105 DIAGNOSIS OF CROHN'S DISEASE IS ASSOCIATED WITH INCREASED LEVELS OF ANTIBIOTIC USE OVER THE PRECEEDING FIVE YEARS

T.R. Card¹, R.F.A. Logan¹, L.C. Rodrigues², J.G. Wheeler².¹Division of Public Health Sciences, University of Nottingham, Queen's Medical Centre; ²London School of Hygiene and Tropical Medicine, UK

Background: Although it is generally accepted that Crohn's disease has both genetic and environmental determinants, few environmental determinants are well established. In view of the widely supported notion that dysfunction of the gut is inter-linked with its flora, we explored the potential importance of the use of antibiotics as a risk factor.

Methods: We selected records of incident cases of Crohn's disease from the General Practice Research Database. All cases were diagnosed after 1992, had no history of Ulcerative Colitis and at least five years of GPRD data prior to diagnosis. Controls with five years complete data were randomly selected. Data were extracted on smoking, presentation to GP with a diagnosis of infection, oral contraceptive use (OCP) and antibiotic use 3–5 years prior to the date of diagnosis of Crohn's disease (and for a comparable period for controls). Data on antibiotic use was restricted in time to exclude those that could have been prescribed as treatment of premonitory symptoms. Logistic regression was used to investigate the relationship between antibiotic use and Crohn's disease.

Results: 601 Crohn's disease and 1460 controls were available for analysis. We found statistically significant associations between Crohn's disease and use of OCP in the year before diagnosis (Odds ratio 1.7, P=0.003) and smoking (Odds ratio 1.5, P=0.001) despite incomplete data for the latter (these are consistent with the literature). Antibiotic use 3–5 years pre-diagnosis was significantly greater in cases than controls. Only 29% of cases compared to 42% of controls received no antibiotics (P<0.001), and the mean number of courses was 2.6 in cases and 1.9 in controls (P<0.0001). …