E plate

Baseline covariates of the present study included age, birth year, gender, body mass index, blood pressure, laboratory blood data such as total cholesterol, high-density lipoprotein cholesterol, aspartate aminotransferase, history of cancer, history of medication for HP, and urine anti-HP antibody status determined using an immunochromatography kit (RAPIRAN, Otsuka Pharmaceutical, Tokushima, Japan) [27 (link)–29 (link)]. For the baseline laboratory blood data analysis, peripheral blood was drawn in the morning using three 7-ml vacuum tubes after overnight fasting. Details of the procedures were described in our previous study [30 (link)]. The RAPIRAN is a de facto standard kit for anti-HP antibody detection in urine [31 (link)]. It has been reported that the sensitivity, specificity, and consistency of the RAPIRAN kit against an independent serum enzyme immunoassay E-plate (Eiken, Tokyo, Japan) was 86.2%, 93.7%, and 90.1%, respectively [31 (link),32 (link)]. Moreover, an apparent birth-year effect to HP infection rate can be assessed in order to evaluate if the RAPIRAN kit has introduced a bias for anti-HP antibody detection in the current cohort.

For comparison of the diagnosis of H. pylori infection, a combined serum test of anti-H. pylori antibody and pepsinogen (PG) I and II, the ABC method [12 (link)–14 (link)], was used. According to serum antibody to H. pylori and pepsinogen I and II values, H. pylori infection status and grade of gastric atrophy were classified into Group A–D: A, H. pylori antibody (−) and gastric atrophy (−); B, antibody (+) but atrophy (−); C, antibody (+) and atrophy (+); D, antibody (−) and atrophy (+). As reported [6 (link)], the serum antibody to H. pylori was measured with an enzyme immunoassay method (E-plate, Eiken Chemical, Tokyo, Japan), and a cutoff value of ≥ 3 U/mL was used to reduce false-negative results [15 (link)]. PGI and II were measured with the chemiluminescent enzyme immunoassay method (Fujirebio, Tokyo, Japan), and PG I of ≤ 70 ng/mL and PG I/II ratio of ≤ 3.0 were considered positive for PG test [16 (link)].

Serum anti-HP IgG antibody titers were measured by enzyme-linked immunosorbent assay (ELISA) using the E-Plate Eiken or E-Plate II Eiken (Eiken Chemical Co., Ltd., Tokyo, Japan), following the manufacturer's instructions. Values greater than 10 U/mL were considered to indicate HP infection.

To fully evaluate the degree of changes in gastrin and pepsinogen caused by acid inhibitors, the values of these serum markers before and after administration were compared. Additionally, to examine the changes in G7 levels before and after administration, 10 cases from each group, the PPI group and PCAB group, were randomly selected for analysis. Fasting sera were collected on the day of the ESD and 4 weeks later and stored at -20°C until analysis. The levels of serum gastrin (Gastrin RIA Kit II; Dainabot, Tokyo, Japan), G17 (Gastrin-17 Advanced ELISA, Biohit, Finland), and PG (LZ test; Eiken, Tokyo, Japan) and the anti-H. pylori antibody titers (E-plate; Eiken, Tokyo, Japan) were evaluated [15 (link)].

Serum samples were collected after one night of fasting and stored at −20°C. The titer of serum IgG antibody to H. pylori was measured by E-plate (Eiken, Tokyo, Japan) (17 (link)). Stool samples were collected and stored at −80°C. Stool samples were tested for H. pylori antigen by using Testmate EIA (Wakamoto and Kyowa Medex, Tokyo, Japan) (18 (link)). H. pylori status was defined as positive when the stool antigen test was positive and serum antibody titer ≥10 U/mL, and as negative when the stool antigen test was negative and serum antibody titer <3 U/mL.