[Serological Changes after Equivocal Helicobacter pylori-serology Test Findings Dependent on Gastric Secreting Ability]

Background/aims The serum anti-Helicobacter pylori (H. pylori) immunoglobulin G (IgG) and serum pepsinogen (PG) assays are widely used to screen for gastric cancer. An equivocal serology test finding indicates IgG titer between the positive and negative test findings. This study aims to evaluate the long-term follow-up result after an equivocal test finding on the serum anti-H. pylori IgG assay. Methods Koreans aged 18 years or older with an equivocal serum anti-H. pylori IgG assay finding were included. Subjects were excluded if they did not undergo H. pylori serology test, serum PG assay, and upper gastrointestinal (UGI) endoscopy on the same day at our center. The annual test findings were followed-up using the same methods. Results Of the 7,178 subjects who underwent the serum assays and UGI endoscopy on the same day, 274 (3.8%) subjects showed an equivocal H. pylori serology test finding. Of the 98 subjects who were followed-up, 58 (59.2%) showed seropositive finding at the mean follow-up period of 30.6±12.4 months. Subjects with seroconversion showed a higher initial serum PG I (p=0.023) and PG II (p=0.036) levels than those without seroconversion. Conclusions An equivocal H. pylori serology test finding was not rare (3.8%) in Korean adults, and 60% of equivocal subjects showed seroconversion within 3 years. Higher seroconversion rates in subjects with high PG I and PG II levels suggest that intact gastric secreting ability plays a role in the survival of H. pylori. Therefore, equivocal subjects with increased serum PG levels should be considered as potential seropositive subjects.