> ... correlation between UC and a dietary factor?
Environmental factors in inflammatory bowel disease: a co-twin control
study of a Swedish-Danish twin population.
BACKGROUND: Genetics and environmental factors are implicated in the
etiology of inflammatory bowel disease (IBD). We studied environmental
factors in a population-based Swedish-Danish twin cohort using the co-
twin control method. SUBJECTS AND METHODS: A questionnaire was sent to
317 twin pairs regarding markers of exposures in the following areas:
infections/colonization and diet as well as smoking, appendectomy, and
oral contraceptives. Odds ratios (OR) were calculated by conditional
logistic regression. When confounding appeared plausible, multivariate
conditional logistic regression was added. The questions were also
divided into topic groups, and adjustment was made for multiple
testing within each of the groups. RESULTS: The response rate to the
questionnaire was 83%. In consideration of the study design, only
discordant pairs were included (Crohn's disease [CD], n = 102;
ulcerative colitis [UC], n = 125). Recurrent gastrointestinal
infections were associated with both UC (OR, 8.0; 95% confidence
interval [CI], 1.0-64) and CD (OR, 5.5; 95% CI, 1.2-25).
Hospitalization for gastrointestinal infections was associated with CD
(OR, 12; 95% CI, 1.6-92). Smoking was inversely associated with UC
(OR, 0.4; 95% CI, 0.2-0.9) and associated with CD (OR, 2.9; 95% CI,
1.2-7.1). CONCLUSIONS: The observed associations indicate that markers
of possible infectious events may influence the risk of IBD. Some of
these effects might be mediated by long-term changes in gut flora or
alterations in reactivity to the flora. The influence of smoking in
IBD was confirmed. PMID: 17012962
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