effect with OC; sensibility and specificity of some methods are good; family history is unreliable to single out possible carriers; finally, carriers can be fully informed of their increased thrombotic risk if treated with OC and can receive thromboprophylaxis during life situations associated with high thrombotic risk (e.g., pregnancy and puerperium).

Factor V Leiden: should all women be screened prior to commencing the contraceptive pill?

It has been evident for over 30 years that combined oral contraceptive pills (OCP) increase the risk of venous thromboembolism. Recently, it has been suggested that there is an interaction between combined OCPs and the factor V Leiden mutation with the result that the relative risk of venous thromboembolism (VTE) is higher than expected in women who have this heritable thrombophilic defect using combined oral contraceptive pills. In Caucasian populations, factor V Leiden is very prevalent, being present in between 3 and 7% of Europeans and white North Americans. The high prevalence of the defect and its apparent interaction with combined oral contraceptive pills has led to the suggestion that all women should be screened for factor V Leiden prior to commencing contraceptive pills. Although the relative risk of VTE is very significantly increased in factor V Leiden positive women using contraceptive pills, the absolute incidence of venous thrombotic events is low and fatal pulmonary embolism is rare. It would be extremely costly to screen all women for the factor V Leiden mutation and unlikely to be deemed cost-effective. Widespread screening would result in 3-7% of women being denied the most effective and acceptable form of contraception and may influence negotiations with life insurers. It is suggested that only selected women, i.e. those with a personal history of previous venous thromboembolism and those with a clear family history of VTE are offered screening for thrombophilic defects.

Update on androgenicity

The development of a new generation of progestins deemed less androgenic than their earlier counterparts has led to a number of misconceptions regarding their possible benefits in combination oral contraceptives. All combination oral contraceptives are beneficial for treating such androgenic conditions as acne and hirsutism. The only expressed androgenic effect of some first- and second-generation combined oral contraceptives are changes in plasma lipid and lipoprotein levels. However, the overall effect of today's low-dose oral contraceptives is largely lipid neutral, and human and monkey studies have shown that oral contraceptive use is associated with reduced, not increased, atherosclerosis rates. Myocardial infarction rates are not increased among oral contraceptive users, except among those who are heavy smokers.

Risk of venous thromboembolism with third-generation oral contraceptives: A review

Recent data indicate that users of third-generation oral contraceptives, those containing the new progestins desogestrel, gestodene, and norgestimate, have 2 to 3 times the risk of venous thromboembolism faced by users of second-generation oral contraceptives. The risk of development of deep vein thrombosis was also found to be 2 to 5 times greater with a low-estrogen, desogestrel-containing oral contraceptive than with second-generation monophasic and triphasic preparations. Investigators point to an acquired resistance to the anticoagulation effects of activated protein C, the most common cause of hereditary thrombophilia, as a possible mechanism. The American College of Obstetrics and Gynecology's Committee on Gynecologic Practice reconfirms the increased risk of venous thromboembolism associated with third-generation progestins versus other progestins. Because the third-generation oral contraceptives may have benefit for some patients, however, it defers to the individual clinician's and patient's judgment regarding the use of a desogestrel-containing formulation (the only third-generation progestin available in the United States).

Estimates of the risk of cardiovascular death attributable to low-dose oral contraceptives in the United States

OBJECTIVE

Our purpose was to estimate the annual risk of death in the United States from cardiovascular disease attributable to low-dose combination oral contraceptives.

STUDY DESIGN

Estimates of the risk of death from cardiovascular disease attributable to low-dose oral contraceptives were modeled on data from studies published through 1997 and from age-specific mortality rates in the United States for 1993 and 1994.

RESULTS

Attributable risk of death from cardiovascular disease resulting from oral contraceptive use is 0.06 and 3.0 per 100,000 nonsmokers 15 to 34 years of age and 35 to 44 years of age, respectively. In smokers this risk increases, respectively, to 1.73 and 19.4 per 100,000 users in these 2 age groups; however, 97% and 85% of this risk is due to the combined effects of smoking and using oral contraceptives. The attributable risk of death from cardiovascular disease in nonsmoking oral contraceptive users is lower than the risk of death from pregnancy in nonusers of oral contraceptives at all ages; however, among smoking oral contraceptive users more than 35 years of age, the excess risk of death from oral contraceptives is higher than the risk of death from pregnancy.

CONCLUSION

There is virtually no excess attributable risk of death from cardiovascular disease related to oral contraceptive use in young women. However, smokers more than 35 years of age should use a nonestrogen contraceptive.

Laboratory evaluation of hypercoagulable states

The number of well-characterized hereditary and acquired hypercoagulable conditions is increasing, such that in many thrombophilic patients, the laboratory can now identify a hypercoagulable condition. This review describes the currently known hypercoagulable states that predispose patients to venous, and in some instances, arterial thrombosis. For each condition, the discussion includes the incidence, magnitude of the thrombotic risk in the general population in comparison with symptomatic families, synergistic interactions among the various hypercoagulable conditions, molecular pathogenesis, and interpretation of laboratory test results. In addition, recommendations for laboratory testing are summarized.

Factor V Leiden mutation: a nursing perspective

The factor V Leiden mutation is a recently described autosomal dominant genetic risk factor for venous thromboembolism (VTE). Persons who are heterozygous or homozygous for this disorder are at 4 to 7 times and 50 to 100 times increased risk, respectively, for VTE. In particular, women have unique challenges because the presence of the Leiden mutation in combination with pregnancy or use of oral contraceptives results in an even greater increased risk for VTE. This article will review the factor V Leiden mutation, its association with VTE, and the genetic inheritance pattern and ethnic distribution. Oral contraceptive use, pregnancy, and hormone replacement therapy in women with the Leiden mutation will be discussed. Screening issues and management for all patients, and women in particular, will be addressed. Nursing implications for care management of this group of patients is complex and requires evaluation of the significance of newly defined genetic disorders such as the factor V Leiden mutation. Nurses need to be knowledgeable about genetic screening, risk factors, risk-reduction counseling, and considerations for long-term therapy, which include quality of life issues. Two case studies exemplify many of the issues that will be discussed.

Resistance to activated protein C and the leiden mutation: high prevalence in patients with abruptio placentae

OBJECTIVE

The Leiden mutation, a point mutation in the gene encoding coagulation factor V, is associated with a high frequency of thromboembolic phenomena. It has recently been connected with adverse outcomes of pregnancy. We carried out this study to define its connection with abruptio placentae.

STUDY DESIGN

Twenty-seven women who had abruptio placentae and 29 control subjects matched for age, parity, and ethnic origin were studied. We studied all women for possible hypercoagulation defects. All women demonstrating resistance to activated protein C were studied for the presence of the factor V Leiden mutation.

RESULTS

Seventeen of 27 case patients had an activated protein C ratio </=2.5, compared with 5 of 29 control subjects (odds ratio 8.16, 95% confidence interval 3.6-12.75, P =.00125). Participants with activated protein C ratios </=2.5 underwent deoxyribonucleic acid analysis. Eight case patients were found to have the factor V Leiden mutation (5 heterozygous and 3 homozygous, 29.6%), compared with 1 heterozygote among the control subjects who were tested (3.4%).

CONCLUSION

Factor V Leiden mutation was found quite frequently in patients with abruptio placentae.

Combined oral contraceptives, smoking, and cardiovascular risk

STUDY OBJECTIVE

To assess age specific incidence and mortality of stroke, acute myocardial infarction (AMI), and idiopathic venous thromboembolism (VTE) associated with use of modern low dose combined oral contraceptives (OCs) and the interaction with smoking.

DESIGN

Hospital-based case-control study.

SETTING

Hospitals in Oxford region in the United Kingdom, which covered a defined population, during the period 1989-1993.

METHODS

Relative risk estimates from the WHO Collaborative Study and observed incidence rates from the Oxford region were used to estimate age specific incidence of each disease among women without cardiovascular risk factors and model total cardiovascular incidence and mortality.

RESULTS

Among women who did not use OCs, smoke nor had any other cardiovascular risk factors, total incidence of stroke and AMI were less than 2 events per 100,000 woman years in those aged 20-24 years and rose exponentially with age to 8 events per 100,000 among women aged 40-44 years. Incidence of idiopathic VTE among women who did not use OCs rose linearly with age (from 3.3 per 100,000 at ages 20-24 years to 5.8 per 100,000 at ages 40-44 years). The increased risk of idiopathic VTE associated with OC use among non-smokers constituted over 90% of all cardiovascular events for women aged 20-24 years and more than 60% in those aged 40-44 years. Fatal cardiovascular events were dominated by haemorrhagic stroke and AMI, and among OC users who smoked these two diseases accounted for 80% of cardiovascular deaths among women aged 20-24 years, rising to 97% among those aged 40-44 years. Cardiovascular mortality associated with smoking was greater than that associated with OC use at all ages. Attributable risk associated with OC use was 1 death per 370,000 users annually among women aged 20-24 years, 1 per 170,000 at ages 30-34 years, and 1 per 37,000 at ages 40-44 years. Among smokers, the cardiovascular mortality attributable to OC use was estimated to be about 1 per 100,000 users annually among women aged less than 35 years, and about 1 per 10,000 users annually among those above the age of 35 years.

CONCLUSION

The incidence of fatal cardiovascular events among women aged less than 35 years is low. The VTE risk associated with OC use is the largest contributor to OC induced adverse effects. The potentially avoidable excess VTE risk associated with the newer progestogens desogestrel and gestodene would account for a substantial proportion of total cardiovascular morbidity in this age group. For women over age 35 years the absolute risks associated with OC use and smoking are greater because of the steeply rising incidence of arterial diseases. The combination of smoking and OC use among such women is associated with particularly increased risks. Any potential reduction in AMI or stroke risk with use of third generation OCs would be a more important consideration among older compared with younger women, particularly if they smoke. However, the mortality associated with smoking is far greater than that associated with OC use (of any type) at all ages.

Effect of desogestrel-containing oral contraceptives on vascular reactivity and catecholamine levels

The modifications induced by new oral contraceptives (OC) on blood pressure, great vessel vascular reactivity by color Doppler, and catecholamine levels were investigated. Young healthy women not taking OC (n = 22; controls) or receiving, for > or = 6 months, OC containing desogestrel with either 30 micrograms (n = 14) or 20 micrograms of EE (n = 8) were enrolled. Blood pressure measured at rest in supine position was similar between controls and OC users. The pulsatility index (PI), an indirect index of resistance to blood flow, of axillary artery was significantly higher (p < 0.05) in 30 micrograms than in 20 micrograms EE OC users or controls. A similar trend, albeit not significant, was observed for the internal carotid artery PI. Norepinephrine (p < 0.01) and dopamine (p < 0.05) but not epinephrine levels, were lower in 30 micrograms EE OC users than in 20 micrograms EE OC users or controls. Thus, both 20 micrograms and 30 micrograms EE OC had no negative effect on blood pressure, but the 30 micrograms EE OC tended to increase great vessel resistance to blood flow, independently of catecholamine levels.

The epidemiology of oral contraceptive use: a critical review of the studies on oral contraceptives and the health of young women

Recent observational studies show a slightly increased risk of venous thromboembolism among users of newer combined oral contraceptives with odds ratios between 0.8 and 2.3 when compared with users of older oral contraceptives. The controversy regarding the newer oral contraceptives is reviewed by analyzing the recent studies with epidemiologic methods. Key studies on venous thromboembolism may be subject to bias related to prescribing criteria, diagnostics, hospital referral, cohort effects, and residual confounding, resulting in an overestimate of the risk of venous thromboembolism associated with the newer oral contraceptives. The studies on stroke showed no difference between newer and older oral contraceptives, and studies on myocardial infarction show that newer oral contraceptives carry no risk of this event. Newer-generation oral contraceptives are unlikely to constitute a significant hazard to the user population with regard to venous thromboembolism. The results for other disease entities also need to be taken into account when the results on venous thromboembolism are assessed on a population basis.

Prevalence of factor V Leiden (APCR) and other inherited thrombophilias in young patients with myocardial infarction and normal coronary arteries

OBJECTIVE

To investigate the role of activated protein C resistance (APCR, factor V Leiden) in coronary artery thrombosis.

METHODS

The prevalence of APCR and of congenital deficiencies of antithrombin III, protein C, protein S, plasminogen, and factor XII was investigated in adult patients under 45 years of age with acute myocardial infarction. The results were compared with those of a group of 53 age and sex matched control subjects.

RESULTS

Among 75 patients under the age of 45 years who were admitted from November 1994 to April 1996 for acute myocardial infarction, 22 (29.3%) had normal coronary arteriography (group I) and 53 (70.7%) had significant coronary artery disease (group II). Inherited thrombophilia was more often found in group I (4/22, 18.2%) than in group II (4/53, 7.5%) but the difference was not significant (F test: p = 0.22). The prevalence of APCR was 9.1% (2/22) in group I, 3.8% (2/53) in group 2 (p = 0.57), and 3.8% (2/53) in the normal control group (p = 0.57).

CONCLUSIONS

The prevalence of congenital thrombophilias, including APCR, does not seem to be increased in young patients with myocardial infarction and normal coronary angiograms, compared with young patients with coronary atherosclerosis and with normal control subjects. However, the statistical power of the study is too low to detect a significant difference and these results are published to allow a meta-analysis of this problem in the future.

Myocardial infarction and stroke in young women: what is the impact of oral contraceptives?

Recent discussions have centered on the small apparent risk increase for venous thromboembolism found with newer oral contraceptives (third-generation oral contraceptives containing the progestins desogestrel and gestodene) compared with older oral contraceptives (second-generation). This article reviews the studies addressing the association between oral contraceptive use and thromboembolic conditions affecting the arterial system, ischemic stroke, and myocardial infarction. Differences are found between a US database study, which showed no risk of ischemic stroke or myocardial infarction associated with low-dose oral contraceptive use, and the European studies, which showed oral contraceptive use in general to be associated with increased risks of ischemic stroke and myocardial infarction. The European studies showed no difference between oral contraceptive generations with respect to the occurrence of ischemic stroke; however, the risk of myocardial infarction associated with oral contraceptive use was consistently lower for third- than for second-generation oral contraceptives. Although there seems to be no differential risk of ischemic stroke associated with oral contraceptive generations, third-generation oral contraceptives appear to be consistently associated with no excess risk of myocardial infarction. In all instances, however, cardiovascular risk factors other than oral contraceptive use play the predominant role in the occurrence of ischemic stroke and myocardial infarction.

Contraceptives: regional perspectives, issues, and unmet needs--the European perspective

Existing methods of contraception clearly do not meet all the needs of European women. Studies have shown that women continue to want contraceptive methods with the lowest possible risks and highest possible health care benefits. In addition to offering health benefits, these methods must have extremely low failure rates and permit good compliance. Studies reflect high rates of non-compliance and discontinuation with the combined OC and the progestogen-only contraceptive pill. Methods, such as the IUDs, subdermal implants, and injectable contraceptives offer significant advances in continuation of contraception coupled with low failure rates. In the past, the use of injectable contraceptive methods in Europe was low because only the progestogen-alone methods were available - Depo-Provera and Noristerat. Both methods have been linked with extensive menstrual cycle disturbance, which has not been noted with the combined injectable methods, as reviewed by Newton et al.. The author believes that combined injectable methods should be added to the list of contraceptive methods freely available to women in Europe, not only because of their lack of disruption of the menstrual cycle, but also because of their high efficacy, good cycle control, and other health benefits. This method may prove extremely useful over the next 10-20 years. Market surveys will determine whether combined monthly injectables are perceived by potential contraceptive users as having health benefits, and focus group discussions will allow an appropriate range of contraceptive products to be available. These should increase patient choice and allow clinicians to make available a wider range of products for those seeking contraception.

The role of activated protein C resistance in the pathogenesis of venous thrombosis

Venous thromboembolism (VTE) is the third most common cardiovascular disease in the United States. VTE is usually a consequence of either acquired or inherited alterations in hemostatic regulatory proteins. These regulatory proteins are predominantly those of the protein C/protein S natural anticoagulant pathway. Acquired deficiencies in this pathway are frequently a consequence of other clinical entities (eg, cancer, AIDS, and diabetes), while inherited deficiencies can be responsible for venous thrombosis in an otherwise healthy individual. The purpose of this article is to briefly describe the pathobiology of the anticoagulant protein system and to review the clinical implications of activated protein C resistance.

Current reversible contraceptive methods: a global perspective

Since the 1960's, there have been important gains in the efforts to make the benefits of family planning accessible to people around the world. However, prevalence of contraceptive use is still low in some areas, especially in sub-Saharan Africa. Making contraceptives accessible through good quality services should be a goal for reproductive health programs. In the absence of an ideal method of contraception which would suit every individual, there is a variety of contraceptive methods with advantages in some aspects and disadvantages in others from which people should be able to choose according to their particular characteristics and needs. Important aspects to take into consideration include effectiveness, convenience, and safety. In general, the most effective methods are more likely to have some side effects and method-related complications. However, when weighing the risks and benefits, the most effective methods have greater benefits on the health of women by protecting them better from the health risks of unwanted pregnancies. Most methods also have non-contraceptive benefits - for instance, combined oral contraceptives (COCs) provide important degrees of protection against endometrial and ovarian cancers, benign breast disease, pelvic inflammatory disease (PID), and ectopic pregnancy. They also reduce menstrual blood loss. Although barrier methods have lower effectiveness against pregnancy, their most important advantage is the protection they can provide against sexually transmitted diseases. The male condom in particular (and probably the female condom) has the special value of providing protection against HIV infection. This paper describes reversible methods of contraception including possible health risks and contraindications. Adequate counseling, however, is essential for people to make an appropriate choice of contraception and to secure safe and effective use of the method.