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

Fertil Steril. 2019 Aug;112(2):298-304.e3. doi: 10.1016/j.fertnstert.2019.02.031. Epub 2019 Apr 13.


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.

Trial registration: NCT01620528 NCT01760954.

Keywords: Endometriosis; elagolix; fatigue; gonadotropin-releasing hormone antagonist.

Publication types

  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Double-Blind Method
  • Endometriosis / complications
  • Endometriosis / drug therapy*
  • Fatigue / drug therapy*
  • Fatigue / etiology
  • Female
  • Gonadotropin-Releasing Hormone / antagonists & inhibitors
  • Hormone Antagonists / therapeutic use
  • Humans
  • Hydrocarbons, Fluorinated / therapeutic use*
  • Middle Aged
  • Pain Measurement
  • Pelvic Pain / drug therapy*
  • Pelvic Pain / etiology
  • Pelvic Pain / pathology
  • Placebos
  • Pyrimidines / therapeutic use*
  • Severity of Illness Index
  • Treatment Outcome
  • Uterine Diseases / complications
  • Uterine Diseases / drug therapy*
  • Young Adult


  • Hormone Antagonists
  • Hydrocarbons, Fluorinated
  • Placebos
  • Pyrimidines
  • Gonadotropin-Releasing Hormone
  • elagolix

Associated data