Effects of acupuncture for the treatment of endometriosis-related pain: A systematic review and meta-analysis

Endometriosis is an estrogen-dependent inflammatory gynecologic condition that affects 5-15% of women of reproductive age, causing severe chronic pelvic pain and infertility. Conventional treatments include hormonal therapies and surgery, but they frequently produce significant adverse effects and inadequate pain relief. This systematic review and meta-analysis investigated the efficacy of acupuncture as an alternative or complementary treatment for endometriosis-related pain. The investigators conducted a comprehensive search across six databases through December 2016, identifying randomized controlled trials that compared acupuncture with other treatments.

Ten studies with 589 participants were included, with 295 in the acupuncture group and 294 in the control groups. Study quality was assessed using Cochrane criteria. Most studies compared acupuncture with Western medicine (danazol, mifepristone, goserelin acetate) or traditional Chinese medicine, with only one study using an adequate placebo control. The most commonly used acupuncture points included CV-3, CV-4, CV-6, SP-6, BL-18, BL-20, and the extra Zigong points.

Results demonstrated that acupuncture was superior to controls in three primary outcomes. For pain reduction, measured on a 0-10 point scale, acupuncture showed a mean difference of 1.36 points favoring the experimental group (95% CI: 1.01-1.72, p<0.0001). In the only placebo-controlled study, the acupuncture group experienced a mean pain reduction of 4.8 points compared with 1.4 points in the control group (p=0.004). Regarding CA-125 levels, an inflammatory marker elevated in endometriosis, acupuncture significantly reduced serum levels by 5.9 U/mL compared with controls (95% CI: 1.56-10.25, p=0.008).

The clinical efficacy rate also favored acupuncture, with an odds ratio of 2.07 (95% CI: 1.24-3.44, p=0.005). Proposed mechanisms include activation of descending pain inhibitory systems, release of analgesic neurotransmitters, hormonal modulation with estradiol suppression, and improved immune function through increased natural killer (NK) cell activity. Despite these promising results, the review has important limitations: only one trial was adequately blinded, sample sizes were small (8-36 patients per arm), and methodologic heterogeneity was considerable. Three of the included studies were unpublished theses not subject to peer review.

Inadequate implementation of blinding and allocation concealment may have inflated the observed therapeutic effects. The clinical implications suggest that acupuncture may be a safe and well-tolerated adjunctive therapy for women with endometriosis-related pain, particularly when conventional treatments are inadequate or cause unacceptable adverse effects. The persistence of pain relief for up to 6 months after treatment, observed in the placebo-controlled study, is particularly encouraging. However, additional randomized, double-blind trials with adequate sample sizes and appropriate placebo controls are needed to definitively confirm these findings and establish standardized treatment protocols.