An association between endometriosis and certain autoimmune diseases has been suggested.
However, the impact of endometriosis on risk of inflammatory bowel disease (IBD) remains unknown.
Dr Tine Jess and colleagues from Denmark assessed the risk of Crohn's disease and ulcerative colitis in an unselected nationwide Danish cohort of women with endometriosis.
By use of national registers, the team identified 37,661 women hospitalized with endometriosis during 1977–2007.
|Women with endometriosis had a increased risk of IBD overall|
The relative risk of developing IBD after an endometriosis diagnosis was calculated as observed versus expected numbers, and presented as standardized incidence ratios (SIRs) with 95% CIs.
The research team found that women with endometriosis had a increased risk of IBD overall, and of ulcerative colitis and Crohn's disease separately, even 20 years after a diagnosis of endometriosis.
The team observed that restricting analyses to women with surgically verified endometriosis suggested even stronger associations.
Dr Jess' team concludes, "The risk of IBD in women with endometriosis was increased even in the long term, hence suggesting a genuine association between the diseases, which may either reflect common immunological features or an impact of endometriosis treatment with oral contraceptives on risk of IBD."