Impact of elagolix treatment on fatigue experienced by women with moderate to severe pain associated with endometriosis

Objective To evaluate the efficacy of elagolix, an oral GnRH antagonist, for the reduction of fatigue in women with moderate or severe endometriosis-associated pain. Design Randomized, double-blind, multicenter, placebo-controlled phase III trial. Setting Clinics. Patient(s) A total of 860 women treated with elagolix or placebo. Intervention(s) Women received either elagolix at 150 mg daily (QD) orally, elagolix at 200 mg twice daily (BID) orally, or placebo. Main Outcome Measure(s) Change from baseline to month 1, 3, and 6 visits, in Patient-Reported Outcomes Measurement Information System (PROMIS) Fatigue Short Form 6a questionnaire T-scores. Results(s) At baseline, 54%–74% of women with moderate to severe pain associated with endometriosis reported having fatigue-related issues "quite a bit" or "very much," depending on the question asked. Fatigue extent was reduced to 29%–43% and 14%–29% for women treated with elagolix at 150 mg QD and 200 mg BID, respectively, at 6 months, compared with 35%–50% with placebo. The resultant decrease in fatigue T-scores was significant after elagolix treatment compared with placebo at 6 months, with changes of −2.21 and −5.90 with elagolix at 150 mg QD and 200 mg BID, respectively. Significant reduction in fatigue scores were observed among patients reporting clinically meaningful response "reduction" in dysmenorrhea, nonmenstrual pelvic pain, and dyspareunia (−7.31, −6.62, and −4.31, respectively) compared with nonresponders. Conclusion(s) In women with moderate to severe endometriosis related pain, elagolix significantly reduces fatigue levels.