Objective To assess the safety and efficacy of long-term use of long-acting GnRH agonist in women with chronic cyclical pelvic pain using immediate versus delayed add-back hormonal replacement therapy (HRT).
Design A prospective randomised trial.
Setting Reproductive and Developmental Medicine, Academic Unit, University Teaching Hospital and NHS Hospitals.
Population Thirty-eight premenopausal women with chronic cyclical pelvic pain were recruited.
Methods Women were given Zoladex 10.8 mg over 18 months and randomised to receive HRT (tibolone 2.5 mg) either immediately or after 6 months. Follow up was 12-month post-treatment.
Main outcome measures Bone mineral density at 6 months, the end of treatment (18 months), and 12 months later, pain and quality of life.
Results Women treated with immediate HRT add-back showed less bone mineral density loss at 6 months and less vasomotor symptoms compared with those who had delayed HRT add-back treatment. Long-term follow up showed both groups experienced equivalent bone mineral density loss. Pain and health-related quality-of-life assessment showed improvement in both groups but there was evidence of a return to baseline levels after ending treatment.
Conclusion Long-term use of GnRH agonist plus immediate add-back HRT is a safe and acceptable approach to intractable cyclical pelvic pain. Given the delay in reactivation of the hypothalamo-pituitary-ovarian axis after long-term suppression, an intermittent dose regime with GnRH agonist might warrant investigation.