Newer oral contraceptives and the risk of venous thromboembolism

Knowledge, Attitude and Practices regarding Contraceptive Pill and Its Side Effects among Women in Jazan Region, Saudi Arabia

Contraception is one of the common methods of family planning. The oral contraceptive pill (OCP) is among the most effective methods of contraception. This study aimed to assess the knowledge, attitude, and practice of oral contraception use and its side effects among women in the Jazan region, Saudi Arabia. A cross-sectional study was carried out among adult women 18 years and older in the Jazan region. A pre-tested questionnaire was used to assess their demographic characteristics, knowledge, attitudes, previous experience, and pattern of OCP usage. Descriptive analysis and a logistic regression model were used to analyse data. About 570 questionnaires were distributed and achieved a 98.3% response rate. The majority of women participants were between 18 and 25 years old, and 51.4% of the respondents reported that they had previously used or were using OCP. We found that women had good knowledge and a positive attitude towards OCP, with more than half of the users preferring them over other contraceptive methods. This study indicates that attitude, knowledge, and prior experience of OCP have no significant effect on the usage pattern of OCP among women with relatively high socioeconomic status in the Jazan region, Saudi Arabia.

Thromboembolic adverse event study of combined estrogen-progestin preparations using Japanese Adverse Drug Event Report database

Combined estrogen-progestin preparations (CEPs) are associated with thromboembolic (TE) side effects. The aim of this study was to evaluate the incidence of TE using the Japanese Adverse Drug Event Report (JADER) database. Adverse events recorded from April 2004 to November 2014 in the JADER database were obtained from the Pharmaceuticals and Medical Devices Agency (PMDA) website (www.pmda.go.jp). We calculated the reporting odds ratios (RORs) of suspected CEPs, analyzed the time-to-onset profile, and assessed the hazard type using Weibull shape parameter (WSP). Furthermore, we used the applied association rule mining technique to discover undetected relationships such as the possible risk factors. The total number of reported cases in the JADER contained was 338,224. The RORs (95% confidential interval, CI) of drospirenone combined with ethinyl estradiol (EE, Dro-EE), norethisterone with EE (Ne-EE), levonorgestrel with EE (Lev-EE), desogestrel with EE (Des-EE), and norgestrel with EE (Nor-EE) were 56.2 (44.3–71.4), 29.1 (23.5–35.9), 42.9 (32.3–57.0), 44.7 (32.7–61.1), and 38.6 (26.3–56.7), respectively. The medians (25%–75%) of the time-to-onset of Dro-EE, Ne-EE, Lev-EE, Des-EE, and Nor-EE were 150.0 (75.3–314.0), 128.0 (27.0–279.0), 204.0 (44.0–660.0), 142.0 (41.3–344.0), and 16.5 (8.8–32.0) days, respectively. The 95% CIs of the WSP-β for Ne-EE, Lev-EE, and Nor-EE were lower and excluded 1. Association rule mining indicated that patients with anemia had a potential risk of developing a TE when using CEPs. Our results suggest that it is important to monitor patients administered CEP for TE. Careful observation is recommended, especially for those using Nor-EE, and this information may be useful for efficient therapeutic planning.

Effect of Age on Oral Contraceptive-Induced Venous Thrombosis

This study was undertaken to investigate the effect of age on oral contraceptive-induced venous thrombosis. All women seen in the University of Padua Department of Medical and Surgical Science who had had two courses of oral contraceptive therapy at different ages were included. A total of 28 subjects met these criteria. Fifteen patients had a congenital or acquired prothrombotic condition, whereas 13 women were normal subjects. The mean age at which thrombosis occurred was 33.3 and 36.3 years for women with or without a prothrombotic condition, respectively. The ages during which the women remained asymptomatic were 23.1 and 23.3 years for women with or without a predisposing defect, respectively. Thrombosis occurred, during the second course of oral contraceptive therapy, after the mean duration of 6.5 cycles or 18.4 cycles in women with or without prothrombotic defects, respectively. During the asymptomatic course, approximately the same number of women took old progestins or third-generation compounds. On the contrary, during the second period, 21 of 28 women took progestins with third-generation compounds. Age seems to plays an important role in oral contraceptive-induced venous thrombosis. In normal women, thrombosis occurred after a greater number of oral contraceptive cycles as compared with the women with prothrombotic defects. Because the majority of women took preparations that contained third-generation progestins during the second course of therapy, concomitant contributing effects of these compounds cannot be excluded.

Instrumental variable analysis as a complementary analysis in studies of adverse effects: venous thromboembolism and second-generation versus third-generation oral contraceptives

PURPOSE

A potentially useful role for instrumental variable (IV) analysis may be as a complementary analysis to assess the presence of confounding when studying adverse drug effects. There has been discussion on whether the observed increased risk of venous thromboembolism (VTE) for third-generation oral contraceptives versus second-generation oral contraceptives could be (partially) attributed to confounding. We investigated how prescribing preference IV estimates compare with conventional estimates.

METHODS

Women in the Clinical Practice Research Database who started a second-generation or third-generation oral contraceptive from 1989 to 2013 were included. Ordinary least squares and two-stage least squares regression were used to estimate risk differences in VTE. Cox regression and IV for Cox proportional hazards regression were used to calculate hazard ratios (HR). The instrument used was the proportion of prescriptions for third-generation oral contraceptives by the general practitioner in the year preceding the current prescription.

RESULTS

All analyses pointed in the direction of an increased VTE risk for third-generation oral contraceptives. The adjusted HR from the conventional Cox regression was 1.62 (95% confidence interval 1.16-2.27) and the fully adjusted HR from the IV Cox regression was 3.45 (95% confidence interval; 0.97-11.7), showing a larger risk and wider confidence intervals in the IV analysis.

CONCLUSIONS

The similarity in direction of results from the IV analyses and conventional analyses suggests that major confounding is unlikely. IV analysis can be a useful complementary analysis to assess the presence of confounding in studies of adverse drug effects in very large databases.

Oral contraceptives and the periodontium

Oral contraceptives are a safe and effective means of contraception for millions of women worldwide. The first formulations of these drugs contained much higher doses of estrogens and progestins than those available today, and these were associated with an unacceptably high rate of unwanted effects including serious cardiovascular events. In addition, a number of case reports and clinical studies suggested that use of the first generation oral contraceptives was also associated with an increased risk for gingival and/or periodontal disease. Unfortunately, many of these early studies suffered from significant methodological flaws which throw their findings into question. Nonetheless, these studies provided the basis for a perception among the dental profession that oral contraceptives increase the risk for gingivitis and/or periodontitis. Realisation that the adverse events profile of oral contraceptives was dose dependant led to the development of the modern low dose formulations that are in use today. There have been far fewer studies to investigate whether modern oral contraceptives have any impact on the periodontium compared to studies of the early contraceptive formulations, but the quality of the more recent research is undoubtedly better. Following extensive review of the relevant literature and consideration of the historical perspective, the best available evidence strongly supports that oral contraceptives no longer place users at any increased risk for gingivitis or periodontitis. Oral contraceptives should not be viewed as a risk factor for gingival or periodontal disease.

A pathway to improved prospective observational post-authorization safety studies

Randomized controlled trials (RCTs) are the gold standard for assessing the efficacy of drugs but not necessarily so for drug safety where inadequate power to detect either multiple or rare adverse events is a major handicap. Furthermore, the conditions under which drugs are approved for market use are often different from the settings in actual use. Indeed, with their control mechanisms, trials are by design largely inadequate for the identification of potential safety signals, especially of the rare type, hence the value of postmarketing surveillance and risk management plan-based activities. Today, clinical trials constitute only a part of the research that goes into assessing the safety of drugs. Observational studies, where the investigators merely collect data on treatments received by patients and their health status in routine clinical practice are increasing in uptake because they reflect the real-life utility of drugs, despite the absence of random treatment assignment. Although such studies generally provide less compelling evidence than RCTs, they can be far more useful to drug safety assessment activities than generally acknowledged. An increasing number of post-authorization safety studies (PASS) within the European Medicines Agency's jurisdiction are of the observational type - considered perhaps as more appropriate vehicles for exploring and documenting how products perform in the real world. A similar trend is emerging in the US following the FDA Amendments Act of 2007; since early 2010, an increasing number of post-approval commitments mandated by the FDA include observational studies. However, despite this pattern, not much is known about ongoing efforts to address many of the recognized inadequacies associated with existing methodologies and practices currently adopted in observational PASS. This current opinion presents an overview of some of the main challenges we face in prospective observational PASS, mainly from practical experience, and proposes certain steps for improvement.

Venous thrombosis and oral contraceptives: current status

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

The new extended-cycle levonorgestrel-ethinyl estradiol oral contraceptives

Effective contraceptive counseling requires an understanding of a woman's preferences and medical history as well as the risks, benefits, side effects, and contraindications of each contraceptive method. Hormonal contraceptives using a variety of delivery methods are highly effective and this review highlights the new extended-cycle levonorgestrel-ethinyl estradiol contraceptives. Extended-cycle OCPs are unique in offering fewer or no withdrawal bleeds over the course of one year but providers need to carefully counsel women regarding the initial increased breakthrough bleeding. Extended-cycle OCPs may be of particular benefit in women with medical comorbidities who would benefit from less withdrawal bleeds, those desiring to avoid monthly menses due to increased hormonal withdrawal symptoms, or simply women who don't desire a monthly period. The risks associated with all extended-cycle OCPs have been found to be similar to those of traditional OCPs therefore counseling on the risks and side effects is comparable to that of any combined hormonal contraceptives. Newer extended-cycle regimens shorten or eliminate the hormone-free interval, decrease frequency of menses to four times per year or eliminate menses altogether. This can reduce the risk of common menstrual symptoms, endometriosis, or severe dysmenorrhea by offering potentially greater ovarian suppression and preventing endogenous estradiol production while still providing highly effective, rapidly reversible, and safe contraception.

The venous thrombotic risk of oral contraceptives, effects of oestrogen dose and progestogen type: results of the MEGA case-control study

OBJECTIVE

To assess the thrombotic risk associated with oral contraceptive use with a focus on dose of oestrogen and type of progestogen of oral contraceptives available in the Netherlands.

DESIGN

Population based case-control study.

SETTING

Six participating anticoagulation clinics in the Netherlands (Amersfoort, Amsterdam, The Hague, Leiden, Rotterdam, and Utrecht).

PARTICIPANTS

Premenopausal women <50 years old who were not pregnant, not within four weeks postpartum, and not using a hormone excreting intrauterine device or depot contraceptive. Analysis included 1524 patients and 1760 controls.

MAIN OUTCOME MEASURES

First objectively diagnosed episodes of deep venous thrombosis of the leg or pulmonary embolism. Odds ratios calculated by cross-tabulation with a 95% confidence interval according to Woolf's method; adjusted odds ratios estimated by unconditional logistic regression, standard errors derived from the model.

RESULTS

Currently available oral contraceptives increased the risk of venous thrombosis fivefold compared with non-use (odds ratio 5.0, 95% CI 4.2 to 5.8). The risk clearly differed by type of progestogen and dose of oestrogen. The use of oral contraceptives containing levonorgestrel was associated with an almost fourfold increased risk of venous thrombosis (odds ratio 3.6, 2.9 to 4.6) relative to non-users, whereas the risk of venous thrombosis compared with non-use was increased 5.6-fold for gestodene (5.6, 3.7 to 8.4), 7.3-fold for desogestrel (7.3, 5.3 to 10.0), 6.8-fold for cyproterone acetate (6.8, 4.7 to 10.0), and 6.3-fold for drospirenone (6.3, 2.9 to 13.7). The risk of venous thrombosis was positively associated with oestrogen dose. We confirmed a high risk of venous thrombosis during the first months of oral contraceptive use irrespective of the type of oral contraceptives.

CONCLUSIONS

Currently available oral contraceptives still have a major impact on thrombosis occurrence and many women do not use the safest brands with regard to risk of venous thrombosis.

Helping women choose appropriate hormonal contraception: update on risks, benefits, and indications

Primary care physicians frequently provide contraceptive counseling to women who are interested in family planning, have medical conditions that may be worsened by pregnancy, or have medical conditions that necessitate the use of potentially teratogenic medications. Effective counseling requires up-to-date knowledge about hormonal contraceptive methods that differ in hormone dosage, cycle length, and hormone-free intervals and are delivered by oral, transdermal, transvaginal, injectable, or implantable routes. Effective counseling also requires an understanding of a woman's preferences and medical history as well as the risks, benefits, side effects, and contraindications of each contraceptive method. This article is designed to update physicians on this information.

Study of low-density lipoprotein receptor regulation by oral (steroid) contraceptives: desogestrel, levonorgestrel and ethinyl estradiol in JEG-3 cell line and placental tissue

BACKGROUND

The aim of this study was to compare in vitro the role of two oral contraceptives, desogestrel (a less androgenic derivative of levonorgestrel) and levonorgestrel--alone and in combination with ethinyl estradiol--on low-density lipoprotein (LDL) receptor regulation by assessing receptor protein expression and functional effectiveness.

STUDY DESIGN

Placental tissue and cultured placental cells (JEG-3) were used to study the expression and endocytotic activity of LDL receptor protein. The expression of the receptor was assessed by immunocytochemistry and immunoblot assays with and without contraceptive challenge. Functioning activity of LDL receptor was studied by measuring the rate of uptake of LDL by placental cells. Quantification of LDL was based on the total cholesterol content of the lipoprotein.

RESULTS

A combination of desogestrel (20 ng/mL of incubation medium) and ethinyl estradiol (10 ng/mL of incubation medium) maintained the LDL receptor at high level of expression and functioning mode. In contrast, the double-blind preparation of levonorgestrel (20 ng/mL) and ethinyl estradiol (10 ng/mL) had shown much lower expression as well as receptor-mediated LDL uptake. The concentration of contraceptives used in this study was similar to the prevailing concentration of oral contraceptives in clinical use.

CONCLUSION

Higher expression of LDL receptor and enhanced rate of LDL uptake by the receptor protein projects the possibility that there might be less atherosclerosis-related disorders from the combination of desogestrol and ethinyl estradiol.

Evaluation of iron deficiency in young women in relation to oral contraceptive use

BACKGROUND

The purpose of this study was to identify the optimal measures for diagnosing iron deficiency (ID) in oral contraceptive (OC) users and nonusers, and to estimate ID frequency in relation to OC use.

STUDY DESIGN

Conventional biomarkers of iron status - serum ferritin, iron, transferrin (Tf) and transferrin saturation (TfS) - were compared with serum soluble Tf receptor (sTfR) and the sTfR/log ferritin ratio (sTfR-F index). Two hundred two healthy menstruating white Italian women (aged 24+/-4.8 years) were analyzed. Serum ferritin concentrations <12 microg/L were considered as ID.

RESULTS

ID was detected in 29.7% (60/202) of the study women. Fifty-nine women were OC users (59/202, 29.2%). OC use did not significantly affect ID prevalence (p=.24). However, OC use markedly increased Tf in OC users, who had an odds ratio (OR) of 9.3 (CI 3.8-22.7, p<.001) for elevated Tf >330 mg/dL. No other iron status measure was affected by OC. Of the markers for ID adjunctive to ferritin, an elevated sTfR-F index >or =1.5 showed the best performance. Specifically in OC users, the elevated sTfR-F index had better sensitivity (81.0% vs. 33.3%), specificity (94.7% vs. 92.1%), efficiency (89.8% vs. 71.2%), positive predictive value (89.5% vs. 70.0%) and negative predictive value (90.0% vs. 71.1%) than a TfS <15%. Additionally, the sTfR-F index allowed the identification of low iron stores in 4.5% (9/202) of women with ferritin > or =12 microg/L.

CONCLUSION

Among healthy OC users and non-OC users, the sTfR-F index had the highest performance for diagnosing ID compared with other serum markers adjunctive to ferritin measurements, whereas sTfR by itself had a low sensitivity. We showed that neither the sTfR nor sTfR-F index was affected by third-generation OC use. The sTfR measurement is useful in the diagnosis of ID, especially in women using OC, where Tf and TfS tests may be misleading.

Developments in post-marketing comparative effectiveness research

Physicians and insurers need to weigh the effectiveness of new drugs against existing therapeutics in routine care to make decisions about treatment and formularies. Because Food and Drug Administration (FDA) approval of most new drugs requires demonstrating efficacy and safety against placebo, there is limited interest by manufacturers in conducting such head-to-head trials. Comparative effectiveness research seeks to provide head-to-head comparisons of treatment outcomes in routine care. Health-care utilization databases record drug use and selected health outcomes for large populations in a timely way and reflect routine care, and therefore may be the preferred data source for comparative effectiveness research. Confounding caused by selective prescribing based on indication, severity, and prognosis threatens the validity of non-randomized database studies that often have limited details on clinical information. Several recent developments may bring the field closer to acceptable validity, including approaches that exploit the concepts of proxy variables using high-dimensional propensity scores, within-patient variation of drug exposure using crossover designs, and between-provider variation in prescribing preference using instrumental variable (IV) analyses.

Sensitivity analysis and external adjustment for unmeasured confounders in epidemiologic database studies of therapeutics

BACKGROUND

Large health care utilization databases are frequently used to analyze unintended effects of prescription drugs and biologics. Confounders that require detailed information on clinical parameters, lifestyle, or over-the-counter medications are often not measured in such datasets, causing residual confounding bias.

OBJECTIVE

This paper provides a systematic approach to sensitivity analyses to investigate the impact of residual confounding in pharmacoepidemiologic studies that use health care utilization databases.

METHODS

Four basic approaches to sensitivity analysis were identified: (1) sensitivity analyses based on an array of informed assumptions; (2) analyses to identify the strength of residual confounding that would be necessary to explain an observed drug-outcome association; (3) external adjustment of a drug-outcome association given additional information on single binary confounders from survey data using algebraic solutions; (4) external adjustment considering the joint distribution of multiple confounders of any distribution from external sources of information using propensity score calibration.

CONCLUSION

Sensitivity analyses and external adjustments can improve our understanding of the effects of drugs and biologics in epidemiologic database studies. With the availability of easy-to-apply techniques, sensitivity analyses should be used more frequently, substituting qualitative discussions of residual confounding.

Adjusting for Unmeasured Confounders in Pharmacoepidemiologic Claims Data Using External Information

BACKGROUND

Large health care utilization datasets are frequently used to analyze the incidence of rare adverse events from medications. However, possible confounders are typically not measured in such datasets. We show how to assess the impact of confounding by factors not measured in Medicare claims data in a study of the association between selective COX2 inhibitors and acute myocardial infarction (MI).

METHODS

Using the Medicare Current Beneficiary Survey, we assessed the association between use of selective COX2 inhibitors and 5 potential confounders not measured in Medicare claims data: body-mass index, aspirin use, smoking, income, and educational attainment. For 8,785 participants > or =65 years, we estimated the prevalence of selective COX2 inhibitor use and also of each confounder, as well as the association between drug exposure and confounders. Estimates of the confounder-disease associations from the medical literature were used to calculate the extent of residual confounding bias for each potential confounder.

RESULTS

Selective COX2 inhibitor users were less likely to be smokers (8% versus 10%) than nonselective NSAID users, while the prevalence of obesity was comparable (24%). Aspirin use was also balanced among all drug exposure categories. Failure to adjust for 5 potential confounders led to a small underestimation of the association between selective COX2 inhibitors and MI; comparing selective COX2 inhibitors with NSAIDs, the net bias was estimated to be -1.0% of the unknown true effect size (maximum range: -6% to 0%).

CONCLUSIONS

In this example of the relationship between selective COX2 inhibitors and MI, not adjusting for 5 potential confounders in Medicare claims data analyses tended to slightly underestimate the association, but is unlikely to cause important bias.

Effect of four oral contraceptives on hemostatic parameters

This is the first double-blind, controlled, randomized study comparing the effect of different estrogen components in oral contraceptives (OCs) on hemostasis variables. Four groups of 25 women each were treated for six cycles with monophasic combinations containing 21 tablets with either 30 microg ethinylestradiol (EE) + 2 mg dienogest (DNG) (30EE/DNG), 20 microg EE + 2 mg DNG (20EE/DNG), 10 microg EE + 2 mg estradiol valerate (EV) + 2 mg DNG (EE/EV/DNG) or 20 microg EE + 100 microg levonorgestrel (LNG) (EE/LNG). Blood samples were taken on Days 21-26 of the control cycle and on Days 18-21 of the first, third and sixth treatment cycle. Treatment with all four OCs caused an increase in levels of fibrinogen, prothrombin fragment 1+2, D-dimer, plasminogen, plasmin-antiplasmin complex and an increase in protein C activity, a decrease in antithrombin activity, tissue-plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI), and a slight decrease in the sensitivity to activated protein C, but no significant change in that of the thrombin-antithrombin complex. In users of the DNG-containing OCs, the reduction in total and free protein S, and in t-PA and PAI was dependent on the EE dose, while factor VII activity was elevated, but not significantly different from EE/LNG. The results are in agreement with those of previous studies. The effects of EE/EV/DNG on total and free protein S and on t-PA and PAI were lower than those of 20EE/DNG, suggesting that the impact of 2 mg EV on several hemostasis variables is less than that of 10 microg EE. The results show an antagonistic effect of LNG on the EE-induced rise of factor VII activity and fragment 1+2 and on the EE-dependent reduction of total and free protein S.

Sex and gender issues and venous thromboembolism

At least 250,000 episodes of VTE leading to hospitalization or death are estimated to occur in the United States each year. A number of clinical and demographic risk factors for VTE are recognized,with the latter including both age and race. Overall,the incidence of VTE does not appear to vary significantly by sex, as evidenced by a lack of consistency in the magnitude and even direction of effect of sex in a variety of epidemiologic studies of varying design. Several studies have shown a higher incidence among women than men during childbearing age. The issue of a gender effect on the natural history of VTE has not been well studied. The main influence of gender on VTE is the relationship between female gender and several well-recognized clinical risk factors for VTE:oral contraceptive use, hormone replacement therapy, estrogen receptor modulator therapy, and pregnancy. Hormonal therapies are associated with a twofold to threefold increase in VTE incidence. Risk is higher with some formulations than others, during initial use, and among women who are obese, smoke, or have one of several forms of heritable thrombophilia. The pregnant state is associated with a threefold to fivefold increase in VTE risk, and thromboembolism is a major cause of peripartum death. Heritable thrombophilias are also important co-determinants of VTE risk in pregnancy. The mechanisms through which pregnancy and hormonal therapies increase VTE risk have not been definitively established, but hormonal effects on levels of coagulation and anticoagulation factors likely play a role. Venous compression and venous injury also contribute to increased risk during pregnancy and the puerperium. Approaches to diagnosis of VTE in the pregnant woman are largely the same as in the nonpregnant patient, but special treatment considerations do apply. Warfarin is embryopathic, particularly between the 6th and 12th weeks of pregnancy, and should be avoided in favor or heparin or low-molecular weight heparin when treatment of the pregnant woman is necessary. Guidelines have been published to assist the clinician in decision making about prophylaxis of pregnant women at increased risk or pregnancy-related or post-partum VTE.

FFPRHC Guidance (October 2003): First Prescription of Combined Oral Contraception

The Guidance provides information for clinicians on the steps to be taken before providing a woman with her first prescription for combined oral contraception. It updates and replaces previous Faculty Guidance. A key to the grades of recommendations, based on levels of evidence, is given at the end of this document. Details of the methods used by the Clinical Effectiveness Unit (CEU) in developing this Guidance, and evidence tables summarising the research basis of the recommendations, are available on the Faculty website (www.ffprhc.org.uk). Abbreviations used include: blood pressure (BP), body mass (BMI), bone mineral density (BMD), breakthrough bleeding (BTB), British National Formulary (BNF), combined oral contraception (COC), Committee on Safety of Medicines (CSM), confidence interval (CI), deep vein thrombosis (DVT), emergency contraception (EC), ethinyl oestradiol (EE), Faculty Aid to Continuing Professional Development Topics (FACT), Family Planning Association (fpa), follicule-stimulating homone (FSH), general practitioner (GP), intermenstrual bleeding (IMB), luteinising hormone (LT), microgram, myocardial infarction (MI), odds ratio (OR), oral contraception (OC), pulmonary embolism (PE), relative risk (RR), Scottish Intercollegiate Guideline Network (SIGN), sexually transmitted infection (STI), Summary of Product Characteristics (SPCs), venous thomboembolism (VTE), World Health Organization (WHO), WHO Medical Eligibility Criteria (WHOMEC), WHO Selected Practice Recommendations (WHOSPR).

Thrombophilias and gynaecology

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

Changes in prescription patterns of oral contraceptives in a northern Italian province: relation with venous thromboembolism

Oral contraceptives (OC) are a definite risk for venous thrombosis. It is commonly accepted that they cause a fourfold increased risk of thrombosis compared to non-users. The prescription patterns were evaluated from 1990 to 2000 in a northern Italian province (province of Padua). This province is typical of other northern Italian provinces. As a consequence, it can be safely assumed that the observations gathered may apply to the entire north of Italy. During these years, a sharp increase in the use of OC was noted. Furthermore, around 1995 to 1996, a marked switch toward the use of preparations containing third-generation progestins was noted. During the past few years of the observation period, approximately 80% of women use preparations containing third-generation progestins. During the same period, an increased incidence of episodes of venous thromboembolism (VTE) was noted. The increase in the prevalence of VTE episodes appeared to be proportional to the increased use of OC, regardless of the type of progestin contained in the oral contraceptive preparations.

Proposal of a flow chart for thrombosis-free oral contraceptive therapy

Oral contraceptive therapy (OCT) is associated with a fourfold increase in the risk for venous thromboembolism (VTE). Women with congenital defects have a much higher risk. Because it is impossible to screen all women undergoing OCT, it is advisable to adopt some guidelines in an attempt to define the group of women who may be particularly exposed to the risk of VTE. On the basis of experience and that in the literature, two flow charts are used that are simple and reliable. The two flow charts are based on an accurate family and personal history so that an extensive investigation can be carried out only for women who show a positive family or personal history for idiopathic thrombosis. The definition of idiopathic thrombosis may be difficult, particularly in the case of family members. In case of doubt the thrombotic event should be considered as idiopathic. The two flow charts are not intended to eliminate the OCT-related VTE but represent only an attempt to decrease the prevalence of this complication.

Ethinylestradiol/Drospirenone

Ethinylestradiol 30microg/drospirenone 3mg (Yasmin, petibelle) [EE/DRSP] is a combined contraceptive pill (CC) for the prevention of pregnancy in women of reproductive age. Drospirenone is a novel progestogen with antimineralocorticoid, progestogenic and antiandrogenic activity. The theoretical (0-0.07) and corrected (0.41-0.71) Pearl indices and pregnancy ratios (0.3-0.84) in young, healthy women aged 18-35 years (or 18-30 years if smokers) given 13-26 cycles of EE/DRSP in large multi-center trials indicate that this CC is highly effective in preventing pregnancy. EE/DRSP is equally as effective as ethinylestradiol 30microg/desogestrel 150microg (EE/DSG; corrected Pearl index 0.28-0.41) in preventing pregnancy. EE/DRSP is generally well tolerated. The frequency and type of adverse event reported in clinical trials are typical of those observed with other CCs, and comparable to those in women receiving EE/DSG. The incidence of intermenstrual bleeding (spotting, breakthrough bleeding or both) during treatment with EE/DRSP in young, healthy women decreased rapidly after the first cycle to 9 to 18% in the second cycle and 6% after 26 cycles, indicating good cycle control. The incidence of intermenstrual bleeding was similar in recipients of EE/DSG (9 and 14% in cycle 2 and 10% in cycle 26). Bodyweight was maintained +/- 2kg in most young women who received EE/DRSP for up to 26 cycles. Neither EE/DRSP nor EE/DSG showed clinically significant effects on blood pressure. EE/DRSP improved premenstrual and menstrual symptoms (negative affect, water retention, increased appetite) compared with baseline in a noncomparative trial. A similar improvement in skin condition (acne, seborrhea) was observed in women receiving EE/DRSP or ethinylestradiol 35microg/cyproterone acetate 2mg in a randomized, double-blind trial.

CONCLUSIONS

Data from several 1- to 2-year studies show that EE/DRSP is an effective oral contraceptive, with Pearl index values similar to those of established low-dose CCs. This combination is well tolerated, demonstrating good cycle control and a beneficial effect on skin condition and well-being (including some premenstrual and menstrual symptoms). EE/DRSP has demonstrated similar efficacy and tolerability to EE/DSG, but long-term clinical experience is required to establish the position of EE/DRSP among other available CCs and to clarify any potential tolerability advantages. Nevertheless, because the management of tolerability is complicated by the idiosyncratic nature of the response of women to CCs containing different progestogens, EE/DRSP appears to be a useful treatment option for women desiring oral contraception.

Risks and benefits of oral contraceptive pills

In the more than 40 years since the combined oral contraceptive pill was first marketed, much information has been obtained as to its risks. Considerably less publicity has been given to the balancing benefits that have also emerged. There has been an increasing realization that the risks are focused in those women with recognised risk factors, meaning that the remainder can use the product with increasing reassurance. The doses of both hormones have also been lowered considerably since the early years. Thus, it can be a rational decision by a fully informed woman to use this form of contraception.

Tentative guidelines and practical suggestions to avoid venous thromboembolism during oral contraceptive therapy

Oral contraceptive therapy (OCT) is widely used in the world. It is usually safe and effective but side effects are occasionally seen. Venous thromboembolism is one of the most feared side effects. To avoid this complication adequate guidelines are needed. These have to take into account family history, personal history, and suitable laboratory investigations. The presence of an idiopathic venous thrombosis in the family or in the personal history is of paramount importance. However it is often difficult to ascertain whether a venous thrombosis is idiopathic or not. Even when there is doubt, a coagulation study should be carried out. An adequate coagulation study in this case should include at least an evaluation of antithrombin, protein C, and protein S. A search for homozygosity of factor V Leiden appears advisable. These defects represent absolute contraindications to the use of OCT. Relative contraindications may be represented by other minor coagulation disorders such as heterozygous factor V Leiden, fibrinolysis defects, and a G-to-A 20210 prothrombin abnormality. Other noncoagulation-related conditions such as hypertension, liver damage, and obesity may represent absolute or relative contraindications to the use of OCT.

Oral contraceptives and venous thromboembolism: which are the safest preparations available?

Oral contraceptive therapy is associated with a fourfold increased risk of venous thromboembolism as compared with age-matched non-users. The composition of oral contraceptives has varied considerably during the past two to three decades. The estrogen content (ethinylestradiol) has decreased and is now less than 0.03 mg/pill. This was done on the assumption that estrogen was the main culprit for thrombotic complications. Subsequently it was found that the progestins contained in the pill could also play a thrombogenic role. This was particularly maintained to be so for the third-generations progestins, namely gestodene or desogestrel. These gonane progestins have been widely used since the early 1990s, because they appeared to have a lesser androgenic effect. A careful and impartial evaluation of the literature seems to indicate that third-generation progestins are associated with a slight increase in thrombotic risk. However, the significance of this difference remains to be proven. In fact, a relative risk of only two in retrospective studies may have limited effect and disappear in prospectives studies. The role of associated risk factors, both congenital and acquired, has been often overlooked in most of the papers dealing with the subject. This may be important. Preparations containing third-generation progestins are probably associated with a slight increase in thrombosis risk. It is the responsibility of the physician to select the preparation most suited for a given patient. As a general rule it may be safe to start with a preparation containing second-generation progestins. However there is no need for "a pill scare" and it does not seem justified to have women already taking pills containing third-generation progestins to switch to other preparations. If a woman taking preparations containing third-generation progestins experience symptoms, it is probably safe to advise that patient not to take any oral contraceptive pill in the future, regardless of the type. The same is true for women who experience symptoms while taking second-generation progestins preparations.

Oral contraceptives and venous thromboembolism: a five-year national case-control study

The objective of this study was to assess the influence of oral contraceptives (OCs) on the risk of venous thromboembolism (VTE) in young women. A 5-year case-control study including all Danish hospitals was conducted. All women 15-44 years old, suffering a first ever deep venous thrombosis or a first pulmonary embolism (PE) during the period January 1, 1994, to December 30, 1998, were included. Controls were selected annually, 600 per year in 1994-1995 and 1200 per year 1996-1998. Response rates for cases and controls were 87.2% and 89.7%, respectively. After exclusion of nonvalid diagnoses, pregnant women, and women with previous thrombotic disease, 987 cases and 4054 controls were available for analysis. A multivariate, matched analysis was performed. Controls were matched to cases within 1-year age bands. Adjustment was made for confounding influence (if any) from the following variables: age, year, body mass index, length of OC use, family history of VTE, cerebral thrombosis or myocardial infarction, coagulopathies, diabetes, years of schooling, and previous birth. The risk of VTE among current users of OCs was primarily influenced by duration of use, with significantly decreasing odds ratios (OR) over time: <1 year, 7.0 (5.1-9.6); 1-5 years, 3.6 (2.7-4.8); and >5 years, 3.1 (2.5-3.8), all compared with nonusers of OCs. After adjustment for confounders, current use of OCs with second- (levonorgestrel or norgestimate) and third- (desogestrel or gestodene) generation progestins when compared with nonuse resulted in ORs for VTE of 2.9 (2.2-3.8) and 4.0 (3.2-4.9), respectively. After adjusting for progestin types and length of use, the risk decreased significantly with decreasing estrogen dose. With 30-40 microg as reference, 20 and 50 microg products implied ORs of 0.6 (0.4-0.9) and 1.6 (0.9-2.8), respectively (p(trend) = 0.02). After correction for duration of use and differences in estrogen dose, the third/second-generation risk ratio was 1.3 (1.0-1.8; p <0.05). In conclusion, use of OCs was associated significantly to the risk of VTE. The risk among current users was reduced by more than 50% during the first years of use. The risk increased more than 100% with increasing estrogen dose, and the difference in risk between users of third- and second-generation OCs, after correction for length of use and estrogen dose, was 33%.

Female hormones and thrombosis

Exogenous hormones are used by more than a hundred million women worldwide as oral contraceptives or for postmenopausal hormone replacement. Oral contraceptives increase the risk of venous thrombosis, of myocardial infarction, and of stroke. The risk is highest during the first year of use. The venous thrombotic risk of oral contraceptives is high among women with coagulation abnormalities and with so-called third-generation contraceptives (containing desogestrel or gestodene). The risk of myocardial infarction does not appear to depend on coagulation abnormalities or the type of oral contraceptive. Hormone replacement therapy increases the risk of venous thrombosis. This risk is also highest in the first year of use and among women with coagulation abnormalities. The risk becomes very high in women with a previous venous thrombosis. Randomized trials have not confirmed a beneficial effect of postmenopausal hormones on the occurrence of myocardial infarction.

Evaluating the safety of medicines, with particular reference to contraception

Toxicological studies and clinical trials cannot be expected to predict all important adverse effects of medicines and contraceptives. Post-marketing surveillance is essentially an epidemiological task that involves detecting associations between drugs and events. The first alerts about drug safety problems have often come from case reports, but epidemiological studies are needed to confirm adverse (or beneficial) effects and to provide quantitative information. This article illustrates methodological principles by considering three examples from the field of contraceptive safety: oral contraceptives and breast cancer, intrauterine contraception and pelvic inflammatory disease, and newer oral contraceptives and venous thromboembolism. Key issues that emerge include bias and confounding, the place of subgroup analyses, random error, and the use of computerized databases. In research on contraceptive and drug safety, conclusions usually need to be based on careful assessment of multiple observational studies.

Risk of venous thromboembolism from oral contraceptives containing gestodene and desogestrel versus levonorgestrel: a meta-analysis and formal sensitivity analysis

Controversy exists regarding whether oral contraceptives (OCs) containing desogestrel and gestodene are associated with an increased risk of venous thromboembolism (VTE) versus OCs containing levonorgestrel. We were interested in synthesizing the available data, exploring explanations for mixed results, and characterizing the degree of uncontrolled confounding that could have produced a spurious association. We performed a meta-analysis and formal sensitivity analysis of studies that examined the relative risk of VTE for desogestrel and gestodene versus levonorgestrel. Twelve studies, all observational, were included. The summary relative risk (95% CI) was 1.7 (1.3-2.1; heterogeneity p = 0.09). If real, the incremental risk of VTE would be about 11 per 100,000 women per year. An association was present when accounting for duration of use and when restricted to the first year of use in new users. However, in the sensitivity analysis, the association abated in many, but not all, scenarios in which an unmeasured confounding factor increased the risk of VTE three to fivefold and in nearly all examined scenarios in which the factor increased the risk 10-fold. The summary relative risk of 1.7 does not appear to be caused by depletion of susceptibles, but is sensitive to a modest degree of unmeasured confounding. Whether such confounding occurred is unknown. However, given this sensitivity, this issue probably cannot be settled unequivocally with observational data. In the absence of a definitive answer, this apparent increased risk, together with its uncertainty and small magnitude and its important consequences, should be considered when selecting an OC for a given woman.

Third generation oral contraceptives and risk of venous thrombosis: meta-analysis

OBJECTIVE

To evaluate quantitatively articles that compared effects of second and third generation oral contraceptives on risk of venous thrombosis.

DESIGN

Meta-analysis.

STUDIES

Cohort and case-control studies assessing risk of venous thromboembolism among women using oral contraceptives before October 1995.

MAIN OUTCOME MEASURES

Pooled adjusted odds ratios calculated by a general variance based random effects method. When possible, two by two tables were extracted and combined by the Mantel-Haenszel method.

RESULTS

The overall adjusted odds ratio for third versus second generation oral contraceptives was 1.7 (95% confidence interval 1.4 to 2.0; seven studies). Similar risks were found when oral contraceptives containing desogestrel or gestodene were compared with those containing levonorgestrel. Among first time users, the odds ratio for third versus second generation preparations was 3.1 (2.0 to 4.6; four studies). The odds ratio was 2.5 (1.6 to 4.1; five studies) for short term users compared with 2.0 (1.4 to 2.7; five studies) for longer term users. The odds ratio was 1.3 (1.0 to 1.7) in studies funded by the pharmaceutical industry and 2.3 (1.7 to 3.2) in other studies. Differences in age and certainty of diagnosis of venous thrombosis did not affect the results.

CONCLUSIONS

This meta-analysis supports the view that third generation oral contraceptives are associated with an increased risk of venous thrombosis compared with second generation oral contraceptives. The increase cannot be explained by several potential biases.

Knowledge of the risks and benefits associated with oral contraception in a university-aged sample of users and non-users

As research has shown that knowledge concerning the health risks and benefits of oral contraceptive (OC) use is a contributor to OC compliance, the following study examined an educated sample of young women to determine the level of knowledge concerning the risks and benefits of OC use. A 28-item questionnaire was developed by the research team and distributed to female undergraduate students. Five questions were designed to assess the respondent's knowledge of OC. Overall, it found that OC users answered 71.9% of the questions correctly, whereas non-users answered significantly fewer questions correctly. As well, the number of correct responses increased with academic year, indicating that younger women were less knowledgeable about OC. The results of this study indicate that despite increased efforts to educate women, knowledge of OC remains a major problem, even in a sample of women with relatively high socio-economic status.

Preliminary examination of oral contraceptive use among university-aged females

The etymology and use of oral contraceptives (OCs) has greatly influenced the sexual practices and social lives (e.g., decisions concerning childbearing, careers) of adolescent and adult women. In addition, OCs have the potential to benefit or harm its users depending upon the utilization practices and characteristics/lifestyle habits of the women consuming them. A 28-item questionnaire was distributed to female students at a university in Central Ontario and examined: (1) socio-demographic information; (2) background information concerning oral contraceptive use (e.g., length of time taking the pill, concerns about pill use, side effects while on the pill); and (3) procedure for taking the pill (e.g. maximizing effectiveness and safety). Preliminary analysis indicated that females may not be equipped with adequate knowledge or receiving the necessary support to practice the most efficacious behaviours surrounding pill use.

Contraception

The supremacy of combined oral contraceptives (OCs) is being challenged. For too long combined OCs have been seen as synonymous with contraception, helping to maintain ignorance of alternative methods. Further, the efficacy of these OCs and condoms is often compromised by incorrect or inconsistent use. We particularly welcome developments in male systemic methods, that allow men to share not only in conception but also in contraception, and methods that are completely forgettable once instituted, especially if usable by adolescents.

Risk of venous thromboembolism among users of third generation oral contraceptives compared with users of oral contraceptives with levonorgestrel before and after 1995: cohort and case-control analysis

OBJECTIVE

To compare the risk of idiopathic venous thromboembolism among women taking third generation oral contraceptives (with gestodene or desogestrel) with that among women taking oral contraceptives with levonorgestrel.

DESIGN

Cohort and case-control analyses derived from the General Practice Research Database.

SETTING

UK general practices, January 1993 to December 1999.

PARTICIPANTS

Women aged 15-39 taking third generation oral contraceptives or oral contraceptives with levonorgestrel.

MAIN OUTCOME MEASURES

Relative incidence (cohort study) and odds ratios (case-control study) as measures of the relative risk of venous thromboembolism.

RESULTS

The adjusted estimates of relative risk for venous thromboembolism associated with third generation oral contraceptives compared with oral contraceptives with levonorgestrel was 1.9 (95% confidence interval 1.3 to 2.8) in the cohort analysis and 2.3 (1.3 to 3.9) in the case-control study. The estimates for the two types of oral contraceptives were similar before and after the warning issued by the Committee on Safety of Medicines in October 1995. A shift away from the use of third generation oral contraceptives after the scare was more pronounced among younger women (who have a lower risk of venous thromboembolism) than among older women. Fewer cases of venous thromboembolism occurred in 1996 and later than would have been expected if the use of oral contraceptives had remained unchanged.

CONCLUSIONS

These findings are consistent with previously reported studies, which found that compared with oral contraceptives with levonorgestrel, third generation oral contraceptives are associated with around twice the risk of venous thromboembolism.

Occlusive vascular diseases in oral contraceptive users. Epidemiology, pathology and mechanisms

Despite being an unprecedented departure from normal physiology, the combined oral contraceptive is not only highly effective, but it also has a remarkably good safety record. Concerns over safety persist, though, particularly with regard to venous thromboembolism (VTE), stroke and myocardial infarction (MI). Epidemiological studies consistently show an increase in risk of VTE, but the results are more contentious with regard to arterial diseases. Despite 40 years of research, the mechanisms behind these adverse effects are not understood. In this review, we integrate information from published studies of the epidemiology and pathology of the occlusive vascular diseases and their risk factors to identify likely explanations for pathogenesis in oral contraceptive users. Oral contraceptives induce both prothrombotic and fibrinolytic changes in haemostatic factors and an imbalance in haemostasis is likely to be important in oral contraceptive-induced VTE. The complexity of the changes involved and the difficulty of ascribing clinical significance has meant that uncertainty persists. A seriously under-researched area concerns vascular changes in oral contraceptive users. Histologically, endothelial and intimal proliferation have been identified in women exposed to high plasma estrogen concentrations and these lesions are associated with thrombotic occlusion. Other structural changes may result in increased vascular permeability, loss of vascular tone and venous stasis. With regard to arterial disease risk, epidemiological information relating to dose effects and joint effects with other risk factors, and studies of pathology and changes in risk factors, suggests that oral contraceptive use per se does not cause arterial disease. It can, nevertheless, synergise very powerfully with subclinical endothelial damage to promote arterial occlusion. Accordingly, the prothrombotic effects of the oral contraceptive estrogen intervene in a cycle of endothelial damage and repair which would otherwise remain clinically silent or would ultimately progress - in, for example, the presence of cigarette smoking or hypertension - to atherosclerosis. Future work in this area should focus on modification of the effects of established risk factors by oral contraceptive use rather than modification of the supposed risk of oral contraceptive use by established risk factors. Attempts to understand vascular occlusion in oral contraceptive users in terms of the general features of VTE or with reference to atherosclerosis may be limiting, and future work needs to acknowledge that such occlusions may have unique features. Unequivocal identification of the mechanisms involved would contribute considerably to the alleviation of fears over vascular disease and to the development of even safer formulations.

Oral contraceptives and thrombosis

Oral contraceptives (OCs) are used by many millions of healthy young women. Their ease of use and efficacy against unwanted pregnancy has made them an indispensable part of modern society. Despite various changes in formulation, they are clearly associated with an increased risk of venous thromboembolism (VTE). Case-control and prospective studies have developed a range of relative risks of VTE, but the important issue is the impact of VTE relative to perceived benefits of the OC. This involves societal as well as medical judgment. The development of third-generation OCs has led to considerable concerns that these newer preparations may be associated with additional thrombotic risks over and above those of the traditional second-generation preparations. The paradoxical effect, that a change in progestogen in the combined OC could lead to increased VTE, could be explained by the induction of activated protein C resistance. In a society that is less prepared to accept unwanted side effects from medications, it is recommended that increased attention be given to patient selection, and possibly the incorporation into this process of some of the more recently discovered hypercoagulability markers.

Oral contraceptives and fatal pulmonary embolism

In a national case-control study of fatal pulmonary embolism in New Zealand women of childbearing age, we estimated that current users of combined oral contraceptives had a relative risk of 9.6 (95% CI 3.1-29.1). From national distribution data, the absolute risk of death from pulmonary embolism in current users was estimated to be 10.5 per million woman-years.

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.

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.

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.

A multicenter randomized comparison of cycle control and laboratory findings with oral contraceptive agents containing 100 microg levonorgestrel with 20 microg ethinyl estradiol or triphasic norethindrone with ethinyl estradiol

OBJECTIVE

This study was undertaken to compare the effects of 2 oral contraceptive regimens on menstrual cycle control and laboratory findings.

METHODS

In a multicenter randomized study 100 microg levonorgestrel with 20 microg ethinyl estradiol (Alesse or Loette) was given to 155 healthy women. A triphasic preparation of 500, 750, and 1000 microg norethindrone with 35 microg ethinyl estradiol (Ortho-Novum 7/7/7 or TriNovum) was given to 167 women for 1 to 4 cycles of treatment.

RESULTS

Overall, the percentages of normal menstrual cycles and the percentages of cycles with intermenstrual and withdrawal bleeding were similar between the 2 treatment groups. In the levonorgestrel with ethinyl estradiol group, there was a statistically significantly longer latent period and a statistically significantly shorter withdrawal bleeding episode. Adverse events were similar between treatment groups, and none were serious. Most mean changes from baseline laboratory values were comparable between groups, although the mean increase in cholesterol concentration was statistically significantly lower in the levonorgestrel with ethinyl estradiol group. Changes in triglyceride and glucose concentrations were not statistically significantly different between groups.

CONCLUSIONS

Levonorgestrel (100 microg) with ethinyl estradiol (20 microg) provides menstrual cycle control equivalent to that obtained with triphasic norethindrone with ethinyl estradiol (75% higher estrogen dose) with similar safety and tolerability.