Cycle control with a 21-day compared with a 24-day oral contraceptive pill: a randomized controlled trial

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

OBJECTIVE

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

OUTCOMES

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

EVIDENCE

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

VALUES

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

SUMMARY STATEMENTS

RECOMMENDATIONS.

Combined hormonal contraceptives for heavy menstrual bleeding

BACKGROUND

Menorrhagia or heavy menstrual bleeding (HMB) is an excessive blood loss that impairs a woman's quality of life, either physical, emotional, social or material. It is benign and not associated with pregnancy or any other gynaecological or systemic disease. Medical treatments used to reduce excessive menstrual blood loss (MBL) include prostaglandin synthetase inhibitors, antifibrinolytics, oral contraceptive pills, and other hormones. The combined oral contraceptive pill (COCP) is claimed to have a variety of beneficial effects, inducing a regular shedding of a thinner endometrium and inhibiting ovulation, thus having the effect of both treating HMB and providing contraception. More recently, a contraceptive vaginal ring (CVR) has been trialled to investigate whether this treatment can provide similar benefits to COCP while lessening hormonal systemic exposure. This review is an update of a review which originally focused on COCP alone. The scope of the review has been widened to consider other types of delivery of combined hormonal contraceptives for reduction of MBL.

OBJECTIVES

To determine the efficacy of combined hormonal contraceptives (pills, vaginal ring or patch) compared with other medical therapies, placebo, or no therapy in the treatment of HMB. A secondary objective was to compare the COCP with the CVR.

SEARCH METHODS

We searched the Gynecology and Fertility Group trials register, MEDLINE, Embase, CENTRAL, CINAHL and PsycINFO (search dates: Oct 1996, May 2002, June 2004, April 2006, June 2009, July 2017 and September 2018) for all randomised controlled trials (RCTs) of COCP and CVR for the treatment of HMB. We also searched trial registers and the reference lists of retrieved studies for additional trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of the use of COCP or CVR compared with no treatment, placebo, or other medical therapies for women with HMB and regular menstrual cycles.

DATA COLLECTION AND ANALYSIS

All assessments of trial quality and data extraction were performed unblinded by at least two review authors. Our primary review outcomes were treatment success, menstrual bleeding (assessed objectively, semi-objectively or subjectively), and participant satisfaction with treatment. Secondary outcomes were adverse events, quality of life, and haemoglobin level.

MAIN RESULTS

We identified eight RCTs involving 805 participants. Two trials comparing COCP with placebo were considered to be moderate quality and the remaining studies were low to very low quality, mainly because of serious risk of bias from lack of blinding and concerns over precision.COCP versus placeboCOCP, with a step-down oestrogen and step-up progestogen regimen, improved response to treatment (return to menstrual 'normality') (OR 22.12, 95% CI 4.40 to 111.12; 2 trials; 363 participants; I² = 50%; moderate-quality evidence), and lowered MBL (OR 5.15, 95% CI 3.16 to 8.40; 2 trials; 339 participants; I² = 0%; moderate-quality evidence) when compared to placebo. The results suggested that, if the chance of 'successful' treatment was 3% in women taking placebo, then COCP increased this chance from 12% to 77% in women with unacceptable HMB. Minor adverse events, in particular breast pain, were more common with COCP. No study in this comparison reported semi-objectively assessed MBL or participant satisfaction with treatment.COCP versus other medical treatmentsNon-steroidal anti-inflammatory drugs (NSAIDs)There was insufficient evidence to determine whether the COCP reduced MBL when compared to NSAIDs (mefenamic acid and naproxen). No study in this comparison reported semi-objectively assessed MBL, subjectively assessed MBL, participant satisfaction with treatment or adverse events.Levonorgestrel-releasing intrauterine system (LNG IUS)The LNG IUS was more effective than COCP in reducing MBL (OR 0.21, 95% CI 0.09 to 0.48; 2 trials; 151 participants; I² = 0%; low-quality evidence) but it was not clear whether satisfaction with treatment or adverse effects varied according to which treatment was used. No study in this comparison reported semi-objectively assessed MBL or subjectively assessed MBL.Contraceptive vaginal ring (CVR) versus other medical treatmentsCOCP COCP was compared with CVR in two trials. There were discrepancies between some of the findings and there was no evidence of a benefit for one treatment compared to the other for response to treatment, MBL or participant satisfaction with treatment. There was a greater likelihood of nausea with COCP. No study in this comparison reported objectively assessed MBL or subjectively assessed MBL.ProgestogensCVR was compared to long course progestogens in one trial. It is possible that CVR increased the odds of satisfaction; but we are uncertain whether CVR improved MBL. The evidence was based on small numbers of participants and was very low quality, so definitive conclusions could not be reached. No study in this comparison reported objectively assessed MBL, subjectively assessed MBL, or adverse events.

AUTHORS' CONCLUSIONS

Moderate-quality evidence suggests that the combined oral contraceptive pill over six months reduces HMB in women with unacceptable HMB from 12% to 77% (compared to 3% in women taking placebo). When compared with other medical options for HMB, COCP was less effective than the LNG IUS. Limited evidence suggested that COCP and CVR had similar effects. There was insufficient evidence to determine comparative efficacy of combined hormonal contraceptives with NSAIDs, or long course progestogens.

The medical management of abnormal uterine bleeding in reproductive-aged women

In the treatment of women with abnormal uterine bleeding, once a thorough history, physical examination, and indicated imaging studies are performed and all significant structural causes are excluded, medical management is the first-line approach. Determining the acuity of the bleeding, the patient's medical history, assessing risk factors, and establishing a diagnosis will individualize their medical regimen. In acute abnormal uterine bleeding with a normal uterus, parenteral estrogen, a multidose combined oral contraceptive regimen, a multidose progestin-only regimen, and tranexamic acid are all viable options, given the appropriate clinical scenario. Heavy menstrual bleeding can be treated with a levonorgestrel-releasing intrauterine system, combined oral contraceptives, continuous oral progestins, and tranexamic acid with high efficacy. Nonsteroidal antiinflammatory drugs may be utilized with hormonal methods and tranexamic acid to decrease menstrual bleeding. Gonadotropin-releasing hormone agonists are indicated in patients with leiomyoma and abnormal uterine bleeding in preparation for surgical interventions. In women with inherited bleeding disorders all hormonal methods as well as tranexamic acid can be used to treat abnormal uterine bleeding. Women on anticoagulation therapy should consider using progestin-only methods as well as a gonadotropin-releasing hormone agonist to treat their heavy menstrual bleeding. Given these myriad options for medical treatment of abnormal uterine bleeding, many patients may avoid surgical intervention.

Extended regimen combined oral contraception: A review of evolving concepts and acceptance by women and clinicians

Objectives: The clinical utility of extended regimen combined oral contraceptives (COCs) is increasingly being recognised. Our objective was to understand the attitudes of women and clinicians about the use of these regimens. We present the rationale for extended regimen COCs from a historical perspective, and trace their evolution and growing popularity in light of their clinical benefits. We conclude by offering potential strategies for counselling women about extended regimen COC options.

Methods: We conducted a MEDLINE search to identify and summarise studies of extended regimen COCs, focusing on attitudes of women and clinicians regarding efficacy, safety/tolerability and fewer scheduled bleeding episodes and other potential benefits.

Results: The body of contemporary literature on extended regimen COCs suggests that their contraceptive efficacy is comparable to that of conventional 28-day (i.e., 21/7) regimens. For women seeking contraception that allows infrequent scheduled bleeding episodes, particularly those who suffer from hormone withdrawal symptoms and cyclical symptoms (e.g., headache, mood changes, dysmenorrhoea, heavy menstrual bleeding), extended regimen COCs are an effective and safe option. Although satisfaction with extended regimen COCs in clinical trials is high, misperceptions about continuous hormone use may still limit the widespread acceptance of this approach.

Conclusions: Despite the widespread acceptance among clinicians of extended regimen COCs as an effective and safe contraceptive option, these regimens are underused, likely due to a lack of awareness about their availability and utility among women. Improved patient education and counselling regarding the safety and benefits of extended regimen COCs may help women make more informed contraceptive choices.

The shorter, the better: A review of the evidence for a shorter contraceptive hormone-free interval

OBJECTIVES

The menstrual cycle is characterised by cyclical fluctuations in oestrogens, progesterone and androgens. Changes in hormone levels in the premenstrual phase with the decline in progesterone trigger a physiological reaction which culminates in menstruation. This process is accompanied in many women by various symptoms such as pelvic pain, headache, mood disorders and gastrointestinal discomfort. The aim of this article was to summarise the latest findings on the physiology and pathophysiology of menstruation and review the impact of shortening the hormone-free interval (HFI) on the health and wellbeing of women.

RESULTS

Menstruation can be viewed as an inflammatory event in which local and systemic effects produce symptoms in genital and extragenital regions of the body. The mast cells are the main mediator of this reaction. In women using hormonal contraceptives, menstrual bleeding is not biologically necessary and it may be advantageous to maintain more stable levels of oestrogens, progesterone and androgens throughout the cycle. New combined oral contraceptives (COCs) have been formulated with a progressively shorter HFI (24/4 and 26/2) than traditional 21/7 pills, with the rationale of reducing hormone withdrawal- associated symptoms. Several studies have shown the beneficial effects of these regimens, which reduce the inflammatory exposure of the female organism and thus have the capacity to increase the quality of life of women. A combination of estradiol valerate (E2V) and dienogest (DNG) is administered on the shortest 26/2 regimen. This regimen has a broad evidence base from randomised controlled trials that have examined the impact of E2V/DNG on symptoms and quality of life.

CONCLUSIONS

Shortening the HFI reduces the occurrence of bleeding-related inflammatory processes and subsequent physical and mental symptoms. The shortest interval with evidence of reproductive and sexual health benefits is provided by a 26/2 regimen.

The combined oral contraceptive pill -- recent developments, risks and benefits

The introduction of the birth control pill as an effective, coitally-independent method of contraception was a public health milestone of the last century. Over time, combined oral contraception (COC) formulations and pill-taking regimens have evolved with improved safety and tolerability while maintaining contraceptive efficacy. In addition to protection against pregnancy, use of combined oral contraception confers a number of significant non-contraceptive benefits to users. COC use is also associated with well-studied risks. Common side effects are generally self-limiting and improve with increasing duration of use while serious adverse events, including venous thromboembolism, are rare among healthy COC users. Contraceptive decision-making should include consideration of both the risks and benefits of a given method versus the real consequences of unintended pregnancy.

20 µg versus >20 µg estrogen combined oral contraceptives for contraception

BACKGROUND

Concern about estrogen-related adverse effects has led to progressive reductions in the estrogen dose in combination oral contraceptives (COCs). However, reducing the amount of estrogen to improve safety could result in decreased contraceptive effectiveness and unacceptable changes in bleeding patterns.

OBJECTIVES

To test the hypothesis that COCs containing ≤ 20 μg ethinyl estradiol (EE) perform similarly as those containing > 20 μg in terms of contraceptive effectiveness, bleeding patterns, discontinuation, and side effects.

SEARCH METHODS

In July 2013, we searched CENTRAL, MEDLINE, and POPLINE, and examined references of potentially eligible trials. We also searched for recent clinical trials using ClinicalTrials.gov and ICTRP. No new trials met the inclusion criteria. Previous searches included EMBASE. For the initial review, we wrote to oral contraceptive manufacturers to identify trials.

SELECTION CRITERIA

English-language reports of randomized controlled trials were eligible that compare a COC containing ≤ 20 μg EE with a COC containing > 20 μg EE. We excluded studies where the interventions were designed to be administered for less than three consecutive cycles or to be used primarily as treatment for non-contraceptive conditions. Trials had to report on contraceptive effectiveness, bleeding patterns, trial discontinuation due to bleeding-related reasons or other side effects, or side effects to be included in the review.

DATA COLLECTION AND ANALYSIS

One author evaluated all titles and abstracts from literature searches to determine whether they met the inclusion criteria. Two authors independently extracted data from studies identified for inclusion. We wrote to the researchers when additional information was needed. Data were entered and analyzed with RevMan.

MAIN RESULTS

No differences were found in contraceptive effectiveness for the 13 COC pairs for which this outcome was reported. Compared to the higher-estrogen pills, several COCs containing 20 μg EE resulted in higher rates of early trial discontinuation (overall and due to adverse events such as irregular bleeding) as well as increased risk of bleeding disturbances (both amenorrhea or infrequent bleeding and irregular, prolonged, frequent bleeding, or breakthrough bleeding or spotting).

AUTHORS' CONCLUSIONS

While COCs containing 20 μg EE may be theoretically safer, this review did not focus on the rare events required to assess this hypothesis. Data from existing randomized controlled trials are inadequate to detect possible differences in contraceptive effectiveness. Low-dose estrogen COCs resulted in higher rates of bleeding pattern disruptions. However, most trials compared COCs containing different progestin types, and changes in bleeding patterns could be related to progestin type as well as estrogen dose. Higher follow-up rates are essential for meaningful interpretation of results.

A historical cycle control comparison of two drospirenone-containing combined oral contraceptives: ethinylestradiol 30 μg/drospirenone 3 mg administered in a 21/7 regimen versus ethinylestradiol 20 μg/drospirenone 3 mg administered in a 24/4 regimen

OBJECTIVES

To compare the bleeding patterns and cycle control of an oral contraceptive (OC) containing ethinylestradiol (EE) 30 μg/drospirenone (drsp) 3mg administered in a 21/7 regimen versus a lower-dose OC containing EE 20 μg/drsp 3mg administered in a 24/4 regimen, using data from two identically designed studies.

MATERIALS AND METHODS

In the first study, 326 healthy women (18-35 years) received EE 30 μg/drsp 3mg in a 21/7 regimen. In the second study, 1027 healthy women (17-36 years) received EE 20 μg/drsp 3mg in a 24/4 regimen. Participants recorded bleeding using daily completed diaries over 13 treatment cycles.

RESULTS

During cycles 1-12, the prevalence of scheduled withdrawal bleeding was lower with EE 20 μg/drsp 3mg 24/4 than with EE 30 μg/drsp 3mg 21/7 (82.0-91.7% versus 94.8-100.0% of women, respectively); moreover, a higher proportion of women reported a maximum intensity of light scheduled withdrawal bleeding with EE 20 μg/drsp 3mg 24/4 than with EE 30 μg/drsp 3mg 21/7 (30.9-39.0% versus 13.8-20.5% of women, respectively). In cycles 2-13, unscheduled intracyclic bleeding was reported by 7.7-13.8% of EE 20 μg/drsp 3mg 24/4 recipients and 3.8-7.9% of EE 30 μg/drsp 3mg 21/7 recipients; these were mainly single bleeding days. During reference periods 1-4, the mean number of bleeding episodes was similar between groups (3.1-3.3 episodes with EE 20 μg/drsp 3mg 24/4 versus 3.2 episodes with EE 30 μg/drsp 3mg 21/7).

CONCLUSIONS

A low-dose 24/4 regimen OC containing EE 20 μg/drsp 3mg is generally comparable in terms of bleeding to a higher-dose 21/7 regimen OC containing EE30 μg/drsp 3mg. Between-treatment differences in bleeding intensity and unscheduled intracyclic bleeding rates were observed.

Triphasic versus monophasic oral contraceptives for contraception

BACKGROUND

Side effects of oral contraceptive (OC) pills discourage adherence to and continuation of OC regimens. Strategies to decrease adverse effects led to the introduction of the triphasic OC in the 1980s. Whether triphasic OCs have higher accidental pregnancy rates than monophasic pills is unknown. Nor is it known if triphasic pills give better cycle control and fewer side effects than the monophasic pills.

OBJECTIVES

To compare triphasic OCs with monophasic OCs in terms of efficacy, cycle control, and discontinuation due to side effects.

SEARCH METHODS

We searched the computerized databases of the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, POPLINE, EMBASE, and LILACS, as well as clinical trials databases (ClinicalTrials.gov and the World Health Organization Clinical Trials Registry Platform (ICTRP)) in May 2011. Additionally, we searched the reference lists of relevant articles. We also contacted researchers and pharmaceutical companies to identify other trials not found in our search.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing any triphasic OC with any monophasic pill used to prevent pregnancy. Interventions had to include at least three treatment cycles.

DATA COLLECTION AND ANALYSIS

We assessed the studies found in the literature searches for possible inclusion and for their methodological quality. We contacted the authors of all included studies and of possibly randomized trials for supplemental information about the methods used and outcomes studied. We entered the data into RevMan and calculated odds ratios for the outcome measures of efficacy, breakthrough bleeding, spotting, withdrawal bleeding and discontinuation.

MAIN RESULTS

Of 23 trials included, 19 examined contraceptive effectiveness. The triphasic and monophasic preparations did not differ significantly. Several trials reported favorable bleeding patterns, that is less spotting, breakthrough bleeding or amenorrhea, in triphasic versus monophasic OC users. However, meta-analysis was generally not possible due to differences in measuring and reporting the cycle disturbance data as well as differences in progestogen type and hormone dosages. No significant differences were found in the numbers of women who discontinued due to medical reasons, cycle disturbances, intermenstrual bleeding or adverse events.

AUTHORS' CONCLUSIONS

The available evidence is insufficient to determine whether triphasic OCs differ from monophasic OCs in effectiveness, bleeding patterns or discontinuation rates. Therefore, we recommend monophasic pills as a first choice for women starting OC use. Large, high-quality RCTs that compare triphasic and monophasic OCs with identical progestogens are needed to determine whether triphasic pills differ from monophasic OCs. Future studies should follow the recommendations of Belsey or Mishell on recording menstrual bleeding patterns and the CONSORT reporting guidelines.

Cycle control and bleeding pattern of a 24/4 regimen of drospirenone 3 mg/ethinylestradiol 20 μg compared with a 21/7 regimen of desogestrel 150 μg/ethinylestradiol 20 μg: a pooled analysis

BACKGROUND AND OBJECTIVE

The degree of cycle control achieved with a hormonal contraceptive method is an important determinant of its acceptance and continuation. This study set out to compare the cycle control and bleeding profile of drospirenone (DRSP) 3 mg/ethinylestradiol (EE) 20 μg in a 24-active pill/4-inert pill (24/4) regimen (YAZ®) with those of desogestrel (DSG) 150 μg/EE 20 μg in a 21/7 regimen (Mercilon®), an established European combined oral contraceptive (COC).

METHODS

Bleeding data from women aged 17-36 years who received either DRSP 3 mg/EE 20 μg in a 24/4 regimen (n = 1285) or DSG 150 μg/EE 20 μg in a 21/7 regimen (n = 471) during four clinical studies were pooled and analysed over seven treatment cycles.

RESULTS

The maximum intensity of scheduled withdrawal bleeding was 'normal bleeding' for >50% of subjects in cycles 1-6 in both treatment groups. Moreover, the incidence of unscheduled intracyclic bleeding during cycles 2-7 was comparable between treatment types (10.2-14.9% in women treated with DRSP 3 mg/EE 20 μg 24/4 vs 8.6-13.8% in women treated with DSG 150 μg/EE 20 μg 21/7). Overall, similar bleeding patterns were observed with both treatments.

CONCLUSION

DRSP 3 mg/EE 20 μg 24/4 is associated with a bleeding profile and cycle control that is comparable to that of an established, low-dose COC formulation.

Pharmacological therapy for abnormal uterine bleeding

Pharmacological therapies for the treatment of abnormal uterine bleeding are effective and generally well tolerated. This review presents an evidence-based approach to medical therapy. Selection depends on the etiology and amount of bleeding, need for contraception or preservation of fertility, perimenopause status, and medication efficacy and adverse effects.Available nonhormonal agents include nonsteroidal anti-inflammatory agents, which reduce bleeding by 25% to 35% and improve dysmenorrhea through reduced prostaglandin levels; tranexamic acid, which inhibits plasminogen activator with a 40% to 60% reduction in menstrual blood loss; and intranasal desmopressin, which is an antifibrinolytic for women with an underlying bleeding disorder (eg, von Willebrand disease).Hormonal regimens cause the inhibition of endometrial growth. Cyclic progestogen therapy for 21 days results in a significant reduction in menstrual blood loss. Limited data suggest that oral contraceptives reduce menstrual blood loss by 40% to 50% with decreased breast tenderness and dysmenorrhea and a reduction in risk of uterine and ovarian cancer. The progestin-releasing intrauterine devices are effective up to 97% by 6 months and provide relief of dysmenorrhea and contraception. Long-acting progestogen injections produce amenorrhea and provide contraception but are associated with irregular spotting and reversible bone loss. Danazol leads to endometrial atrophy with a reduced menstrual loss; androgenic adverse effects may be lessened with lower doses or vaginal use. Gonadotrophin agonists lead to ovarian suppression and are used to shrink fibroids or the endometrium preoperatively but are limited by hypoestrogenic adverse events. Emergency use of parenteral conjugated estrogens has a 70% chance of stopping abnormal bleeding but an increased risk of thrombosis.

Types of progestogens in combined oral contraception: effectiveness and side-effects

BACKGROUND

The progestogen component of combined oral contraceptives (COC) has undergone changes since it was first recognised that it's chemical structure could influence the spectrum of minor adverse and beneficial effects. The major determinants of effectiveness are compliance and continuation which may be influenced by cycle control and common side effects. The rationale of this review is to provide a systematic comparison of COCs containing the progestogens currently in use worldwide.

OBJECTIVES

To compare currently available low-dose COCs containing ethinyl estradiol and different progestogens in terms of contraceptive effectiveness, cycle control, side effects and continuation rates.

SEARCH STRATEGY

A search of PubMed, LILACS, EMBASE, Popline, CINAHL and the Cochrane Central Register of Controlled Trials databases was conducted in September 2010 to update the 2004 review.

SELECTION CRITERIA

Randomised trials reporting clinical outcomes were considered for inclusion. We excluded studies comparing monophasic with multiphasic pills, crossover trials, trials in which the difference in total content of ethinyl estradiol between preparations exceeded 105 µg per cycle and those comparing continuous dosing regimens.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed methodological quality, applied inclusion criteria and extracted data.

MAIN RESULTS

Thirty trials with a total of 13,923 participants were included, generating 16 comparisons. Overall the quality of trials was low. Only four trials were double-blind. At least twenty-three trials were sponsored by pharmaceutical companies. There was less discontinuation with second-generation compared with first-generation monophasic progestogens (3 trials, 2,709 women, Relative Risk (RR) 0.76, 95% Confidence Interval (CI) 0.67-0.86); this remained significant when only double-blind trials were considered (812 women, RR 0.79, 95% CI 0.66-0.94).Women using monophasic COC's containing third-generation progestogens were less likely to discontinue than the second-generation group (3 trials, 1,815 women, RR 0.77, 95% CI 0.60-0.98) but this was not significant when only double-blind trials were considered (RR 0.79, 95% CI 0.50-1.26]. Women in the third-generation group experienced less intermenstrual bleeding than the second-generation group (one double-blind trial, 456 women, RR 0.71, 95% CI 0.55-0.91).Compared to desogestrel (DSG), women in the drospirenone (DRSP) group were more likely to complain of breast tenderness (5 trials, 4,258 women, RR 1.39, 95% CI 1.04-1.86) and nausea (6 trials, 4,701 women, RR 1.46, 95% CI 0.96-2.21].Pregnancy rates overall were comparable but the trials had insufficient power to find potentially important differences.

AUTHORS' CONCLUSIONS

Women using COCs containing second-generation progestogens may be less likely to discontinue than those using COCs containing first-generation progestogens. Based on one small double-blind trial, third-generation progestogens may be preferable to second-generation preparations with regard to bleeding patterns but further evidence is needed. Without blinding as to treatment group, comparisons between the various "generations" of progestogens used in COCs cannot be made. Until this widespread methodological flaw is overcome in better trials conducted according to CONSORT guidelines and internationally accepted definitions, no further conclusions can be drawn.

20 µg versus >20 µg estrogen combined oral contraceptives for contraception

BACKGROUND

Concern about estrogen-related adverse effects has led to progressive reductions in the estrogen dose in combination oral contraceptives (COCs). However, reducing the amount of estrogen to improve safety could result in decreased contraceptive effectiveness and unacceptable changes in bleeding patterns.

OBJECTIVES

To test the hypothesis that COCs containing ≤ 20 μg ethinyl estradiol (EE) perform similarly as those containing > 20 μg in terms of contraceptive effectiveness, bleeding patterns, discontinuation, and side effects.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE, POPLINE, ClinicalTrials.gov, and ICTRP, and examined references of eligible trials. Initially, we wrote to oral contraceptive manufacturers to identify trials.

SELECTION CRITERIA

English-language reports of randomized controlled trials were eligible that compare a COC containing ≤ 20 μg EE with a COC containing > 20 μg EE. We excluded studies where the interventions were designed to be administered for less than three consecutive cycles or to be used primarily as treatment for non-contraceptive conditions. Trials had to report on contraceptive effectiveness, bleeding patterns, trial discontinuation due to bleeding-related reasons or other side effects, or side effects to be included in the review.

DATA COLLECTION AND ANALYSIS

One author evaluated all titles and abstracts from literature searches to determine whether they met the inclusion criteria. Two authors independently extracted data from studies identified for inclusion. We wrote to the researchers when additional information was needed. Data were entered and analyzed with RevMan.

MAIN RESULTS

No differences were found in contraceptive effectiveness for the 13 COC pairs for which this outcome was reported. Compared to the higher-estrogen pills, several COCs containing 20 μg EE resulted in higher rates of early trial discontinuation (overall and due to adverse events such as irregular bleeding) as well as increased risk of bleeding disturbances (both amenorrhea or infrequent bleeding and irregular, prolonged, frequent bleeding, or breakthrough bleeding or spotting).

AUTHORS' CONCLUSIONS

While COCs containing 20 μg EE may be theoretically safer, this review did not focus on the rare events required to assess this hypothesis. Data from existing randomized controlled trials are inadequate to detect possible differences in contraceptive effectiveness. Low-dose estrogen COCs resulted in higher rates of bleeding pattern disruptions. However, most trials compared COCs containing different progestin types, and changes in bleeding patterns could be related to progestin type as well as estrogen dose. Higher follow-up rates are essential for meaningful interpretation of results.

50 years of "The Pill": celebrating a golden anniversary

The past 50 years have seen great advances in combined oral contraceptives (COCs) that have resulted in reduced risks of adverse events and improved cycle control. The most important changes in COCs over time include repeated lowering of the estrogen dose, development of new progestogens, and the reduction or elimination of the pill-free interval. Most recently, formulations that deliver estradiol in lieu of ethinylestradiol have been introduced. The advantages of COCs generally far outweigh the disadvantages. Current options in oral contraception include a wide spectrum of products that enable clinicians to choose the most appropriate formulation for individual women. This article summarises the advances in oral contraceptives over time and describes the most current clinical data regarding the use of COCs.