The prevalence of H. pylori infection at entry to the study was 82.2% [95% confidence interval (CI) 78-87%]. The overall eradication rate 6 weeks after treatment was 49.1% (95% CI 42.6-55.6%) by intention-to-treat analysis, and 60% (95% CI 53-67%) by per-protocol analysis. Recurrence rate of H. pylori infection at 1 year was 34% (95% CI 14-45%) and the only predictor of recurrence was an excess delta C-UBT value less than 3.5 per million but equal to or greater than 2.5 per million at 6 weeks after treatment (odds ratio 2.28; 95% CI 1.17-4.44; P = 0.028).