RESUMEN
BACKGROUND: Osteoarthritis of the knee is a major cause of disability among adults. Electro-acupuncture is considered a potentially useful treatment for osteoarthritis. The purpose of this study is to assess the efficacy of electro-acupuncture on pain control, pain perception, plasma cortisol and beta-endorphin levels, patient-perceived quality of life, and pain medication use in patients with chronic knee pain. METHODS/DESIGN: This study is a placebo-controlled, randomized, double-blind, parallel design trial. One hundred sixty out-patients who are more than 50 years old and who have osteoarthritis of the knee will be recruited from the island of Mallorca, Spain. Each participant will be randomly placed into one of two groups: (sham) electro-acupuncture non-insertion technique and real electro-acupuncture. Acupuncture treatments will be the Traditional Chinese Medicine type. The patients will be evaluated after a period of 1 month (with two weekly sessions), 3 months (with one monthly session), 6 months (with one session every 45 days), and 1 year later with follow-up sessions at the end of the study (with one session every 2 months). The primary outcomes will be based on the observed changes from the baseline of the visual analogue scale (VAS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for pain measured at 12 weeks after the end of treatment. Also to be included in the study are the possible changes in the secondary efficacy variables from baseline as assessed by the Short Form 36 version 2 health survey (patient-perceived quality of life), patient plasma cortisol and beta-endorphin levels at the different treatment stages, the Goldberg Anxiety and Depression Scale, pain medication use, functional capacity and stiffness (WOMAC subscales), and a VAS. These variables will be assessed at 1 month, 3 months, 6 months, and 1 year after study commencement. DISCUSSION: The findings from this study will help to determine whether electro-acupuncture is effective for chronic knee pain management in older people and whether electro-acupuncture can deliver results for the improvement of pain relief, stiffness, and disability. The study will therefore be a major step toward understanding the roles of the hypothalamic-pituitary-adrenal axis and the endogenous opioid system in the effectiveness of electro-acupuncture for chronic pain. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02299713 (11 Nov. 2014).