Pill Users May Experience Elevated Risk of Crohn's Disease, Ulcerative Colitis

Abstract

A case-control study examined the history of oral contraceptive (OC) use among 91 women in Washington state in the US who had Crohns disease and 211 with ulcerative colitis (forms of inflammatory bowel disease) not caused by infection. The cases and 341 ulcerative colitis controls and 169 Crohns disease controls were interviewed to determine estrogen dosage and duration of use of OCs. The average age at onset of Crohns disease was 31 years and these women were more likely than controls to smoke cigarettes. The average age at onset of ulcerative colitis was 32 years and these women were more likely than controls to be former smokers and to be White. The relative risk of developing Crohns disease was 2.6 for women who had used OCs in the 6 months prior to disease onset as compared to never-users. There was no significant risk among former users but a risk of 7.2 was found among current OC users who had been taking OCs for 6 or more years. A significant trend indicated that increased duration of OC use increased the risk of Crohns disease. Women who used OCs within 6 months of the onset of ulcerative colitis had a 2.0 relative risk compared to never-users. Duration of OC use did not affect the risk of ulcerative colitis however. These risks remained within 10% when controlled for race marital status education income smoking 12 months or more of unprotected intercourse without conception and pregnancy. Stratification of the risk of Crohns disease by estrogen dose and duration of use showed that risk among women with less than 6 years exposure to a high-dose OC was just short of significant with a wide (95%) confidence interval. Both high and low doses of estrogen use for 6 years or more were associated with a sharp increase in the risk of Crohns disease (with extremely wide confidence intervals). Users of high-dose OCs had a significantly greater risk of ulcerative colitis (2.8 for current users and 3.0 for former users) but low-dose OCs caused no increased risk. It was concluded that 17% of the cases of Crohns disease and 28% of the cases of ulcerative colitis in this population could be attributed to OC use.