Protocol for a placebo-controlled, within-participants crossover trial evaluating the efficacy of intranasal oxytocin to improve pain and function among women with chronic pelvic musculoskeletal pain.

INTRODUCTION: This protocol presents the rationale and design for a trial evaluating the efficacy of intranasal oxytocin in improving pain and function among women with chronic pelvic musculoskeletal pain. Oxytocin is a neuropeptide traditionally recognised for involvement in labour, delivery and lactation. Novel evidence suggests that oxytocin decreases pain sensitivity in humans. While oxytocin administration has been reported to lower pain sensitivity among patients experiencing chronic back pain, headache, constipation and colon pain, no research has evaluated the association between intranasal oxytocin and chronic pelvic musculoskeletal pain. The association between oxytocin and pain may differ in women with chronic pelvic musculoskeletal pain relative to other chronic pain conditions because of the abundance of oxytocin receptors in the uterus. METHODS AND ANALYSIS: This is a prospective, randomised, placebo-controlled, double-blind, within-participants crossover trial. 50 women with chronic pelvic musculoskeletal pain will be recruited through a local chronic pain centre and gynaecology clinics. Women will complete baseline measures and be randomised to an experimental or control condition that involve 2 weeks of self-administering twice-daily doses of 24 IU intranasal oxytocin or placebo, respectively. Women will then undergo a 2-week washout period before crossing over to receive the condition that they had not yet received. The primary outcome will be pain and function measured using the Brief Pain Inventory-Short Form. Secondary outcomes include emotional function, sleep disturbance and global impression of change. This trial will provide data on the 14-day safety and side-effect profile of intranasal oxytocin self-administered as an adjuvant treatment for chronic pelvic musculoskeletal pain. ETHICS AND DISSEMINATION: This trial was granted approval from Health Canada and the University of Calgary Conjoint Health Research Ethics Board, and is registered online at ClinicalTrials.gov (#NCT02888574). Results will be disseminated to healthcare professionals through peer-reviewed publications and to the general public through press releases. TRIAL REGISTRATION NUMBER: NCT02888574; Pre-results.