Analyses of the association between <i>Helicobacter pylori</i> antibody titre and pathogenicity before and after eradication: results of the Kyushu and Okinawa population study, a retrospective observational cohort study.

Abstract

To assess the utility of <i>Helicobacter pylori</i> antibody testing, we evaluated the correlation between the <i>H. pylori</i> antibody titre and <i>H. pylori</i>-associated pathogenicity and the changes in antibody titre after <i>H. pylori</i> eradication therapy. A retrospective observational cohort study. From 2004 to 2016, medical check-ups were performed in different regions of Japan. In total, 324 subjects infected with <i>H. pylori</i> who received <i>H. pylori</i> eradication therapy were enrolled; <i>H. pylori</i> was eradicated in 266 of these subjects. We examined the associations between <i>H. pylori</i> antibody titre with pepsinogen and the presence or absence of <i>H. pylori</i>-associated pathogenic proteins, such as cytotoxin-associated gene A and vacuolating cytotoxin gene A, at baseline and after <i>H. pylori</i> eradication therapy. The <i>H.pylori</i> antibody titre showed a positive correlation with pepsinogen II and a negative correlation with the pepsinogen I/II ratio. Moreover, the <i>H.pylori</i> antibody titre significantly correlated with the positive rates of <i>H. pylori</i>-associated pathogenic protein before eradication therapy. Antibody titres decreased after eradication, the pepsinogen I/II ratio increased and the <i>H. pylori</i>-associated pathogenic protein-positive rate decreased in patients with successful eradication. The determination of eradication using the decline in antibody titre 6 months after eradication therapy was useful (area under the receiver operating characteristic curve: 0.98). Our data indicate that the <i>H. pylori</i> antibody titre may represent the degree of pathogenicity. The <i>H. pylori</i> antibody titre was associated with attenuation of pathogenicity in patients with <i>H. pylori</i> eradication, indicating the clinical utility of <i>H. pylori</i> antibody testing.