The effectiveness of different down-regulating protocols on in vitro fertilization-embryo transfer in endometriosis: a meta-analysis

Background To investigate the effectiveness of the GnRH-a ultra-long protocol, GnRH-a long protocol, and GnRH-a short protocol used in in vitro fertilization-embryo transfer (IVF-ET) in infertile women with endometriosis. Methods We searched PubMed, Embase, Web of Science, Cochrane Library, Elsevier Science Direct, OA Library, Google Scholar, China National Knowledge Infrastructure (CNKI), Wanfang Data Knowledge Service Platform, China Science and Technology Journal database, and the China Biology Medicine disc for randomized controlled trials (RCTs) and observational studies (non-RCTs) to evaluate the efficacy of the GnRH-a ultra-long protocol, GnRH-a long protocol, and GnRH-a short protocol in IVF-ET in infertile patients with endometriosis. Results A total of 21 studies in compliance with the standard literature were included, and RCT and non-RCT studies were analyzed separately. This meta-analysis showed that the GnRH-a ultra-long protocol could improve the clinical pregnancy rate of infertile patients in RCT studies, especially in patients with stages III-IV endometriosis (RR = 2.04, 95% CI: 1.37 similar to 3.04, P < 0.05). However, subgroup analysis found the different down-regulation protocols provided no significant difference in improving clinical outcomes in patients with endometriosis in the non-RCT studies. Conclusion This study suggests that the GnRH-a ultra-long protocol can improve the clinical pregnancy rate of the patients with stages III-IV endometriosis in RCT studies. Although it is generally believed that the results of RCT are more reliable, the conclusions of the non-RCT studies cannot be easily neglect, which let us draw conclusions more cautious.