Center for Reproductive Medicine and Infertility, Cornell University Medical College, 505 East 70th Street, HT-334, New York, NY 10021, USA E-mail: glschatt{at}mail.med.cornell.edu
Dear Sir,
I would like to thank the authors (Busacca et al., 2001) for their contribution of a well designed, randomized study evaluating the effects of post-operative GnRH analogue use after conservative surgery in patients with symptomatic endometriosis. I am unsure, however, if this study was properly designed to answer their hypothesis. Patients desiring pregnancy who are infertile secondary to the anatomic distortion caused by severe endometriosis might be a distinct group from those undergoing laparoscopy primarily because of significant pelvic pain. Approximately one-third of patients in each group were attempting conception, thus limiting the power of the study, especially if patients conceived early in the course of the follow-up.
Secondly, baseline pain scores using a linear scale were reported to be obtained prior to surgical intervention as well as at each subsequent 6 month visit. What were the pain scores at baseline? Were the groups similar at baseline? Were there any differences in pain scores in individual patients before and after therapy? This qualitative difference in pre- and post-therapy score for each patient might be a better predictor of success than the percentage of patients with moderate to severe pain after some period of time.
While it is stated that other causes of pelvic pain were an exclusion criteria for the study, what did they look for and what methods were used to `rule these out'? Additionally, the procedures and techniques used to ablate the disease were performed according to technique of Cook and Rock (Cook and Rock, 1991); however, this paper describes multiple modalities including resection, laser, endocoagulation etc. Which technique was used primarily, if any?
The use of GnRH analogue for 3 months has been described by Hornstein to be as effective as 6 months for pelvic pain and dyspareunia, but not as good for pelvic tenderness 12 months after the cessation of therapy (Hornstein et al., 1995). Starting GnRH analogue in the early follicular phase of the menstrual cycle usually leads to an immediate `flare' of gonadotrophins and rise in serum estradiol levels which can last for 23 weeks until suppression occurs. Effective therapy is shortened by this period of time, which is one of the reasons I initiate GnRH analogue in the mid-luteal phase or after 2 weeks of oral contraceptives started on day 1 or 2 of menses overlapping with the GnRH analogue by 1 week.
Unfortunately, it is all too often perceived that only patients with `advanced' stages or `severe' disease suffer pain. The overwhelming majority of patients who undergo laparoscopy for chronic pelvic pain presumably secondary to visualized endometriosis actually have revised American Fertility Society classifications of stage I or II disease (Fedele et al., 1990; American Society for Reproductive Medicine, 1997
). It has been previously demonstrated in a randomized, controlled trial that it is patients with stage I or II disease, not those with `severe' endometriosis who have the highest recurrence rates post-operatively (Sutton et al., 1994
). Limiting the study to patients with stage III and IV disease limits the significance of the findings.
I agree with the authors that more studies need to be done utilizing appropriate patient populations and study design to answer many of the remaining questions on how to effectively treat patients suffering with chronic pelvic pain presumably due to endometriosis.
References
American Society for Reproductive Medicine (1997) Revised American Society for Reproductive Medicine classification of endometriosis. Fertil. Steril., 67, 817821.[ISI][Medline]
Busacca, M., Somigliana, E., Bianchi, S. et al. (2001) Post-operative GnRH analogue treatment after conservative surgery for symptomatic endometriosis stage IIIIV: a randomized controlled trial. Hum. Reprod., 16, 23992402.
Cook, A.S. and Rock, J.A. (1991) The role of laparoscopy in the treatment of endometriosis. Fertil. Steril., 55, 663680.[ISI][Medline]
Fedele, C., Parazinni, F., Bianchi, S. et al (1990) Stage and localization of pelvic endometriosis and pain. Fertil. Steril., 53, 155158.[ISI][Medline]
Hornstein, M.D., Yuzpe, A.A., Burry, K.A. et al. (1995) Prospective randomized double-blind trial of 3 versus 6 months of naferelin therapy for endometriosis associated pelvic pain. Fertil. Steril., 63, 959962.
Sutton, C.J., Ewen, S.P., Whitelaw, N. and Haines, P. (1994) Prospective, randomized, double blind, controlled trial of laser laparoscopy in the treatment of pelvic pain associated with minimal, mild and moderate endometriosis. Fertil. Steril., 62, 696700.[ISI][Medline]
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