MedWire News: People who have undergone appendix-removal surgery, called an appendectomy, face an increased risk of being diagnosed with Crohn's disease up to 5 years after the operation, researchers have found.

Dr Gilaad Kaplan, from University of Calgary in Alberta, Canada, and team explain that a number of studies had indicated that appendix-removal surgery is associated with a reduced risk of ulcerative colitis.

But they add that studies examining the relationship between appendectomy and Crohn's disease have produced conflicting results.

To investigate further, the researchers reviewed the results of 18 published studies that contained data on Crohn's disease diagnoses after appendectomy.

Analysis of the pooled results revealed that, overall, patients who had undergone an appendectomy were around 1.6 times more likely to develop Crohn's disease than those who had not undergone the operation.

Further analysis revealed that, compared with patients who had not undergone an appendectomy, those who had were more than six times more likely to develop Crohn's disease within a year of the operation, and around twice as likely to develop the disease 1-4 years after the procedure.

However, after 5 years, the risk of Crohn's disease among appendectomy patients was similar to that in those who had not undergone appendix-removal surgery.

Writing in the American Journal of Gastroenterology, Dr Kaplan and team comment that that their findings "demonstrated a significant risk of Crohn's disease following an appendectomy".

However, the researchers add that, instead of a biological link between the two disorders, the findings may reflect the fact that patients with early, undiagnosed Crohn's disease are more likely to mistakenly receive appendix-removal surgery than other people.

"A considerable proportion of the risk of developing Crohn's disease was observed within the first year following an appendectomy, a time when incipient Crohn's disease may lead to undue appendectomies", they conclude.