Appendicectomy, childhood hygiene, Helicobacter pylori status, and risk of inflammatory bowel disease: a case control study.

AIMS: To examine the relation between inflammatory bowel disease and appendicectomy, childhood domestic hygiene, and Helicobacter pylori infection.
METHODS: Case control study involving 213 patients with ulcerative colitis, 110 with Crohn's disease, and 337 controls having elective surgery.
RESULTS: Nine patients with ulcerative colitis (4.5%) reported a previous appendicectomy compared with 57 controls (19%) (odds ratio (OR) 0.20, 95% confidence interval (CI) 0. 1-0.4, p<0.0001). The inverse association was unaffected by excluding operations performed after the age of onset of ulcerative colitis and was stronger for appendicectomy performed before age 20 (OR 0.14). No association with appendicectomy was found for Crohn's disease and no associations with tonsillectomy for either disease. The availability of a fixed hot water supply in early childhood (before age 11) was associated with Crohn's disease (OR for hot water not always versus always available 0.56, 95% CI 0.3-0.9, p=0. 02) but not with ulcerative colitis. No other aspect of domestic hygiene before or after age 11 was associated with either Crohn's disease or ulcerative colitis. Although H pylori seroprevalence was positively associated with overcrowding (p<0.001) and the absence of running hot water in childhood it was not associated with the presence of either Crohn's disease or ulcerative colitis. H pylori seroprevalence was no lower in patients who had been exposed to sulphasalazine than in controls or those not exposed.
CONCLUSIONS: Our findings confirm the strong inverse association between previous appendicectomy and the development of ulcerative colitis and suggest that the protective effect is greater for appendicectomy performed in childhood.