Abstract
Subjects with a high-negative titer (3-9.9 U/ml) of serum anti-Helicobacter pylori (H. pylori) antibody represent a heterogeneous group of currently H. pylori-infected, H. pylori-uninfected, and previously H. pylori-infected cases. We investigated the characteristics of subjects with a high-negative titer during a medical check-up and the utility of H. pylori infection score, the sum of scores of endoscopic findings based on the Kyoto Classification of Gastritis, for diagnosing H. pylori infection. Subjects with (13)C-urea breath test-positive or H. pylori stool antigen test-positive were diagnosed as currently H. pylori-infected. Although around half of subjects with a high-negative titer were after eradication therapy (48.6%), currently H. pylori-infected were considerably confirmed (11.7%). H. pylori infection score showed a high value of area under the receiver operating characteristic curve [0.92; 95% confidence interval (CI), 0.84-1.00] with the most suitable cut-off value of 1.0 (sensitivity: 0.92; specificity: 0.90). Multivariate logistic regression analysis revealed that H. pylori infection score was an independent factor associated with increased prevalence of H. pylori infection (odds ratio, 9.53; 95% CI, 2.64-34.40; p<0.001). Currently H. pylori-infected subjects were considerably included among the subjects with a high-negative titer, and the Kyoto Classification of Gastritis was useful to predict current H. pylori infection.