Inflammatory bowel disease (IBD) and microscopic colitis are characterized by different geographical distributions across the USA.
Dr Sonnenberg and colleagues from Oregon, USA performed a cross-sectional study and utilized demographic and socio-economic information associated with individual ZIP codes to further delineate the epidemiological characteristics of the 2 diseases.
A total of 813,057 patients who underwent colonoscopy between 2008 and 2014 were extracted from an electronic database of histopathology reports.
The prevalence of patients with IBD or microscopic colitis was expressed as percentage of the population associated with specific demographic, and socio-economic characteristics.
|Ethnic variations were more pronounced in microscopic colitis than IBD|
Both diseases were more common among subjects from ZIP codes with predominantly White residents and less common among subjects from ZIP codes with predominantly non-White residents such as Black, Hispanic and Asian.
The researchers found that these ethnic variations were more pronounced in microscopic colitis than IBD.
The team observed that markers of affluence, such as average residential house value and annual income, were positively associated with IBD and negatively with microscopic colitis.
The research team noted that the prevalence of both diseases was positively correlated with tertiary education.
Dr Sonnenberg's team concludes, "The occurrence of both IBD and microscopic colitis is influenced by environmental risk factors."
"The differences in the demographic, ethnic and socio-economic distributions of the 2 diseases suggest that different sets of risk factors affect the 2 diseases and that their etiology is unrelated."