[Infection status of Helicobacter pylori with antibody values of 3.0U/mL or more and less than 10.0U/mL in the LZ test "Eiken" H. pylori antibody].

The LZ test "Eiken" for H. pylori antibody (LZ test) was examined. In patients with an antibody titer of ≥3.0U/mL and <10.0U/mL among 698 patients who underwent breath tests, the status of H. pylori infection was assessed from the results of the C urea breath test and the findings of gastric mucosal atrophy by performing an upper gastrointestinal endoscopy. A positive C urea breath test was observed in 22.3% of these patients (156/698, 95% confidence interval 19.4-25.6%), and gastric mucosal atrophy of C-2 or greater was observed in 39.7%. We presumed that 156 (22.3%) patients had present H. pylori infections, 141 (20.2%) patients had experienced a previous infection, and 401 (57.5%) patients were uninfected. The infection rate of H. pylori (current infection+previous infection) was treated as a so-called "risk of gastric cancer" and was 42.6% (297/698, 95% confidence interval 38.9-46.3%). In the LZ test, the concept of a negative high value should be understood. A receiver operating characteristic curve plotted depending on whether the C urea breath test was positive or not gave a positive cutoff value of 5.6U/mL;values greater than the cutoff value were taken as indicative of the need to investigate the status of H. pylori infection. Even without gastric mucosal atrophy, 2.0% of these patients had a positive breath test. For gastritis localized in the antrum (C-1), 17.8% of the patients had positive breath test results.