Long-term GnRH agonist therapy before in vitro fertilisation (IVF) for improving fertility outcomes in women with endometriosis.

BACKGROUND Endometriosis is known to have an impact on fertility and it is common for women affected by endometriosis to require fertility treatments, including in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI), to improve the chance of pregnancy. It has been postulated that long-term gonadotrophin-releasing hormone (GnRH) agonist therapy prior to IVF or ICSI can improve pregnancy outcomes. This systematic review supersedes the previous Cochrane Review on this topic (Sallam 2006). OBJECTIVES To determine the effectiveness and safety of long-term gonadotrophin-releasing hormone (GnRH) agonist therapy (minimum 3 months) versus no pretreatment or other pretreatment modalities, such as long-term continuous combined oral contraception (COC) or surgical therapy of endometrioma, before standard in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) in women with endometriosis. SEARCH METHODS We searched the following electronic databases from their inception to 8 January 2019: Cochrane Gynaecology and Fertility Specialised Register of Controlled Trials, CENTRAL via the Cochrane CENTRAL Register of Studies ONLINE (CRSO), MEDLINE, Embase, PsycINFO, Cumulative Index to Nursing and Allied Health Literature (CINAHL). We searched trial registries to identify unpublished and ongoing trials. We also searched DARE (Database of Abstracts of Reviews of Effects), Web of Knowledge, OpenGrey, Latin American and Caribbean Health Science Information Database (LILACS), PubMed, Google and reference lists from relevant papers for any other relevant trials. SELECTION CRITERIA Randomised controlled trials (RCTs) involving women with surgically diagnosed endometriosis that compared use of any type of GnRH agonist for at least three months before an IVF/ICSI protocol to no pretreatment or other pretreatment modalities, specifically use of long-term continuous COC (minimum of 6 weeks) or surgical excision of endometrioma within six months prior to standard IVF/ICSI. The primary outcomes were live birth rate and complication rate per woman randomised. DATA COLLECTION AND ANALYSIS Two independent review authors assessed studies against the inclusion criteria, extracted data and assessed risk of bias. A third review author was consulted, if required. We contacted the study authors, as required. We analysed dichotomous outcomes using Mantel-Haenszel risk ratios (RRs), 95% confidence intervals (CIs) and a fixed-effect model. For small numbers of events, we used a Peto odds ratio (OR) with 95% CI instead. We analysed continuous outcomes using the mean difference (MD) between groups and presented with 95% CIs. We studied heterogeneity of the studies via the I2 statistic. We assessed the quality of evidence using GRADE criteria. MAIN RESULTS We included eight parallel-design RCTs, involving a total of 640 participants. We did not assess any of the studies as being at low risk of bias across all domains, with the main limitation being lack of blinding. Using GRADE methodology, the quality of the evidence ranged from very low to low quality. Long-term GnRH agonist therapy versus no pretreatment We are uncertain whether long-term GnRH agonist therapy affects the live birth rate (RR 0.48, 95% CI 0.26 to 0.87; 1 RCT, n = 147; I2 not calculable; very low-quality evidence) or the overall complication rate (Peto OR 1.23, 95% CI 0.37; to 4.14; 3 RCTs, n = 318; I2 = 73%; very low-quality evidence) compared to standard IVF/ICSI. Further, we are uncertain whether this intervention affects the clinical pregnancy rate (RR 1.13, 95% CI 0.91 to 1.41; 6 RCTs, n = 552, I2 = 66%; very low-quality evidence), multiple pregnancy rate (Peto OR 0.14, 95% CI 0.03 to 0.56; 2 RCTs, n = 208, I2 = 0%; very low-quality evidence), miscarriage rate (Peto OR 0.45, 95% CI 0.10 to 2.00; 2 RCTs, n = 208; I2 = 0%; very low-quality evidence), mean number of oocytes (MD 0.72, 95% CI 0.06 to 1.38; 4 RCTs, n = 385; I2 = 81%; very low-quality evidence) or mean number of embryos (MD -0.76, 95% CI -1.33 to -0.19; 2 RCTs, n = 267; I2 = 0%; very low-quality evidence). Long-term GnRH agonist therapy versus long-term continuous COC No studies reported on this comparison. Long-term GnRH agonist therapy versus surgical therapy of endometrioma No studies reported on this comparison. AUTHORS' CONCLUSIONS This review raises important questions regarding the merit of long-term GnRH agonist therapy compared to no pretreatment prior to standard IVF/ICSI in women with endometriosis. Contrary to previous findings, we are uncertain as to whether long-term GnRH agonist therapy impacts on the live birth rate or indeed the complication rate compared to standard IVF/ICSI. Further, we are uncertain whether this intervention impacts on the clinical pregnancy rate, multiple pregnancy rate, miscarriage rate, mean number of oocytes and mean number of embryos. In light of the paucity and very low quality of existing data, particularly for the primary outcomes examined, further high-quality trials are required to definitively determine the impact of long-term GnRH agonist therapy on IVF/ICSI outcomes, not only compared to no pretreatment, but also compared to other proposed alternatives to endometriosis management.