But treatment with the GnRH agonist costs nearly 20 times more than oral contraceptives (OCs), and requires periodic intramuscular injections, the authors point out in their report, posted online February 5th in Fertility and Sterility. However, the only approved treatment for endometriosis pain is the GnRH analog leuprolide with hormonal add-back using oral norethindrone acetate.
The randomized, double-blind, double-dummy study originally included 47 patients with moderate to severe pelvic pain due to endometriosis enrolled at two sites (Boston and Rochester, New York), but seven patients withdrew prior to receiving study drug. At 24 weeks, 16 in the OC group and 13 in the leuprolide group remained. At study’s end, there were 14 and 11 patients, respectively.
Dr. David S. Guzick, at the University of Florida Health Science Center, Gainesville, first author on the study, and his associates assigned 21 patients to leuprolide 11.25 mg IM every 12 weeks with norethindrone 5 mg daily. They assigned the remaining 26 subjects to a generic daily oral contraceptive (1 mg norethindrone + 35 mcg ethinyl estradiol).
During the 48-week trial, clinicians assessed the patients for pain, quality of life, and psychosocial functioning at baseline and then every 12 weeks.
Pain assessments included the Biberoglu and Behrman patient ratings (B&B pain score; 0 to 3 points each for dyspareunia, dysmenorrhea, and noncyclic pelvic pain; higher scores = more pain), and the numerical Rating Scale (NRS; 1-10 points, higher score = greater pain).
Based on both pain scales, both treatment groups reported significant improvements at each time point after baseline, with no significant difference between groups.
Patterns of response were similar for the Beck Depression Inventory (21-item instrument in which higher scores indicate more symptoms of depression) and for the Index of Sexual Satisfaction (25 item, lower score = greater satisfaction).
Dr. Guzick and associates estimate that the cost of leuprolide/norethindrone at approximately $8000 for 48 weeks, while the generic OCs would add up to $454. Thus, a 48-week treatment course of OCs would save more than $7,000 per patient.
There were no significant adverse events, the report shows, with roughly equal numbers of patients experiencing vaginal bleeding and hot flashes.
The authors conclude that their data “support the use of continuous OCs as first-line therapy in the medical treatment of endometriosis-associated pelvic pain.”
Fertil Steril 2011.