Pelvic Pain Symptoms and Inflammation Among Adolescents and Adults with and Without Endometriosis

We evaluated inflammatory markers among 389 surgically confirmed endometriosis cases and 505 controls from the Women's Health Study: From Adolescence to Adulthood (A2A) cohort. Participants reported dysmenorrhea, acyclic pelvic pain, dyspareunia, and pain with bowel movements. Using multiplex assays, we measured their levels of plasma interleukin (IL)-1β, -6, -8, -10, and -16, tumor necrosis factor (TNF)-α, monocyte chemotactic protein (MCP)-1 and -4, thymus and activation-regulated chemokine (TARC), and interferon gamma-induced protein (IP)-10. For each symptom, we computed biomarker-level geometric means (GMs) with 95% confidence intervals (95% CI) using multivariate linear regression among the endometriosis cases and controls, with interactions with case/control status tested using Wald statistics. Among the controls, those with dyspareunia had lower levels of IL-8 (GM_present = 4.64 [95% CI = 4.41-4.89] pg/mL vs. GM_absent = 4.99 [95% CI = 4.82-5.17] pg/mL; p = 0.02), and the IL-8 levels were lower for controls reporting pain with bowel movements (GM_present = 4.66 [95% CI = 4.43-4.89] vs. GM_absent = 4.96 [95% CI = 4.82-5.11] pg/mL, p = 0.03). No significant associations between pelvic pain symptoms and inflammatory markers were observed among the endometriosis cases; however, the relationship between inflammatory marker levels and pain experience varied by analgesic use at blood draw. Dyspareunia and pain with bowel movements were associated with inflammatory markers among the controls, while the associations between pelvic pain symptoms and inflammatory markers among the endometriosis cases differed by analgesic use.