Four randomised controlled trials (RCTs) were included: 2 placebo-controlled RCTs (N=333) published in the US, and 2 further RCTs (N=327) published elsewhere.
The rate of HP infection in patients on entry was 68% for the US studies, versus 94%% for the non-US studies.
US studies.
The ulcer healing rates at 4 weeks were: for the RBC (400 mg) and clarithromycin combination, 71 and 82%, (p<0.001 versus the placebo groups); RBC, 66 and 74%; for clarithromycin, 49 and 73%; and for placebo, 15 and 52%. HP eradication 4 weeks after therapy was: for the RBC (400 mg) and clarithromycin combination, 86 and 82% (p<0.01 versus the other 3 groups); for RBC, 0 and 0%; for clarithromycin, 24 and 36%; and for placebo, 0 and 0%.
Ulcer recurrence 24 weeks after healing (1 RCT, N=117) was: for the RBC (400 mg) and clarithromycin combination, 30%; for RBC, 77%; for clarithromycin, 36%; and for placebo, 80%.
Adverse effects: the discontinuation rate due to adverse effects ranged from 2 to 6% (1 RCT, N=204), with the highest rate occurring in the group receiving the double placebo.
Non-US studies.
The ulcer healing rates at 4 weeks were: for the RBC (400 mg) and clarithromycin combination, 88 and 89%; for the RBC (800 mg) and clarithromycin combination, 88 and 93%; and for RBC, 71 and 83%.
HP eradication 4 weeks after therapy was: for the RBC (400 mg) and clarithromycin combination, 82 and 94% (p<0.001 versus monotherapy); for the RBC (800 mg) and clarithromycin combination, 74 and 84% (p<0.001 versus monotherapy); and for RBC, 0 and 2%.
The occurrence of adverse reactions was: for the RBC (400 mg) and clarithromycin combination, 31 and 28%; for the RBC (800 mg) and clarithromycin combination, 35 and 25%; and for RBC, 23 and 29%.
Ulcer recurrence 24 weeks after healing (1 RCT, N unknown) was: for the RBC (400 mg) and clarithromycin combination, 6%; for the RBC (800 mg) and clarithromycin combination, 9%; and for RBC, 40%.
No details were provided in the original studies as to how the adverse reactions were classified, or how many were serious or resulted in discontinuation of the therapy.