What is the most relevant standard of success in assisted reproduction?

Defining outcome in ART: a Gordian knot of safety, efficacy and quality

Jolande A. Land1,2 and Johannes L.H. Evers1

1 Department of Obstetrics and Gynaecology, Research Institute Growth and Development (GROW), Academisch ziekenhuis Maastricht, and Maastricht University, Maastricht, The Netherlands

2 To whom correspondence should be addressed at: Department of Obstetrics and Gynaecology, Academisch ziekenhuis Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands. e-mail: jlan{at}sgyn.azm.nl


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In the course of the present Debate series, several new outcome measures for assisted reproduction have been proposed to encourage the transfer of fewer embryos, in order to diminish the number of multiple pregnancies. The implementation of these recommendations, however, is hampered by the perception that safety and efficacy are communicating vessels: it is presumed that by decreasing the number of embryos transferred, pregnancy rates will decrease as well. Data from national and international registries, however, do not confirm the assumption of the communicating vessels: pregnancy rates tend to be low in countries in which many embryos are transferred, and the highest pregnancy rates occur where the number of embryos per transfer is low. Only top-level clinics (where treatment efficacy is guaranteed) are able to decrease the number of embryos transferred without compromising their pregnancy rate, and to vouch for safety in this way. Elective single embryo transfer (eSET) can never be mandatory in all patients, but the percentage of eSETs performed by a particular assisted reproduction treatment centre does reflect its quality: the ultimate outcome measure of efficacy ánd safety. Therefore, the eSET rate is the most relevant qualifier of performance in assisted reproduction.

Key words: ART quality/assisted reproduction/outcome measures/single embryo transfer/success rates


   
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For more than two decades now, the crude pregnancy rate has been the undisputed measure of treatment outcome in IVF. The ultimate goal was to achieve the highest pregnancy rates, which were considered to reflect excellent clinical performance, to provide prestige to the centre, and to be decisive in the competition for patients. Today, in many countries, pregnancy without taking maternal and neonatal risks and complications into consideration is no longer the ultimate objective. The most recently published, sixth edition of the Code of Practice of the British Human Fertilisation and Embryology Authority (HFEA, 2004Go) aims to reduce the risk of multiple births in women undergoing infertility treatment, while maximizing women’s chances of having a healthy baby. In this journal, a debate has been initiated about how to redefine assisted reproduction treatment (ART) outcome, taking safety as well as efficacy into account.

If we agree that the goal of assisted reproduction should be maximizing a woman’s chance of having a healthy baby, and if at the same time we aim at reducing the greatest single risk associated with assisted reproduction, i.e. multiple pregnancy, we could decide to adopt an outcome measure that rewards efficacy (many healthy singleton babies) and penalizes unsafety (multiple embryo transfer). This would be the corrected singleton live birth rate per cycle started, i.e. the singleton live birth rate per cycle started (SLBRPCS) minus the multiple live birth rate per cycle started (MLBRPCS). For Europe, in the year 2000, this figure (SLBRPCS – MLBRPCS) would vary between 3.3% for Ukraine, which reaches a delivery rate per cycle started of 15.3% at the expense of almost 40% multiples, and 12.1% for Finland, which reaches 19.7% deliveries/cycle with <20% multiples (ESHRE, 2004Go). The resulting parameter, SLBRPCS – MLBRPCS, would be difficult to envisage however.

Several other proposals for new end-points have been made to encourage the transfer of fewer embryos, in order to diminish the number of multiple pregnancies. The implementation of these recommendations, however, is hampered by the perception that safety and efficacy are communicating vessels: by decreasing the number of embryos transferred, pregnancy rates will be reduced as well. However, it has been shown that triplets can be avoided by replacing two embryos (Staessen et al., 1995Go; Templeton and Morris, 1998Go), and that twins can be avoided by replacing one embryo (Martikainen et al., 2001Go; Gerris et al., 2002Go), without significantly decreasing the overall pregnancy rate. These findings confirm that in selected groups of patients, increasing the number of embryos transferred will not improve the overall pregnancy rate any further, but only result in a higher multiple pregnancy rate (Martin and Welch, 1998Go). The characteristics of patients and embryos with high implantation potential are still poorly defined. However, recent observations from the University Hospital in Helsinki (Tiitinen et al., 2003Go), where elective single embryo transfer (eSET) is performed in 56% of all cycles and pregnancy rates remain over 30%, cast doubt upon very strict selection criteria. The clinics performing eSET in a substantial proportion of their patients have been shown to be capable of combining safety with efficacious treatment, which reflects a high standard of clinical quality.

In spite of the convincing observations on pregnancy rates after elective single and double embryo transfers, from the annual reports on the year 2000 of European (ESHRE, 2004Go), American (MMWR, 2003Go) and Australian registries (AIHW, 2003Go), it can be concluded that in a substantial number of patients, three or more embryos are still transferred. However, the data from these registries do not confirm the assumption of the communicating vessels: pregnancy rates tend to be low in countries in which many embryos are transferred, and the highest pregnancy rates are found where the number of embryos per transfer is low (Figure 1). This inverse relationship between efficacy and safety cannot be explained by differences in patient populations, which are very similar in developed countries, but rather is due to differences in laboratory expertise (in culturing and selecting embryos) and clinical skills (in ovarian stimulation leading to an adequate number of embryos and optimal endometrial receptivity). Only top-level clinics (where treatment efficacy is guaranteed) are able to decrease the number of embryos transferred without compromising their pregnancy rate, and to vouch for safety in this way.



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Figure 1. Percentage of deliveries per ovum pick-up (defined as efficacy) related to the number of embryos transferred per ovum pick-up (inversely related to the risk for multiple pregnancies, and reflecting safety), given for European countries, and summarized for Europe, the USA, and Australia and New Zealand. The four quadrants represent different combinations of efficacy and safety. Only in the upper left, shaded, quadrant is high efficacy combined with high safety, indicating high quality. Data are derived from the annual reports for the year 2000 of European (ESHRE, 2004), American (MMWR, 2003) and Australian registries (AIHW, 2003).

 
We conclude that eSET can never be mandatory in all patients. The percentage of eSET performed by a particular ART centre, however, reflects its quality: the ultimate outcome of efficacy and safety. Therefore, the eSET rate is the most relevant qualifier of performance in assisted reproduction.


    References
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AIHW. (2003) Assisted conception Australia and New Zealand 2000 and 2001. Australian Institute of Health and Welfare, National Perinatal Statistics Unit, Sydney, accessible at www.npsu.unsw.edu.au/ac7.pdf.

ESHRE. (2004) The European IVF-monitoring programme (EIM), for the European Society of Human Reproduction and Embryology (ESHRE). Assisted reproductive technology in Europe, 2000. Results generated from European registers by ESHRE. Hum Reprod 19,1–15.[CrossRef][Medline]

Gerris J, De Neubourg D, Mangelschots K, Van Royen E, Vercruyssen M, Barudy-Vasquez J, Valkenburg M and Ryckaert G (2002) Elective single day 3 embryo transfer halves the twinning rate without decrease in the ongoing pregnancy rate of an IVF/ICSI programme. Hum Reprod 17,2626–2631.[Abstract/Free Full Text]

HFEA. (2004) Human Fertilisation and Embryology Authority, Code of Practice, accessible at www.hfea.gov.uk.

Martikainen H, Tiitinen A, Tomás C, Tapanainen J, Orava M, Tuomivaara L, Vilska S, Hydén-Granskog C, Hovatta O and the Finnish ET Study Group (2001) One versus two embryo transfer after IVF and ICSI: a randomised study. Hum Reprod 16,1900–1903.[Abstract/Free Full Text]

Martin PM and Welch HG (1998) Probabilities for singleton and multiple pregnancies after in vitro fertilization. Fertil Steril 70,478–481.[CrossRef][Medline]

MMWR. (2003) Assisted Reproductive Technology Surveillance United States, 2000. Surveilance Summaries 2003, 52 (SS09), 1–16 at www.cdc.gov/mmwr/preview/mmwrhtml/ss5209a1.htm.

Staessen C, Nagy ZP, Liu J, Janssenswillen C, Camus M, Devroey P and Van Steirteghem AC (1995) One year’s experience with elective transfer of two good quality embryos in the human in-vitro fertilization and intracytoplasmatic sperm injection programmes. Hum Reprod 10,3305–3312.[Abstract]

Templeton A and Morris JK (1998) Reducing the risk of multiple births by transfer of two embryos after in vitro fertilization. N Engl J Med 339,573–577.[Abstract/Free Full Text]

Tiitinen A, Unkila-Kallio L, Halttunen M and Hydén-Granskog C (2003) Impact of elective single embryo transfer on the twin pregnancy rate. Hum Reprod 18,1449–1453.[Abstract/Free Full Text]