Modern combined oral contraceptives for treatment of pain associated with endometriosis

Endometriosis is a common women's healthcare condition which is defined as the growth of endometrium (lining of the uterus) at sites outside the uterus, such as the ovaries. Endometriosis is commonly found in women with painful periods, pain with sexual intercourse, pelvic pain and infertility. Hormonal treatments, including the oral contraceptive pill (OCP) and gonadotrophin releasing hormone (GnRH) analogues are used to relieve the pain symptoms associated with endometriosis. There is some evidence to suggest that such treatments may also treat the actual deposits of endometriosis. However, many of the hormonal treatments have side effects which limit their acceptability and duration of use. Surgery may also be used to remove the deposits.

This review searched for studies which compared an OCP with other treatments. One small study (57 women) was found which compared an OCP to goserelin (a GnRH analogue) in two separate treatment groups. The study showed that the two treatments relieved endometriosis-associated pain equally well. The goserelin treatment stopped women from having periods. Clearly, therefore, these women did not report having pain with their periods during treatment. Goserelin can also only be safely taken for six months.
More women in the goserelin group had side effects of hot flushes, insomnia and vaginal dryness, whereas more women in the OCP group suffered headaches and weight gain. After six months follow up there were no differences between the groups. The methodology of the study was not rated highly by the review authors.

Authors' conclusions: 

The limited data we found available suggests that this is no evidence of a difference in outcomes between the oral contraceptive pill (OCP) studied and GnRH analogue was as effective as a GnRH analogue in treating for endometriosis-associated painful symptoms of endometriosis. However, the lack of studies with larger sample sizes, or focusing on other comparable treatments is concerning and further research is needed to fully evaluate fully the role of OCPs oral contraceptive pills in managing symptoms associated with endometriosis.

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Background: 

Endometriosis is a common gynaecological condition which affects many women of reproductive age worldwide and is a major cause of pain and infertility. The modern oral contraceptive pill is widely used to treat pain occurring as a result of endometriosis, although the evidence for its efficacy is limited.

Objectives: 

To assess the effects of the oral contraceptive pill (OCP) in comparison to other treatments for painful symptoms of endometriosis in women of reproductive age.

Search strategy: 

We searched the Menstrual Disorders and Subfertility Group Specialised Register of controlled trials; Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2006); MEDLINE (January 1966 to September 2006); EMBASE (1980 to September 2006); National Research Register; and reference lists of articles.

Selection criteria: 

All truly randomised controlled trials of the use of oral contraceptive pills in the treatment of women of reproductive age with symptoms ascribed to the diagnosis of endometriosis and made visually at surgical procedure were included.

Data collection and analysis: 

Study quality assessment and data extraction were carried out independently by two review authors. One of the assessors was an expert in the content matter. We contacted study authors for additional information.

Main results: 

Only one study met the inclusion criteria, in which a total of 57 women were allocated to two groups to compare an OCP to a GnRH analogue. Methods of randomisation and allocation concealment were unclear and the study was acknowledged by its authors to be underpowered. Women in the GnRH analogue group became amenorrhoeic during the treatment period of six months, whilst women in the OCP group reported a decrease in dysmenorrhoea. No evidence of a significant difference between the two groups was observed in terms of dysmenorrhoea at six months follow up after stopping treatment (OR 0.48; 95% CI 0.08 to 2.90). Some evidence for a decrease in dyspareunia was found at the end of treatment in women in the GnRH analogue group, although no evidence of a significant difference in dyspareunia was observed at the end of the six months follow up (OR 4.87; 95% CI 0.96 to 24.65).

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