Regarding the categories for the IL-1β levels, the endometriosis cases who experienced dysmenorrhea often/usually were 79% less likely to be in the category with the highest IL-1β levels (between the median and highest values) compared to the endometriosis cases who always experienced dysmenorrhea (odds ratio (OR): 0.21; 95% CI: 0.06–0.74; Table S6). This evidence concerns the gene IL1B and endometriosis.