The Overlap Between Lupus and Endometriosis

The Hidden Connection Between Systemic Lupus and Endometriosis

The interconnectedness of various ailments, based on possible shared characteristics and pathogenesis, has become a focal point of research. Endometriosis and lupus exemplify this relationship, as two seemingly unrelated conditions that share intriguing parallels. This article explores the increased risk of being diagnosed with endometriosis in patients suffering from Systemic Lupus Erythematosus (SLE), with the aim of uncovering links that may lead to treatment discoveries.

Understanding Endometriosis

Endometriosis is a multifaceted disease that primarily affects women in their reproductive years. It is characterized by the abnormal growth of endometrial-like tissue outside the uterus, leading to chronic pelvic pain and potential infertility. The pathophysiology of endometriosis involves a systemic inflammatory response, influenced by female sex hormones that may subtly affect the maintenance of immunity or the development of autoimmune diseases.

Getting to Know Systemic Lupus Erythematosus (SLE)

SLE is a chronic autoimmune disease that can affect various parts of the body, including the skin, joints, kidneys, heart, and lungs. It involves the immune system attacking the body’s own tissues, causing inflammation and damage. Women, particularly those of childbearing age, are more frequently diagnosed with SLE than men. Additional factors such as ethnicity, age of onset, and socioeconomic class significantly influence SLE incidence, with notable geographic differences observed.

Endometriosis and SLE: The Intriguing Association

Epidemiological studies suggest a solid link between endometriosis and female-dominant autoimmune diseases. That said, not all investigations support a significant association specifically between endometriosis and SLE. The potential for spurious associations remains high due to small study sizes and suboptimal control selection.

Unraveling the Connection: A Comprehensive Study

To address these inconsistencies—and acknowledging that findings may not be generalizable across all geo-ethnic populations—a large nationwide retrospective cohort study was conducted to assess the risk of endometriosis in women diagnosed with SLE. The analysis used data from the Taiwan Longitudinal Health Insurance Research Database 2000 (n = 958,349) over a 13-year follow-up period (2000–2013).

Study Design and Population

This retrospective cohort study drew primary data from the Taiwan National Health Insurance Research Database (NHIRD). The study cohort included women diagnosed with SLE between 1997 and 2013, with the index date defined as the first diagnosis of SLE.

Assessed Outcome

The primary outcome was the diagnosis of endometriosis. Because non-invasive diagnostic tools for endometriosis are limited, diagnoses were derived from clinical evidence or surgical intervention. Every effort was made to optimize parameters of non-surgical diagnosis of endometriosis; however, surgical validation was lacking for a large number of subjects, representing a significant study weakness.

Results and Implications

Within the stated limitations, the study found a statistically significant association between SLE and endometriosis after controlling for age.

Conclusion: A Call for Further Research

In this study, the risk of endometriosis was significantly higher in SLE patients compared to the general population, adding substantially to the broader body of evidence supporting an association. Further research is needed to fully understand this relationship and to determine its applicability across different geo-ethnic populations. In parallel, more basic science research is critically needed to support epidemiologic findings.