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Background: As a first-line therapy for Helicobacter pylori, dual therapy with vonoprazan and amoxicillin (VA-dual) provides an eradication rate similar to that of vonoprazan-based triple therapy. As the factors associated with the eradication rate of H. pylori with VA-dual are unknown,we investigated them in this study., Materials and Methods: Overall, 163 patients diagnosed with H. pylori infection received VA-dual (vonoprazan 20 mg twice daily and amoxicillin 750 mg twice daily for 7 d). The association between successful H. pylori eradication and the following patient clinical factors was analyzed: sex, age, height, weight, body surface area (BSA), body mass index (BMI), history of early gastric carcinoma and peptic ulcer, comorbidity of cirrhosis, alcohol consumption habit, smoking habit, common use of proton pump inhibitors, and concomitant use of drugs that are substratesof cytochrome P450 (CYP) 3A4. The association between post-eradication adverse events and clinical factors was analyzed retrospectively., Results: Successful H. pylori eradication was associated with a lower BSA (eradication rate: 90.8% in patients with BSA <1.723 vs. 79.6% in those with BSA ≥1.723; p = 0.045). The incidence of adverse events was higher in women than in men (adverse events: 40.0% in women vs. 19.4% in men; p = 0.004)., Conclusions: Successful H. pylori eradication with VA-dual was associated with the small body size of patients. This therapy may have to be adjusted per body size., (© 2021 John Wiley & Sons Ltd.)

Eradication of Helicobacter pylori (Hp) is necessary for preventing peptic ulcers and stomach cancer. The potassium-competitive acid blocker vonoprazan is a gastric acid secretion inhibitor that improves the success rate of Hp eradication through its immediate and persistent inhibition of acid excretion. In Japan, first-line treatment involves a regimen in which vonoprazan is combined with amoxicillin and clarithromycin, while second-line treatment involves vonoprazan combined with amoxicillin and metronidazole. However, in contrast to the vonoprazan-based first-line therapy, no studies have investigated the factors influencing the success of vonoprazan-based second-line therapy. In this study, we therefore aimed to investigate factors related to the success of vonoprazan-based second-line therapy. We analyzed the association between the success of Hp eradication and patient factors including metronidazole/amoxicillin minimal inhibitory concentrations (MICs). MICs were measured using the Hp isolated from each patient. A receiver operating characteristic (ROC) analysis was conducted to examine continuous variables and eradication success. We reviewed the records of 33 patients (age: 34-79 years, male/female: 22/11, and body mass index (BMI): 16.1-28.8 kg/m 2 ) who underwent vonoprazan-based second-line therapy after failure of first-line therapy at seven Japanese facilities between October 2018 and June 2019. The eradication success rate was 81.8% (27/33). ROC analysis revealed an area under the curve and BMI cutoff value of 0.796 and 23.8 kg/m 2 , respectively. The eradication success rate was higher in patients with high BMI than in those with low BMI (p = 0.007). Our findings indicate that higher BMI is correlated with the success of vonoprazan-based second-line therapy.

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 13 C urea breath test and the findings of gastric mucosal atrophy by performing an upper gastrointestinal endoscopy. A positive 13 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 13 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.