Five hundred and sixty-one studies with 770 study arms were included in the review with 39,614 participants according to the intention to treat (ITT) analysis and 16,947 participants according to the per protocol (PP) analysis. A total of 3,848 patients were classified as 'all-patients-treated' and were not included in the review.
Of the 770 study arms, 348 were published as full papers and 422 as abstracts only. A total of 369 were randomised study arms, 71 were double-blind, 39 were single-blind, and 660 were open-labelled studies.
Mean eradication rates for bismuth based triple, proton pump inhibitor triple, quadruple and ranitidine bismuth citrate combination therapies vary from 65 to 92%. In the case of nitroimidazole resistance, a drop in efficacy of up to 50% was found for bismuth-based triple and proton pump inhibitor-based triple therapies.
For quadruple therapy, a significant difference in efficacy was found in the equal-effects analysis, however, this could not be confirmed in the random-effects analysis. In the case of clarithromycin resistance, a mean drop in efficacy of 56% was found for one- and two-week clarithromycin containing proton pump inhibitor-triple therapies and of 58% for two-week ranitidine bismuth citrate combined with clarithromycin therapies.
For ranitidine bismuth citrate combined with clarithromycin and nitroimidazole, no difference in efficacy was found in the case of nitroimidazole or clarithromycin resistance, but data are still scarce.