Rates of venous thrombosis after general surgery: combined results of randomised clinical trials.

Despite evidence that prophylaxis against deep-vein thrombosis (DVT) is effective, a large proportion of general surgical patients receive no prophylaxis. To determine the extent to which various prophylactic methods reduce the incidence of postoperative DVT, data from randomised controlled trials of these methods were combined by means of meta-analysis. The rates of DVT diagnosed by the fibrinogen uptake test were: control/no therapy 27.0% (95% confidence limits 21.9%, 32.1%); heparin 9.6% (7.2%, 11.9%); gradient compression stockings 11.1% (5.3%, 16.8%); intermittent pneumatic compression 17.6% (6.1%, 29.1%); heparin plus stockings 6.3% (0%, 17.6%); heparin plus dihydroergotamine 9.9% (6.2%, 13.6%); and stockings plus intermittent pneumatic compression 4.5% (1.1%, 8.0%). These results confirm the value of prophylaxis to reduce the incidence of DVT and suggest that combined treatments may be most effective.