Oral contraceptives and risk of endometriosis: a systematic review and meta-analysis.
Summary of "Oral contraceptives and risk of endometriosis: a systematic review and meta-analysis."
BACKGROUND Combined oral contraceptives (OCs) inhibit ovulation, substantially reduce the volume of menstrual flow and may hypothetically interfere with implantation of refluxed endometrial cells. The aim of this review is to establish if OC use influences the risk of endometriosis. METHODS We performed a MEDLINE search to identify all studies published in the last four decades (January 1970 to January 2010) in the English language on the relationship between OC exposure and risk of endometriosis. Two authors abstracted data on standardized forms. RESULTS We identified 608 potentially relevant studies and 18 studies (6 cross-sectional, 7 case-control and 5 cohort) were selected. Pooling of the results derived from all the included reports independently from study design, yielded a common relative risk of 0.63 [95% confidence interval (CI), 0.47-0.85] for current OC users, 1.21 (95% CI, 0.94-1.56) for past users and 1.19 (95% CI, 0.89-1.60) for ever users. Methodological drawbacks, such as uncertain temporal relationship between exposure and outcome in cross-sectional studies and suboptimal selection of controls in case-control studies, limit the quality of the available evidence. CONCLUSIONS The risk of endometriosis appears reduced during OC use. However, it is not possible to exclude the possibility that the apparent protective effect of OC against endometriosis is the result of postponement of surgical evaluation due to temporary suppression of pain symptoms. Confounding by selection and indication biases may explain the trend towards an increase in risk of endometriosis observed after discontinuation, but further clarification is needed. To date, the hypothesis of recommending OCs for primary prevention of endometriosis does not seem sufficiently substantiated.
Clinica Ostetrica e Ginecologica I, Istituto 'Luigi Mangiagalli', Università Statale di Milano, Fondazione IRCCS 'Ca' Granda' - Ospedale Maggiore Policlinico, Via Commenda 12, Milan 20122, Italy.
This article was published in the following journal.
Name: Human reproduction update
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20833638
- DOI: http://dx.doi.org/10.1093/humupd/dmq042
Medical and Biotech [MESH] Definitions
Works consisting of studies using a quantitative method of combining the results of independent studies (usually drawn from the published literature) and synthesizing summaries and conclusions which may be used to evaluate therapeutic effectiveness, plan new studies, etc. It is often an overview of clinical trials. It is usually called a meta-analysis by the author or sponsoring body and should be differentiated from reviews of literature.
Contraceptives, Oral, Hormonal
Oral contraceptives which owe their effectiveness to hormonal preparations.
Contraceptives, Oral, Synthetic
Oral contraceptives which owe their effectiveness to synthetic preparations.
Drug Utilization Review
Formal programs for assessing drug prescription against some standard. Drug utilization review may consider clinical appropriateness, cost effectiveness, and, in some cases, outcomes. Review is usually retrospective, but some analysis may be done before drugs are dispensed (as in computer systems which advise physicians when prescriptions are entered). Drug utilization review is mandated for Medicaid programs beginning in 1993.
Contraceptives, Oral, Sequential
Drugs administered orally and sequentially for contraceptive purposes.
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