Significant Association Found Between Endometriosis and Systemic Lupus Erythematosus

young woman in pain
Researchers examined the association between endometriosis and the risk for systemic lupus erythematosus.

An increased risk for systemic lupus erythematosus (SLE) was found among patients with endometriosis, according to study results published in Scientific Reports.

Recent studies have demonstrated a higher prevalence of allergies and autoimmune diseases among patients with endometriosis. Researchers of the current nationwide, population-based, retrospective cohort study sought to examine the association between endometriosis and risk for SLE

They used data from Taiwan’s National Health Insurance Research Database (NHIRD), which was established by the National Health Insurance (NHI) program. The Longitudinal Health Insurance Database served as the dataset for the study cohort, yielding a sample of 1 million participants from 23 million beneficiaries of the NHIRD. The index date of the cohort was the date of the initial endometriosis diagnosis, with the outcome measurement being the diagnosis of SLE and use of hydroxychloroquine for 1 year. The study endpoint was the occurrence of SLE or withdrawal from the NHI program, whichever occurred first.

Researchers initially matched individuals with vs without endometriosis in a 1:6 ratio. They conducted propensity score matching by accounting for covariates, such as age, comorbidities, use of corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), and hormonal medications, to control confounding between the endometriosis and nonendometriosis groups. Overall, after matching, 16,758 participants from both the endometriosis group and nonendometriosis group were enrolled in the study.

Results of the study revealed that individuals in the endometriosis vs nonendometriosis group had a significantly higher incidence density rate of SLE (0.3 vs 0.1 per 1000 person-years) and adjusted hazard ratio (aHR, 2.37; 95% CI, 1.35-4.14). Researchers did not observe any significant effects of age, hypertension, chronic liver disease, uses of corticosteroids, NSAIDs, and hormonal medications in the HR/aHR of SLE. They observed a similar association in the sensitivity analysis, with a significantly higher aHR for SLE among patients with laparoscopically diagnosed endometriosis (aHR, 4.74; 95% CI, 1.07-20.93).

According to subgroup analyses, patients with endometriosis aged between 30 and 45 years, those receiving NSAIDs, and those who were not receiving hormonal medications all had higher risks for SLE. Among patients with endometriosis, surgical intervention did not significantly affect the risk for SLE.

Researchers concluded that clinicians should be aware of the association between endometriosis and SLE when managing patients with these conditions. “However, further basic medical [research] are needed to clarify the link and mechanisms between endometriosis and SLE,” they added.


Fan Y-H, Leong P-Y, Chiou J-Y, Wang Y-H, Ku M-H, Wei JC-C. Association between endometriosis and risk of systemic lupus erythematosus. Sci Rep. 2021;11(1):532. doi:10.1038/s41598-020-79954-z