Comparisons of GnRH antagonist versus GnRH agonist protocol in poor ovarian responders undergoing IVF

BACKGROUND: In view of the discrepancies about the GnRH antagonist (GnRH-ant) ovarian stimulation protocols having some potential advantages compared with the GnRH agonist (GnRH-a) protocols in poor ovarian responders IVF/ICSI, a meta-analysis of the published data was performed to compare the efficacy of GnRH-ant versus GnRH-a protocols for ovarian stimulation in IVF poor response patients. METHODS: We searched for all published articles indexed in MEDLINE (1950-2010), EMBASE (1974-2010) and China National Knowledge Infrastructure (CNKI, 1994-2010). Any randomized controlled study that compared the GnRH-ant with GnRH-a in ovarian stimulation protocols for poor responders undergoing IVF/ICSI was included, and data were extracted independently by two reviewers. The searches yielded 64 articles, from which 14 studies met the inclusion criteria. We performed this meta-analysis involving 566 IVF patients in a GnRH-ant protocol group and 561 patients in a GnRH-a protocol group with Review Manager 4.2 software. Odds ratio (OR) and weighted mean difference (WMD) with 95% confidence intervals (CIs) were used to evaluate dichotomous and continuous data, respectively. RESULTS: Fourteen eligible studies were included in this meta-analysis. GnRH-ant protocols resulted in a statistically significantly lower duration of stimulation compared with GnRH-a protocols (P = 0.04; WMD: -1.88, 95% CI: -3.64, -0.12), but there was no significant difference in the number of oocytes retrieved (P = 0.51; WMD: -0.17, 95% CI -0.69, 0.34) or the number of mature oocytes retrieved (P = 0.99; WMD: -0.01, 95% CI: -1.14, 1.12). Moreover, no significant difference was found in the cycle cancellation rate (CCR, P = 0.67; OR: 1.01, 95% CI: 0.71-1.42) or clinical pregnancy rate (CPR, P = 0.16; OR: 1.23, 95% CI: 0.92, 1.66). CONCLUSIONS: Clear advantage was gained in duration of stimulation with GnRH-ant in poor ovarian responders undergoing IVF, although there was no statistical difference in the number of oocytes retrieved, the number of mature oocytes retrieved, the CCR and CPR between GnRH-ant and GnRH-a protocols. These results may be helpful to our clinical practice. However, further controlled randomized prospective studies with larger sample sizes are needed.