Eosinophilic esophagitis is an increasingly prevalent chronic disease arising from an allergy/immune-mediated process.
Generally, the risk of atopic disease differs in rural and urban environments.
The relationship between population density and eosinophilic esophagitis is unknown.
Dr Evan Dellon and colleagues from North Carolina, USA assessed the relationship between eosinophilic esophagitis and population density.
The researchers conducted a cross-sectional, case–control study of patients with esophageal biopsies in a US national pathology database between 2009 and 2012 to assess the relationship between population density and eosinophilic esophagitis.
Using geographic information systems, the population density (individuals per square mile) was determined for each patient zip code.
|The odds of having esophageal eosinophilia increased with decreasing population density|
|American Journal of Gastroenterology|
The odds of esophageal eosinophilia and eosinophilic esophagitis were estimated for each quintile of population density and adjusted for potential confounders.
Sensitivity analyses were conducted with varying case definitions, and to evaluate the potential for bias from endoscopy volume and patient factors.
The researchers found that of 292,621 unique patients in the source population, 89,754 had normal esophageal biopsies, and 14,381 had esophageal eosinophilia with =15 eosinophils per high-power field.
The team noted that the odds of having esophageal eosinophilia increased with decreasing population density.
The research team observed that compared with those in the highest quintile of population density, odds of having esophageal eosinophilia were significantly higher among those in the lowest quintile of population density.
A similar dose–response trend was observed across case definitions with increased odds of eosinophilic esophagitis in the lowest population density quintile.
Dr Dellon's team concludes, "Population density is strongly and inversely associated with esophageal eosinophilia and eosinophilic esophagitis."
"This association is robust to varying case definitions and adjustment factors."
"Environmental exposures that are more prominent in rural areas may be relevant to the pathogenesis of eosinophilic esophagitis."