Human Reproduction, Vol. 15, No. 11, 2447-2448,
November 2000
© 2000 European Society of Human Reproduction and Embryology
Letters to the editor |
Evidence may change with more trials: concepts to be kept in mind
Cairo University, Egypt Member of the MDSG, Cochrane Collaboration
Dear Sir,
I read with great interest the article by the ESHRE Capri Workshop Group (2000) on the `optimal use of infertility diagnostic tests and treatments' but I became a little bit confused with regard to the item concerned with treatments of endometriosis. Reading the article, it was obvious that the Capri workshop group participants were presenting the best available evidence on different topics of the article. However, this was not the case when discussing the role of surgery in treatment of pelvic endometriosis in subfertile females. The article mentioned a previous trial (Marcoux et al., 1997
) and I agree that it is the largest randomized controlled trial (RCT) on endometriosis to date, but there was no mention of another RCT addressing the same issue (Gruppo Italiano per lo Studio Dell'Endometriosi, 1999). On pooling the results of the two studies, the odds ratio was 1.5 (95% confidence interval 0.9–2.4; Evers, 1999). Thus, it would be better to say `there is insufficient evidence to support the positive effect of surgical treatment of endometriosis rAFS stages I–II in subfertile females'.
I noticed that the Capri workshop meeting was in August 1998 and the article was published in March 2000 but I also noticed one of the references (Gruppo Italiano per lo Studio Dell'Endometriosi, 1999) was published in 1999 which means that the article was updated since the meeting. This trial has changed the evidence and we should all be aware of that.
References
ESHRE Capri Workshop Group (2000) Optimal use of infertility diagnostic tests and treatments. Hum. Reprod., 15, 723–732.
Evers, J.H. (1999) The role of surgery in the treatment of pelvic endometriosis in subfertile patients. Middle East Fertil. Soc. J., 4, 19–27.
Gruppo Italiano per lo Studio Dell'Endometriosi (1999) Ablation of lesions or no treatment in inimal-mild endometriosis in infertile women: a randomized trial. Hum. Reprod., 14, 1332–1334.
Marcoux, S., Maheux, R. and Berube, S. (1997) The Canadian Collaborative Group on Endometriosis. Laparoscopic surgery in infertile women with minimal or mild endometriosis. N. Engl J. Med., 337, 217–222.
Clinica Ostetrica e Ginecologica I Facolta di Medicina e Chirurgia Universita Degli Studi di Milano Via Commenda, 12-20122 Milano Italy
Dear Sir,
Dr Al-Inany's letter gives us the opportunity of discussing once again the debated issue of the effect of ablation of limited endometriotic lesions in infertile women. Based on the results of an Italian multicentre trial (Gruppo Italiano per lo Studio dell'Endometriosi, 1999), which had not been published when the ESHRE Capri document was finalized (ESHRE Capri Workshop Group, 2000), Dr Al-Inany maintains that the evidence favouring endometriosis ablation has changed. In fact he quotes the common odds ratio (OR) of 1.5 (Evers, 1999) calculated for the two published trials on the topic (Marcoux et al., 1997; Gruppo Italiano per lo Studio dell'Endometriosi, 1999) and, based on the lower confidence limit which is just below unity [95% confidence interval (CI) 0.9–2.4], suggests that there is now insufficient evidence to support the notion that surgical treatment of minimal to mild endometriosis in subfertile women is beneficial. A biometric and/or a common-sense approach may be adopted to address this issue.
In the article cited by Al-Inany (Evers, 1999) the common OR was computed pooling two different outcomes, i.e. only pregnancies at >20 weeks gestation in the Canadian trial and any conception in the Italian study. However, in our opinion the same outcome should be chosen before pooling the results, either all conceptions (63/172 in the ablation group versus 37/169 in the no-surgery group for the Canadian trial and, respectively, 12/54 versus 13/47 for the Italian study) or only late pregnancies (50/172 versus 29/169 and 10/54 versus 10/47 respectively). In the former case the common OR is 1.65 (95% CI, 1.06 to 2.58) and in the latter it is 1.64 (95% CI, 1.02–2.67), with neither confidence intervals including unity. Consequently, it does not seem that failure of manuscript updating, as suggested by Dr Al-Inany, has changed much from what was reported in the ESHRE Capri document. Moreover, the Italian trial did not have the power to detect the between-group difference in pregnancy rate observed in the Canadian study, and the 95% CIs of the ORs of the two studies largely overlap.
As clinicians, obviously we would not consider radically changing our way of counselling infertile patients with limited endometriosis based on such subtle statistical variations. Instead, we may wish to express the results more practically in terms of number of women to undergo surgery to achieve an additional pregnancy. In this case, even taking into account only the results of the Canadian trial, the benefit of laparoscopic ablation appears less encouraging. In fact, eight women with minimal to mild endometriosis need to undergo laparoscopic ablation to achieve an additional late pregnancy. However, considering that we cannot identify women with endometriosis preoperatively, and that the proportion of subjects with endometriosis in the Canadian series of patients undergoing laparoscopy for unexplained infertility was a little <50%, the number needed to be treated doubles at least. Put in this perspective, laparoscopic surgery remains biometrically effective even after publication of the Italian study but, in the absence of pain symptoms, appears clinically little appealing. In our opinion this has been adequately expressed in the ESHRE Capri document, the abstract of which clearly states that randomized controlled trials `demonstrated the modest efficacy of endometriosis ablation in increasing the pregnancy rate in infertile women'.
Notes
1 To whom correspondence should be addressed On behalf of the ESHRE Capri Workshop Group 
References
Evers, J.L.H. (1999) The role of surgery in the treatment of pelvic endometriosis in subfertile patients. Middle East Fertil. Soc. J., 4, 19–21.
Gruppo Italiano per lo Studio dell'Endometriosi (1999) Ablation of lesions or no treatment in minimal-mild endometriosis in infertile women: a randomized trial. Hum. Reprod., 14, 1332–1334.
Marcoux, S., Maheux, R., Berube, S. et al. (1997) Laparoscopic surgery in infertile women with minimal or mild endometriosis. N. Engl. J. Med., 337, 217–222.
The ESHRE Capri Workshop Group (2000) Optimal use of infertility diagnostic tests and treatments. Hum. Reprod., 15, 723–732.
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