The updated Cochrane review 2014 on GnRH agonist trigger: repeating the same errors

Cochrane reviews are powerful tools, internationally recognized as the highest standard in evidence-based health care. A Cochrane analysis makes use of precise, reproducible criteria in the selection of studies for review. In the context of a previous Cochrane review (2010) on the subject of gonadotrophin-releasing hormone agonist (GnRHa) trigger, we questioned whether a review should be conducted during the research phase when new concepts are being developed. Recently, an updated Cochrane review was published, reaching the same general conclusion as the first one, i.e., GnRHa triggers lower the chance of pregnancy in fresh autologous IVF and intracytoplasmic injection treatment cycles. We argue that the new review repeats previous errors by compiling data from studies that were not comparable as different luteal phase protocols were used. From the clinical point of view, the luteal support used is the variable which affects the pregnancy rate and not the use of the GnRHa trigger for final oocyte maturation. Therefore, a meaningful comparison between GnRHa and HCG trigger must be confined to outcome measures that are not affected by the luteal support used. We conclude that the updated review falls short of addressing meaningful clinical and fundamental questions in the context of GnRHa trigger.