A Retrospective Study on Clinical Characteristics of Autoimmune Gastritis With and Without Anemia

Background: Autoimmune gastritis (AIG) is an immune-mediated chronic atrophic gastritis, and anemia is common in AIG. This study aims to investigate the clinical characteristics of AIG patients with and without anemia. Methods: This was a single-center retrospective study. The diagnosis of AIG was based on endoscopic or pathologic findings combined with antiparietal cell antibody (PCA) and anti-intrinsic factor antibody (IFA) results. Anemia was defined as hemoglobin levels <110 g/L for females or 120 g/L for males. Results: This study included 117 AIG patients. The median age was 53.6±10.5 years old, and 72.6% were female. Anemia was present in 39.3% patients, with 17.9% iron deficiency anemia (IDA) and 21.4% pernicious anemia (PA). AIG patients with anemia had a higher positive rate of IFA (34.8% vs. 18.3%, P =0.044) and a lower level of pepsinogen I (PG-I) [5.0 (3.3 to 10.4) vs. 8.0 (4.1 to 18.9) ng/mL, P =0.033]. However, no significant differences were observed in the age, sex, PCA positivity, gastrin levels, Helicobacter pylori ( H. pylori ) infection status or the concomitant diseases between patients with and without anemia. Compared with PA patients, IDA patients had a higher incidence of H. pylori infection (66.7% vs. 28.0%, P =0.009), as well as the levels of PG-I ( P =0.001), PG-II ( P =0.016) and PG-I/II ratio ( P =0.007). Univariate and multivariate analyses revealed that IFA positivity (odds ratio=2.379, P =0.047) was a significant risk factor for anemia in AIG patients. Conclusions: AIG patients with IFA positivity are more prone to anemia, and IDA maybe associated with H. pylori infection.