Introduction: Case control studies suggest an inverse association between Helicobacter pylori (H. pylori) and Crohn's disease (CD). It is possible this could be accounted for by confounders such as antibiotic therapy. Analyzing the geographic distribution of H. pylori and the links with the incidence and prevalence of CD would be an alternative approach to circumvent these confounders.
Methods: The literature was searched for studies published between 1990 and 2016 that reported incidence or prevalence data for CD in random population samples in developed countries (GDP per capita >20,000 USD/year). Corresponding prevalence studies for H. pylori in these same regions were then sought matched to the same time period (±6 years). The association between the incidence and prevalence of CD and H. pylori prevalence rates were assessed before and after adjusting for GDP and life expectancy.
Results: A total of 19 CD prevalence and 22 CD incidence studies from 10 European countries, Japan, USA, and Australia with date-matched H. pylori prevalence data were identified. The mean H. pylori prevalence rate was 43.4% (range 15.5-85%), and the mean rates for incidence and prevalence for CD were 6.9 and 91.0/100,000 respectively. The incidence (r = -0.469, p < 0.03) and prevalence (r = -0.527, p = 0.02) of CD was inversely and significantly associated with prevalence of H. pylori infection.
Conclusions: Our data demonstrate a significant inverse association between geographic distribution of H. pylori and CD. Thus, it is highly unlikely that the findings of previous case control studies were simply due to confounding factors such as concomitant antibiotic use in CD patients.
Keywords: Crohn’s disease; Developed countries; Gastrointestinal infection; H. pylori prevalence; Hygiene hypothesis; Incidence and prevalence.