Corpus-predominant gastritis as a risk factor for false-negative super(13)C-urea breath test results

Background: Urea breath test sensitivity seems affected by increased intragastric acidity during therapy with antisecretory drugs. Intragastric pH is increased in patients with corpus gastritis with/without atrophy. Aim: To test the hypothesis that urea breath test results may also be affected by this gastritis phenotype. Methods: 123 untreated patients underwent gastroscopy plus biopsies and intragastric pH measurement. The study included 82 endoscopically proven Helicobacter pylori-positive patients who were offered urea breath test with an acidic meal. Histological findings, urea breath test results and intragastric pH were compared in 66 of the subjects. Results: 21 of 66 (31.8%) patients had a false-negative urea breath test. In these patients corpus-predominant gastritis (85.7% vs. 37.7%; P = 0.0004) and fundic atrophy (66.6% vs. 17.7%; P = 0.0001) were more frequent than in patients with true-positive urea breath test. Intragastric pH was higher in false-negative patients (mean 6.3 vs. 4.4; P = 0.001). In a multivariate analysis, the only risk factor for a false-negative urea breath test was the presence of corpus-predominant gastritis (OR = 5.6; 95% CI: 1.1-27). There was a negative correlation between the intragastric pH and the delta over baseline values (r = -0.378; P = 0.0023). Conclusions: Our results support the hypothesis that the pattern of gastritis can affect the sensitivity of urea breath test, and suggest that patients with corpus-predominant gastritis have a high risk of false-negative urea breath test results.