RESUMEN
BACKGROUND AND AIMS: Resistance rates of Helicobacter pylori to clarithromycin, metronidazole, and quinolone are over 30% in South Korea. The aim of this prospective study was to evaluate the ultimate eradication rate of H. pylori after first, second, or third-line therapy in Korea. METHODS: A cohort of 2202 patients with H. pylori was treated with proton pump inhibitor (PPI)-based triple therapy for seven days. In case of treatment failure or recurrence, moxifloxacin-based triple therapy (MA) or bismuth-based quadruple therapy (QUAD) was randomly given. When the second-line treatment failed or H. pylori recurred, the unused MA or QUAD was used as a third-line treatment. RESULTS: Eighty-six patients had recurrence at least once during consecutive lines of treatments. Among 2116 patients (intention-to-treat [ITT]) without recurrence, 1644 (77.7%, per-protocol [PP]) completely followed our treatment flow. The ITT and PP rates of first-line treatment were 69.8% and 89.3%. After second line, they reached 78.4% (ITT) and 98.4% (PP). The "final" eradication rate up to third line treatment were 80.0% (1692/2116) and 99.8% (1641/1644), respectively. Resistance to clarithromycin showed significantly lower eradication rate (OR 0.358, P < 0.001) than those with susceptible strains in multivariate analysis. However in PP analysis, there was no significant difference in ultimate success rate regarding resistance pattern. CONCLUSION: Final success rate of PP was high, 99.8% in Korea in spite of high antibiotic resistance rates. However, high rate of refusal of further treatment and follow-up loss made ITT eradication rate low. Proper strategy to improve the treatment adherence is needed.