Appendectomy Raises Risk of Lupus, Especially in Younger Women, Researchers in Taiwan Report

People who have had their appendix surgically removed, particularly younger women, are considerably more likely to develop systemic lupus erythematosus than those who have not had an appendectomy, researchers in Taiwan report.

Women under age 50,  in fact, were found to be at a 2.3 times greater risk of lupus following this surgery, leading the team to recommend that doctors “be aware of the high risk of SLE among young female adults undergoing appendectomy.”

The study, “Women who had appendectomy have increased risk of systemic lupus erythematosus: a nationwide cohort study,” was published in the journal Clinical Rheumatology.

While long seen as a vestigial organ, the appendix is now known to play a role in immune responses, carrying the highest concentration of gut-associated immune cells that act as a fist line of defense against pathogens invading the gastrointestinal tract.

The appendix also harbors a collection of beneficial bacteria capable of promoting the good health of the intestine when needed.

For this reason, an appendectomy is now seen as possibly altering the immune system. Studies have reported an increased risk for autoimmune diseases, like Crohn’s disease or rheumatoid arthritis, following the procedure.

Researchers in Taiwan investigated if an appendectomy also modified the risk for SLE.

They analyzed outcomes in adults who underwent an appendectomy from 2000 to 2011 and were registered in the Taiwan’s National Health Insurance Research Database (NHIRD). As controls, they randomly selected from that database patients who did not have appendectomy.

Their study included 80,582 patients with an appendectomy and 323,850 controls, median age 42, who were followed for a mean of nine years.

Investigators found that appendectomy patients were two times more likely to develop SLE than were controls.

But after stratifying for age and sex, the association only remained significant in women and in patients age 49 or younger. Women overall were 2.09 times more likely to develop lupus if they had had an appendectomy, and the risk rose to 2.3 times among younger women who had the procedure.

The association was also significant after adjusting for occupational status, follow-up time, and urbanization level.

“These findings highlight that appendectomy may be an independent risk factor for SLE, particularly in women aged ≤ 49 years,” the researchers concluded.

They add that this increased higher risk following an appendectomy, seen especially in the first year post-surgery, may suggest that the need for an appendectomy is a marker for undiagnosed SLE.