Sixty-three clinical trials and 3 overviews were included.
The validity of the primary studies was variable; the mean overall score was 5.5.
Overt bleeding: compared with placebo or no therapy, histamine-2-receptor antagonists reduced overt bleeding (common OR 0.29, 95% confidence interval, CI: 0.17, 0.45), as did antacids (OR 0.40, 95% CI: 0.20, 0.79). Histamine-2-receptor antagonists were more effective in reducing overt bleeding than antacids (OR 0.56, 95% CI: 0.33, 0.97).
Clinically-important bleeding: compared with no therapy, histamine-2-receptor antagonists reduced the incidence of clinically-important bleeding (OR 0.35, 95% CI: 0.15, 0.76), as did antacids (OR 0.35, 95% CI: 0.08, 1.33).
Pneumonia: sucralfate reduced the incidence of pneumonia when compared with two gastric pH-altering agents (OR 0.50, 95% CI: 0.21, 0.79).
Mortality: sucralfate was associated with a lower mortality rate than antacid therapy (OR 0.70, 95% CI: 0.52, 0.94).