Dr Eric Benchimol and colleagues from Canada determined the association between inflammatory bowel disease (IBD) and rural/urban household at the time of diagnosis, or within the first 5 years of life.
Population-based cohorts of residents of four Canadian provinces were created using health administrative data.
Rural/urban status was derived from postal codes based on population density and distance to metropolitan areas.
Validated algorithms identified all incident IBD cases from administrative data.
The researchers determined sex-standardized incidence, and incident rate ratios using Poisson regression.
The research team created a birth cohort was created of children in whom full administrative data were available from birth.
|Incidence of IBD per 100,000 was 31 in rural residents|
|American Journal of Gastroenterology|
The researchers calculated IRR for residents who lived continuously in rural/urban households during each of the first 5 years of life.
The team found 6,662 rural residents, and 38,905 urban residents with IBD.
Incidence of IBD per 100,000 was 33 in urban residents, and 31 in rural residents.
The research team observed that the protective association was strongest in children less than 10 years, and 10 to 18 years.
In the birth cohort, comprizing 331 rural and 2,302 urban residents, the team noted that rurality in the first 1–5 years of life was associated with lower risk of IBD.
Dr Benchimol's team concludes, "People living in rural households had lower risk of developing IBD."
"This association is strongest in young children and adolescents, and in children exposed to the rural environment early in life."