Both oral contraceptives and hormone replacement therapy may increase risk of irritable bowel disease

Robin Wulffson MD's picture
inflammatory bowel disease, IBD, Crohn's disease, ulcerative colitis, HRT
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According to new studies, both oral contraceptives and hormone replacement therapy (HRT) may increase the risk of developing inflammatory bowel disease (IBD). Researchers affiliated with Massachusetts General Hospital in Boston presented their findings May 21 at the Digestive Disease Week conference in San Diego, California.

Two large studies found a link between oral contraceptives and Crohn's disease but not ulcerative colitis. Interestingly, a related study of postmenopausal women found an association between HRT and ulcerative colitis but not Crohn's disease. The two major types of IBD are ulcerative colitis and Crohn’s disease (CD). Ulcerative colitis is limited to the colon. Crohn’s disease can involve any segment of the gastrointestinal tract from the mouth to the anus.

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The researchers derived their data from 117,935 women in the Nurses’ Health Study I, which ran from 1976 to 2008, and the Nurses’ Health Study II, which ran from 1989 to 2005 and comprised 114,794 women. The combined studies produced 5,323,303 person years of follow-up; 309 new cases of Crohn's disease and 362 new cases of ulcerative colitis occurred. The researchers found that current users of oral contraceptives appeared to have the highest risk for Crohn's disease (2.66 times greater); however, past users also had elevated risk (1.40 times greater). As previously noted, oral contraceptive users had no increased risk of ulcerative colitis.

The HRT study, which had opposite findings to those of the oral contraceptive study, was comprised of 108,589 postmenopausal US women who enrolled in 1976 in the Nurses’ Health Study. At entrance into the study, the women had no history of IBF; their average age was 54 years. Through 2008, the researchers accrued a total of 1,891,153 person years of follow up; during this period, 138 cases each of Crohn's disease and ulcerative colitis. An increased risk of ulcerative colitis was found among current HRT users (1.74 times greater risk); an increased risk was also found among past HRT users (1.68 times greater risk). In addition to a lack of association with Crohn’s disease, the type of HRT did not appear to affect the risk of IBD.

Take home message:
Genetic factors are involved in the development of IBD; therefore, individuals with a family history of either ulcerative colitis or Crohn’s disease and are taking hormonal therapy should be aware of this study’s findings. All medications have both risks and benefits; thus, this study suggests a possible increase risk of hormonal therapy for those with a family history of IBD. A decision as to whether to take any type of hormonal therapy should be made with consultation from a healthcare professional.

Reference:
Digestive Disease Week

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