Background: The highest prevalence of smoking in the United States is in Kentucky, where smoking typically begins in childhood. The state has many patients who suffer from inflammatory bowel diseases (IBD). The primary aim of this study was to assess whether exposure to active and/or passive tobacco smoke in childhood is related to the likelihood of developing IBD.
Methods: Recruited into this prospective study were a total of 672 participants (253 patients with Crohn's disease [CD], 177 patients with ulcerative colitis [UC], and 242 controls), all of whom were asked to complete the Behavioral Risk Factor Surveillance Survey modified by the addition of 4 questions on childhood passive smoke exposure.
Results: Survey response rate was 84%. CD and UC patients were more likely than controls to begin smoking regularly by ages 10 and 15, respectively, suggesting that becoming a regular smoker at a younger age may be associated with a subsequent diagnosis of IBD. Smoking by age 10 was associated with an earlier age at diagnosis with UC, but not with CD. CD patients were more likely than controls to have prenatal smoke exposure (odds ratio [OR], 1.72; 95% confidence interval [CI], 1.1-2.71) and were more likely to have passive smoke exposure during childhood, with 1 or both parents or other household members being smokers (OR, 2.04; 95% CI, 1.28-3.31).
Conclusions: Passive and active smoke exposure in childhood influences the development of IBD. A high incidence of this disease in a state with a high rate of cigarette smoking underscores the profound role of environmental factors in the etiology of these illnesses.