Design: Systematic review and meta-analysis

Setting: Endometriosis research

Patients or Participants: Articles related to IL serum levels in individuals with and without endometriosis through May 2023.

Interventions: Each article was evaluated for inclusion, data were extracted, and meta-analysis was performed.

Measurements and Main Results: Thirty studies met inclusion criteria. These studies included IL-1Ra, IL-1b, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17A, IL-18, IL-23, and IL-37. Patients with endometriosis were found to have higher serum levels of IL-1Ra, IL-6, and IL-37 compared to those without endometriosis. They were found to have lower serum levels of IL-23 as compared to patients without endometriosis. The serum levels of IL-6 were 1.38 SDs higher in those with endometriosis than in those without endometriosis (study n=16 Hedges’ g effect size = 1.38, 95% CI 0.58−2.17 , I < .001, I²=97.19%). Meta-regression suggested that IL-6 in endometriosis was not significantly impacted by the stage (I/II vs. III/IV) of the disease (Hedge’s g effect size; Regression coefficient = −0.53, 95% CI−1.44 to 0.38, p=.253, change in R² = 2.89%).

Conclusion: There is evidence supporting the association of serum IL levels, particularly IL-6, with endometriosis. This suggests that treatment and diagnostic studies related to these inflammatory pathways may be effective for patients with endometriosis.