Benefits and risks of hormonal contraception for women.

SCIENTIFIC BACKGROUND

A large proportion of women of reproductive age in Germany use various methods of pregnancy prevention (contraception), among them various hormone-based methods. Hormonal contraceptives may be divided into combined estrogen-progestogen contraceptives (pills, skin patches, vaginal rings), progestogen-only contraceptives (pills, injections, implants, hormone spirals) and emergency contraceptives.

RESEARCH QUESTIONS

The evaluation addressed the question of benefits and risks of hormonal contraceptives, their economic effects as well as their ethical-social and legal implications.

METHODS

A systematic literature search was conducted in April 2006 starting from 2000. The evaluation is primarily based on systematic reviews.

RESULTS

In perfect use, all hormonal contraceptives excluding emergency contraceptives proved to be the most effective reversible contraceptive methods (rate of unintended pregnancies 0.05% to 0.3%). However, the typical use of oral contraceptives, injections, skin patches, and vaginal rings, which also considers possible application errors, showed a lower contraceptive efficacy (rate of unintended pregnancies 3% to 8%). It was lower than that of copper spirals. The risk of venous thromboembolism increased three to six times in users of hormonal contraceptives, the risks of stroke and myocardial infarction two to three times. The risk declined after discontinuation of use. The effects were estrogen-dose and progestogen-type dependent. The use of hormonal contraceptives showed a relative risk of ovarian and endometrial carcinomas of approximately 0.5 or 0.7, of breast and cervical cancer of approximately 1.2 or 1.6. The effect remained several years after discontinuation of use. The results concerning hepatocellular carcinoma suggested a carcinogenic effect. In women with acne, an improvement due to use of hormonal contraceptives was proven. Cervical chlamydial infections were more frequent in users of hormonal contraception. Headache appeared mostly only at the beginning of the use of combined oral contraceptives. Progestogen-only contraceptives worsened the results of the glucose tolerance test. A review of low evidence reported further risks of hormonal contraceptives (concerning menstrual problems, ovarian cysts, bone density, thyroid diseases and rheumatoid arthritis) as well as further benefits (concerning blood pressure and Crohn's disease). Hormonal spirals were shown to be more effective than spirals which do not release hormones. In emergency contraception, Levonorgestrel was more effective than the Yuzpe method. Most other proven differences between hormonal contraceptives were related to menstrual problems. After spirals with or without hormone release, the other hormonal contraceptives were shown in typical use to be the second most cost-effective reversible methods of contraception.

DISCUSSION

The addressed questions could be answered only on relatively low evidence level, partly only for applications with estrogen doses which are not used in Germany any more. The transferability of the results of the analysed primary health-economics studies on the current situation in Germany is limited (clinical assumptions from out-dated information sources of low evidence levels, cost assumptions from the American health system).

CONCLUSIONS

In perfect use, hormonal contraceptives have to be classified as the most effective reversible contraceptive methods. For the individual decision concerning the use of hormonal contraception, benefits should be related to the additional risks. Alternative methods such as spirals should be prioritised if perfect use seems to be impossible. In this case, spirals are also preferable from health-economics perspective. No ethical-social or legal conclusions can be derived from the available data.