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Passive smoking is associated with an increased risk of developing inflammatory bowel disease in children
B A Lashner1, N J Shaheen, S B Hanauer
1Department of Medicine, University of Chicago Medical Center, Illinois.
Insights
Secondhand smoke exposure, including maternal smoking at birth, significantly increases children's risk of developing inflammatory bowel disease (IBD). This risk is higher for Crohn's disease than ulcerative colitis, with a clear dose-response relationship observed.
Area of Science:
- Pediatric Gastroenterology
- Environmental Health
- Epidemiology
Background:
- Adult smoking influences inflammatory bowel disease (IBD) risk, with Crohn's disease (CD) linked to smoking and ulcerative colitis (UC) protected by it.
- Children, often non-smokers, may face IBD risks from passive smoke exposure, necessitating investigation into early-life environmental factors.
Purpose of the Study:
- To investigate the association between passive smoking exposure and the development of IBD in children.
- To differentiate the impact of passive smoking on Crohn's disease versus ulcerative colitis in pediatric populations.
Main Methods:
- A matched case-control study involving 72 children with recently diagnosed IBD (39 UC, 33 CD) and 72 controls.
- Assessment of passive smoking exposure at birth and symptom onset, including maternal smoking habits and daily pack consumption.
Main Results:
- Passive smoking exposure at birth was significantly associated with IBD development (OR 3.02), with a stronger effect in Crohn's disease (OR 5.32) than ulcerative colitis (OR 2.19).
- Maternal smoking at birth also showed a significant association with IBD (OR 2.09), again more pronounced in Crohn's disease.
- A dose-response relationship was observed between passive smoking (packs per day, packs at home) and IBD risk, including at symptom onset (OR 1.88).
Conclusions:
- Passive smoking, particularly maternal smoking during pregnancy and at birth, is a significant risk factor for pediatric IBD.
- The association between passive smoking and IBD is stronger for Crohn's disease than ulcerative colitis.
- Evidence suggests inhaled toxins are the primary route of exposure, rather than placental transfer or breastfeeding.
Abstract:
Adult cigarette smoking is associated with the development of Crohn's disease and protection from the development of ulcerative colitis. Children usually are nonsmokers whose risk of developing inflammatory bowel disease (IBD) may be related to passive smoking. The purpose of this matched case-control study was to evaluate passive smoking exposure in 72 nonsmoking children with recently diagnosed IBD (39 with ulcerative colitis and 33 with Crohn's disease), and in an equal number of peer-nominated controls. Passive smoking exposure at birth was significantly associated with the development of IBD (odds ratio 3.02, 95% confidence interval 1.28-7.06). The effect was greater in Crohn's disease (odds ratio 5.32) than in ulcerative colitis (odds ratio 2.19). Maternal smoking at birth also was significantly associated with the development of IBD (odds ratio 2.09, 95% confidence interval 1.02-4.29), an effect that also was greater in Crohn's disease than in ulcerative colitis. There was a dose-response relationship between packs smoked per day and IBD, and packs smoked at home per day and IBD. At symptom onset, the risk of developing IBD from passive smoking exposure was increased but was not significant (odds ratio 1.88, 95% confidence interval 0.84-4.18). The magnitude of the effect was greater in Crohn's disease than in ulcerative colitis, and the association demonstrated dose-response. In conclusion, passive smoking exposure and maternal smoking at birth and, to a lesser extent, passive smoking exposure at symptom onset are associated with an increased risk of developing IBD in children. The association is stronger in Crohn's disease than in ulcerative colitis, and there is a dose-response effect. The specific toxic exposure is more likely to be inhaled rather than passed through the placenta or in breast milk.