This article is more than 5 years old. Information may no longer be current.
New Study Supports Hygiene Hypothesis in IBD, Shows Ethnicity Influences Risk
Click Here to Manage Email Alerts
A number of factors related to reduced environmental hygiene are associated with a protective effect against developing inflammatory bowel disease, according to the results of a meta-analysis that appear to support the hygiene hypothesis. However, ethnicity appears to heavily influence these associations.
“We demonstrate a robust inverse association between exposure to pets, farm animals, sharing of bedrooms, number of siblings, and risk of IBD,” Aurada Cholapranee, MD, of Montefiore Medical Center, New York, and Ashwin N. Ananthakrishnan, MD, MPH, of Harvard Medical School and Massachusetts General Hospital, wrote. “Importantly, for some exposures, namely, access to toilets or hot water, a statistically significant effect was seen only in non-white populations, whereas for others such as exposure to farm animals, a statistically stronger effect was seen among non-whites.”
Ashwin N. Ananthakrishnan
To examine the relationship between environmental hygiene and IBD risk, Cholapranee and Ananthakrishnan reviewed relevant literature published up to September 2015, and included in their meta-analysis 29 studies that evaluated contact with pets and farm animals, number of siblings, childhood bedroom sharing, and access to a personal toilet and hot water. They further stratified their analysis by ethnicity.
IBD risk was inversely associated with having a dog or cat (OR = 0.76; 95% CI, 0.63-0.88) and having contact with farm animals (OR = 0.45; 95% CI, 0.31-0.6). The association with pets was similar between white and non-white cohorts, but the association with farm animals was stronger in non-whites (OR = 0.27; 95% CI, 0.02-0.53) compared with whites (OR = 0.55; 95% CI, 0.45-0.65; P = .028).
Among both whites and non-whites, Crohn’s disease risk was inversely associated with sharing a home in childhood (OR = 0.49; 95% CI, 0.25-0.75) and IBD risk was inversely associated with sharing a bedroom in childhood (OR = 0.66; 95% CI, 0.46-0.87).
Among non-whites only, the risk for developing ulcerative colitis was inversely associated with having access to a toilet (OR = 0.71; 95% CI, 0.56-0.85) and hot water (OR = 0.67; 95% CI, 0.44-0.89).
Finally, risk for Crohn’s disease was inversely associated with having more than two siblings in both whites and non-whites (OR = 0.93; 95% CI, 0.88-0.98).
These apparent differences in susceptibility based on ethnicity “may reflect an effect modification by ethnicity of origin but could also represent differences in socioeconomic factors or prevailing competing environmental influences between the different regions,” the researchers concluded, adding that further studies of these associations and their underlying mechanisms are needed. – by Adam Leitenberger
Disclosures: Ananthakrishnan reports he has served on scientific advisory boards for AbbVie, Cubist and Exact Sciences.
Click Here to Manage Email Alerts