Natural history of autoimmune atrophic gastritis: a prospective, single centre, long-term experience

Background: Autoimmune atrophic gastritis (AAG) is an immune-mediated disorder characterised by destruction of gastric oxyntic mucosa. Aims: To explore gastric histopathological evolution in a cohort of AAG patients over a prolonged follow-up. Methods: Single centre prospective study enrolling consecutive patients with histologically confirmed AAG between 2000 and 2018. All AAG patients undergoing endoscopic follow-up every 1-3 years were classified as having stages 1, 2 or 3 according to atrophy severity (mild, moderate and severe). AAG patients with either glandular or neuroendocrine dysplasia/neoplasia were classified as having stage 4. Disease stage progression, and changes in serum anti-parietal cell antibody (PCA), chromogranin A and gastrin-17 were assessed. Results: In total, 282 AAG patients (mean age 60.3 years; F:M ratio 2.4:1; median follow-up 3 years, interquartile range 1-7) were enrolled. All patients with stages 1 or 2 progressed to stage 2 or 3 over time with a steady trend (P =.243) and regression from a severe to a milder stage was never noticed. Disease progression of patients with stages 1 or 2 occurred within the first 3 years. PCA positivity rate did not change over time. Stage 3 patients had higher gastrin-17 levels compared to patients with stages 1 and 2 (median 606 vs 295 pg/mL; P <.001). In stage 3, the hazard ratio for the risk of developing stage 4 was 6.6 (95% CI 1.5-29; P =.001). Conclusions: AAG is a steadily progressive disease, in which stages 1 and 2 always progress to stage 3. The risk of developing a complicated disease stage is greater in patients with more severe gastric lesions.