Eight RCTs (n=454) were included. Six studies (n=343) were included in the meta-analysis.
Five studies scored a maximum of 5 points for methodological quality and three scored 3 points. There was some evidence of publication bias.
There were no statistically significant differences between heparin supplementation and conventional therapy (OR 0.78, 95% CI: 0.50, 1.21) in response rates. Sensitivity analyses showed similar effects. There were no significant differences for clinical, endoscopic, histologic or serologic evaluations between either heparin or conventional groups.
Treatment with UFH was significantly more effective than conventional therapy (OR 0.26, 95% CI: 0.07, 0.93). There was no significant difference between groups receiving LMWH compared with conventional therapy (OR 0.92, 95% CI: 0.57, 1.47). There were also no significant differences between heparin and placebo (3 studies) or between heparin and conventional therapy (3 studies).
There was no evidence of significant heterogeneity in any of these analyses.
There were no significant differences between heparin and conventional treatment for clinical score (6 out of 7 studies), endoscopic score (6 out of 7 studies), histologic score (all 4 studies) and C-reactive protein (all 3 studies). One of the 2 studies of erythrocyte sedimentation reported a significant reduction, but only in the conventional treatment group and not the heparin group.
There were no significant differences in adverse events between groups in any trials. Serious adverse events included rectal bleeding and nausea.