Community-Based Research on H.pylori Infection in the Canadian Arctic: Findings Show a High Prevalence of Severe Gastritis

INTRODUCTION: Residents of Arctic Aboriginal communities have a high prevalence of H.pylori infection. In response to community concerns about cancer risk from this infection, the CANHelp Working Group established community projects to investigate the disease burden and improve disease control strategies. We present preliminary analysis of the distribution and determinants of gastritis severity in Aklavik, Northwest Territories and Old Crow, Yukon, where community-wide screening estimated H.pylori prevalence at 58% (192/332) and 68% (126/186), respectively.

METHODS: Consenting participants underwent upper endoscopy with gastric biopsy in 2008 in Aklavik and 2011 in Old Crow. For each participant, 5 biopsies were assessed for H pylori and gastritis severity by a single pathologist using the Sydney classification. Data on potential risk factors came from structured interviews. ORs and 95% CIs for the effect of exposures of interest on severe gastritis among H.pylori-positive participants were estimated by logistic regression.

RESULTS:  In both communities, <10% of H.pylori–positive persons had normal-mild gastritis, so gastritis severity was dichotomized as severe v. mild/moderate. The prevalence of severe gastritis was high (Aklavik, 43%, CI:34%,52%; Old Crow, 65%, CI:51%,77%). As a potential risk factor of community interest, initial analysis focused on the effect of untreated river water consumption on severe gastritis prevalence; the estimated OR was 1.8 (CI: 0.86, 3.8) adjusting for age, ethnicity, educational attainment, alcohol consumption, smoking, NSAID use and community. Given the potential for variation in water quality by community, this effect was also estimated by community (Aklavik, 2.8,CI:1.1,7.2; Old Crow 0.85,CI:0.19,3.9).

CONCLUSIONS: Our results show high frequencies of severe gastritis among individuals with H.pylori infection in two Arctic Canadian communities. Our results show higher prevalence of severe gastritis among participants who consume untreated river water in one of the communities. Further analysis will include data from other Arctic communities to estimate effects of additional dietary factors.