Causes of Atrophic Gastritis
Atrophic gastritis is caused primarily by chronic Helicobacter pylori infection (the dominant etiology) or autoimmunity, with H. pylori being responsible for the vast majority of cases. 1
Primary Etiologies
Helicobacter pylori Infection (Most Common)
- H. pylori is the most important causative factor, present in 71-95% of all gastric cancer cases that develop from atrophic gastritis 2
- The infection causes persistent active gastritis that progressively leads to atrophic gastritis, intestinal metaplasia, and potentially gastric adenocarcinoma 2
- Patients with H. pylori infection have a 5-fold increased risk of developing atrophic gastritis (rate ratio 5.0,95% CI 3.1-8.3) compared to uninfected individuals 1
- Among H. pylori-uninfected individuals, atrophic gastritis incidence is very low (<1% annually), confirming the strong causal relationship 1
- H. pylori-associated atrophic gastritis is the dominant form, accounting for the majority of the estimated 15% prevalence in US populations 1, 3
Autoimmune Gastritis (Less Common)
- Autoimmune gastritis is significantly less common, with an estimated prevalence of only 0.5-2% compared to up to 15% for all forms of atrophic gastritis 1, 3
- This form is characterized by autoantibodies against parietal cells and intrinsic factor, leading to corpus-predominant atrophy 2
- The prevalence increases with age and is more common in women 1, 3
- Autoimmune gastritis is strongly associated with other autoimmune diseases, particularly autoimmune thyroid disease (Hashimoto's thyroiditis), with up to one-third of patients with autoimmune thyroid disease having autoimmune gastritis 2, 4
Additional Risk Factors for Non-Autoimmune Atrophic Gastritis
Beyond H. pylori infection, several factors contribute to the development of atrophic gastritis:
- Advanced age is an independent risk factor 1, 3
- Tobacco use increases risk 1, 3
- High-salt diet contributes to gastric mucosal damage 1, 3
- Chronic bile acid reflux may play a role, though evidence is less definitive 1, 3
Population-Specific Considerations
- Non-White racial/ethnic minority groups and early-generation immigrants from high-risk countries have higher rates of atrophic gastritis due to increased H. pylori prevalence 1, 3
- In contrast, racial and ethnic variation is not prominent in autoimmune gastritis 3
Clinical Pitfalls to Avoid
- Do not overlook atrophic gastritis in patients with unexplained iron or vitamin B12 deficiency, as this may be the only presenting manifestation, especially in corpus-predominant disease 1, 2
- Screen patients with autoimmune thyroid disease for atrophic gastritis, given the strong association (up to one-third prevalence) 4
- Recognize that atrophic gastritis is often asymptomatic and underdiagnosed due to inconsistent histopathologic reporting 1, 3
- All individuals with atrophic gastritis should be assessed for H. pylori infection, as this is the treatable dominant cause 1