Probiotics in the Management of Endometriosis: A Meta-Analysis and Review of the Literature

INTRODUCTION: Endometriosis affects 6–10% of women and may cause pelvic pain with significant impact on quality of life. In addition, many patients do not respond to first-line hormonal suppressive therapies and may necessitate GnRH-targeting agents or surgery, which may subsequently have adverse effects, impact quality of life, and impose notable financial burden for patients and the healthcare system. As with other chronic inflammatory conditions, numerous studies have demonstrated a correlation between gut dysbiosis and endometriosis. Specifically, decreased lactobacilli concentrations and increased firmicute-to-bacteriodetes ratio have been observed and may affect inflammation and enteric estrogen metabolism and reabsorption, resulting in exacerbation of endometriosis. Targeting gut dysbiosis with a low-cost intervention of probiotics may be promising to improve pelvic pain from endometriosis and improve quality of life. OBJECTIVE: This meta-analysis reviews the existing research on the effect of probiotic supplementation on pelvic pain and quality of life in patients with endometriosis. METHODS: A systematic review and meta-analysis were performed to identify trials that evaluated pelvic pain (outcome) with visual analog score (VAS), among patients with endometriosis, as an outcome of probiotic supplementation (intervention). Two randomized controlled trials were identified (n=2 of 99) evaluating 8 and 12 week (respectively) daily probiotic (lactobacillus supplementation) compared to placebo. Quality of evidence and risk of bias was assessed using the Cochrane Risk of Bias in Randomized Trials (RoB 2.0) tool. No detectable between-study heterogeneity was identified. A fixed-effect model was utilized to analyze mean difference (MD) in pelvic pain (VAS) between probiotic intervention and placebo. RESULTS: The Risk of Bias (RoB 2.0) tool was used to establish low publication bias for the two randomized control trials. A pooled MD of –1.28 (95% CI –1.44 to –1.12) was identified demonstrating significant reduction of pelvic pain in favor of probiotic supplementation intervention in relation to placebo after 8 weeks of intervention. One of the trials evaluated pelvic pain (VAS) after 8 weeks of intervention followed by 4 weeks without supplementation or placebo and identified a non-significant MD of –1.28 (95% CI –1.61 to –0.95). No adverse outcomes were identified. CONCLUSIONS: Probiotic supplementation may be a promising low-risk intervention to reduce pelvic pain among patients with endometriosis, but future research is encouraged in the setting of limited data.