Gastric Mucosa Assessment via Biomarkers

Fasting blood samples were collected from participants, and the serum samples were stored at − 20 °C until use. Serum PG I and PG II levels were measured by radioimmunoassay (Abbott, Tokyo, Japan) from 1990 to 1999, chemiluminescent immunoassay (Abbott) from 1999 to 2001, enzyme immunoassay (E-plate test; Eiken, Tokyo, Japan) from 2001 to 2003, and latex agglutination test (L-Z test; Eiken) from 2003 to 2014. Patients with PG I levels > 70 ng/mL or PG I/PG II levels > 3 ng/mL were considered to have high PG levels [13 (link)]. Serum Hp-Ab titers were evaluated using an enzyme-linked immunosorbent assay (E-plate; Eiken). The cut-off value was set to 3 U/mL [24 (link)]. Using the definition of the ABC method, we classified patients with high PG levels and negative Hp-Ab, high PG levels and positive Hp-Ab, low PG levels and positive Hp-Ab and low PG levels and negative Hp-Ab, into groups A, B, C and D, respectively [13 (link)].