In this month’s Gastroenterology, two articles offer some insight into this question for two separate problems.
With regard to inflammatory bowel disease, (IBD) –both Crohn’s disease and UC –there is an increasing prevalence and incidence worldwide (Gastroenterology 2012; 142: 46-54). This article identified 8444 previous citations and then identified 262 studies with relevant data. Overall, the highest incidence and prevalence of these disorders occurs in Europe and North America. In North America, Canada has the highest prevalence with 0.6% of the population having IBD.
After going through the statistics, the authors offer some discussion on why IBD is increasing. In the developing parts of the world, some of the increase is due to the ability to detect and differentiate these disorders due to improving access to medical care/colonoscopy. In the areas of the world with the highest incidence/prevalence, environmental risk factors are playing an important role. Potential factors include microbial exposures, sanitation, lifestyle behaviors, medications, and pollution. These factors are supported by other epidemiological studies which show that individuals who move from low prevalence areas to higher ones are at increased risk for IBD, especially among first generation children (Gut 2008; 57: 1185-91). Furthermore, in low prevalence regions, IBD is increasing with more industrialization (Chin J Dig Dis 2005; 6: 175-81, Indian J Gastroenterol 2005; 24: 23-24.) Exact mechanisms are poorly understood; however, even in the U.S. it is recognized that rural/farm exposure at a young age reduces the likelihood of developing IBD at a later age (Pediatrics 2007; 120: 354).
Celiac disease, likewise, has seen an increase in prevalence. With celiac disease, the proliferation of widely available and more accurate serology has been crucial in the identification of more patients. However, like IBD, there is likely a role for changing microbial environment contributing to an increasing case burden. Recently, reports have shown that the risk of celiac disease can be influenced at birth (Gastroenterology 2012; 142: 39-45). Although the absolute risk was modest, there was an increased risk demonstrated with elective but not emergent cesarean delivery among a large nationwide case-control study from Sweden. Among the cohort of 11,749 offspring with biopsy-proven celiac (with matched control group of 53,887), elective cesarean delivery resulted in an odds ratio of 1.15 (confidence intervals 1.04-1.26). This study confirmed other studies which have shown an increased risk with cesarean delivery (Pediatrics 2010; 125: e1433-e1440). Some of the strengths of this Swedish study, included the fact that the deliveries were separated based on elective or emergency cesarean delivery and were controlled for whether the mother had celiac disease. (Pregnant women with celiac disease have an increased risk of cesarean delivery.) The authors speculate that the reason why elective cesarean deliveries increase the risk of celiac disease is that microbial exposures at birth likely influences perinatal colonization –>affects intestinal immune response and mucosal barrier function. Offspring of women with emergency cesarean delivery would be more likely to be exposed to bacteria from the birth canal and no significant increase risk of celiac disease could be identified in this group.
Thus how we are born and where we live make a big impact on the likelihood of developing these GI disorders.
- -Gut 2011; 60: 49-54. n=577,627 Danish children. Use of antibiotics associated with increase risk of Crohn’s disease (but not UC), especially at younger ages (3-11month of age, & 2-3yrs of age). Each course increased risk by 18%. In children with >7 courses, relative risk was 7.3. especially penicillins.
- -NEJM 2011; 364: 701, 769. Living on a farm decreases risk of childhood asthma.
- -Nature 2011; 476: 393. ‘Stop killing beneficial bacteria.’ For example, killing H pylori likely increases risk of esophageal adenocarcinoma
- -Gastroenterology 2011; 141: 28, 208. GM-CSF receptor (CD116) defective expression & function in 85% of IBD pts. n=52.
- -Gastroenterology 2010; 139: 1816, 1844. Microbiome & affect on IBD vs mucosal homeostasis
- -J Pediatr 2010; 157: 240. Microbiota in pediatric IBD -increased E coli and decreased F praunsitzil in IBD pts.
- -J Pediatr 2009; 155: 781. early child care exposures lessens risk for asthma.
- -IBD 2008; 14: 575. Role of E coli in Crohn’s
- -Lab Invest 2007; 87: 1042-1054. Role of E coli in Crohn’s
- -Pediatrics 2007; 120: 354. Crohn’s less common after repeated exposure to farm animals in 1st year of life.
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