Risk factors for inflammatory bowel disease in the general population

Authors


Dr A. González-Pérez, C/Almirante 28-2, 28004 Madrid, Spain.
E-mail: agonzalez@ceife.es

Summary

Background:  The aetiology of inflammatory bowel disease remains largely unknown.

Aim:  We performed a comprehensive assessment of potential risk factors associated with the occurrence of inflammatory bowel disease.

Methods:  We identified a cohort of patients 20–84 years old between 1995 and 1997 registered in the General Practitioner Research Database in the UK. A total of 444 incident cases of IBD were ascertained and validated with the general practitioner. We performed a nested case–control analysis using all cases and a random sample of 10 000 frequency-matched controls.

Results:  Incidence rates for ulcerative colitis, Crohn's disease, and indeterminate colitis were 11, 8, and 2 cases per 100 000 person-years, respectively. Among women, we found that long-term users of oral contraceptives were at increased risk of developing UC (OR: 2.35; 95% CI: 0.89–6.22) and CD (OR: 3.15; 95% CI: 1.24–7.99). Similarly, long-term users of HRT had an increased risk of CD (OR: 2.60; 95% CI: 1.04–6.49) but not UC. Current smokers experienced a reduced risk of UC along with an increased risk of CD. Prior appendectomy was associated with a decreased the risk of UC (OR: 0.37; 95% CI: 0.14–1.00).

Conclusions:  Our results support the hypothesis of an increased risk of inflammatory bowel disease associated with oral contraceptives use and suggest a similar effect of hormone replacement therapy on CD. We also confirmed the effects of smoking and appendectomy on inflammatory bowel disease.

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