HP-/IgG- N=10 (3.6%) HP+/IgG+ N=240 (85.7%) HP-/IgG+ N=4 (1.4%) HP+/IgG- N=26 (9.3%) P-value Male/Female 8/2 (80.0%/20.0%) 141/99 (58.8%/41.2%) 3/1 (75.0%/25.0%) 18/8 (69.2%/30.8%)   Age (years) 63.4 ± 8.6 56.5 ± 11.0 63.3 ± 16.6 66.1 ± 13.8 <0.001 Eradication history (none) 5 (50.0%) 178 (74.2%) 1 (25.0%) 6 (23.1%)   RUT (positive) 0 234 (97.5%) 0 16 (64.0%) 　 PCR (positive) 0 230 (95.8%) 0 24 (92.3%) 　 Culture (positive) 0 193 (80.4%) 0 2 (7.7%) 　 ABC classification A/B/C/D (n/n/n/n) 10/0/0/0 0/113/127/0 0/3/1/0 11/0/0/15

Table 2: Demographic clinical characteristics of each group. Values are presented as mean ± standard deviation Hp-/IgG-, uninfected with H. pylori and negative for anti-H. pylori IgG antibody; Hp+/IgG+, infected with H. pylori and positive for anti-H. pylori IgG antibody; Hp-/IgG+, uninfected with H. pylori but positive for anti-H. pylori IgG antibody; Hp+/IgG-, infected with H. pylori but negative for anti-H. pylori IgG antibody.