Hum. Reprod. Advance Access originally published online on July 18, 2007
Human Reproduction 2007 22(10):2796; doi:10.1093/humrep/dem234
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Letters to the Editor |
Reply: Effect of GnRH antagonists in FSH mildly stimulated intrauterine insemination cycles: a multicentre randomized trial
II Department of Obstetrics and Gynecology, University of Milano, Via Commenda 12, 20122 Milano, Italy
1 Correspondence address. Tel: +39-0250320256; Fax: +39-0250320255; E-mail: piergiorgio.crosignani{at}unimi.it
We would like first to thank Drs. Niraj Mahajan, Kshitija Mahajan and Rajani Soni for their interest in our paper (Crosignani et al., 2007
). In their brief comment, these authors have emphasized several important albeit still unclear aspects of controlled ovarian hyperstimulation (COH) and intrauterine insemination (IUI). Does double insemination provide any benefit? What is the most suitable protocol of COH? Are there factors that are able to reliably predict multiple pregnancies? Where there is a high risk for multiple births, is there any effective alternative to cancellation? Answers to these questions represent a challenging task, which at present is far from being resolved.
In this regard, we would like to underline the urgent need for large randomized clinical trials (RCT) for COH and IUI. Unfortunately, results from this type of study design are extremely scant. A major problem in designing RCTs in this field is related to the large sample size needed. Reasons for this necessity are essentially two-fold. First, due to statistical concerns, patients should be enrolled only for their first treatment cycle and the crossover study design (which requires a lower number of subjects) should be avoided (Daya, 2003). Second, given the relatively low rate of success of the procedure (10–12% per cycle), the number of couples to be recruited in randomized studies is remarkably large. Stating as clinically relevant an absolute increase of the pregnancy rate of 5% and setting the type I and type II errors at 0.05 and 0.20, respectively, the number of couples needed to be enrolled is >1000 for each study group (Mittendorf et al., 1995). A single center has undoubtly many difficulties in enrolling a sufficient number of cases in an acceptable period of time. As a consequence, only large multicenter RCTs may consent to draw reliable conclusions. The study we have presented is the result of a spontaneous and unfunded collaboration (Crosignani et al., 2007). It has been an enriching experience and we hope it might be followed as an example for those who are interested in clarifying the still unclear aspects of COH and IUI.
References
Crosignani PG, Somigliana E, Intrauterine Insemination Study Group. Effect of GnRH antagonists in FSH mildly stimulated intrauterine insemination cycles: a multicentre randomized trial. Hum Reprod (2007) 22:500–505.
Daya S. Pitfalls in the design and analysis of efficacy trials in subfertility. Hum Reprod (2003) 18:1005–1009.
Mittendorf R, Arun V, Sapugay AM. The problem of the type II statistical error. Obstet Gynecol (1995) 86:857–859.[CrossRef][Web of Science][Medline]
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