Current issues of ACP Journal Club are published in Annals of Internal Medicine


Therapeutics

Postoperative prophylaxis for venous thromboembolism is effective

ACP J Club. 1995 Sept-Oct;123:31. doi:10.7326/ACPJC-1995-123-2-031


Source Citation

Kearon C, Hirsh J. Starting prophylaxis for venous thromboembolism postoperatively. Arch Intern Med. 1995 Feb 27;155:366-72.


Abstract

Objective

To determine the relative safety and efficacy of starting venous thromboembolism (VTE) prophylaxis before and after surgery in patients at risk for VTE.

Data Sources

A MEDLINE search was done (1990 to 1994) using the terms embolism, thrombosis, and prophylaxis; personal reprint files were checked; and the bibliographies of consensus papers, reviews, book chapters, and studies identified from MEDLINE and personal files were reviewed.

Study Selection

Included studies were single- or double-blind randomized trials comparing patients receiving prophylaxis after surgery with 1) an untreated control group, 2) patients receiving another method of prophylaxis, or 3) patients receiving prophylaxis before surgery. The timing of prophylaxis had to be clear, and VTE had to have been diagnosed without knowledge of treatment assignment.

Data Extraction

Rates of VTE and bleeding.

Main Results

12 fully published studies and 1 abstract met the selection criteria. 8 studies compared patients receiving prophylaxis after surgery (4 pharmacologic, 4 nonpharmacologic) with an untreated control group, and 5 were about different methods of prophylaxis and did not have an untreated control group. No studies compared the same method of prophylaxis initiated before and after surgery. All studies but 1 were of patients having elective knee or hip surgery. Of the studies with an untreated control group and postoperative prophylaxis with mechanical devices, 2 showed that intermittent pneumatic compression (IPC) led to a clinically important reduction in the rate of VTE; 1 used IPC of the calf (relative risk [RR], 0.18; 95% CI 0.004 to 1.34) and the other used IPC of the calf and thigh (RR, 0.49; CI, 0.35 to 0.69). 2 studies that compared patients receiving low-molecular-weight (LMW) heparin with untreated controls showed reduced rates of VTE (RR, 0.16; CI, 0.04 to 0.48 and RR, 0.30; CI, 0.14 to 0.57, respectively). In the larger studies, bleeding rates increased among patients having hip or knee replacement who received 1) standard heparin, 7500 U twice daily, compared with enoxaparin, and 2) logiparin, 75 anti-Xa U/kg once per day, compared with warfarin.

Conclusions

Postoperative prophylaxis for venous thromboembolism is effective in patients at risk. No studies at present have compared prophylaxis using the same regimen given before and after surgery.

Source of funding: Not stated.

For article reprint: Not available.


Commentary

VTE, a potentially fatal but preventable complication in patients having surgery, is especially frequent after orthopedic procedures. It can be prevented by several methods when started before surgery (1, 2). VTE prophylaxis is underused, possibly because of concerns about risks for bleeding from anticoagulation and uncertainty about the efficacy of VTE prophylaxis given after surgery.

This well-done critical review of the efficacy of VTE prophylaxis started after surgery provides much-needed evidence supporting the immediate use of such prophylaxis after surgery. The review by Kearon and Hirsh confirms that VTE prophylaxis with IPC or LMW heparin was highly effective when started after surgery compared with no VTE prophylaxis. VTE rates in patients who received postoperative VTE prophylaxis with warfarin, heparin, or LMW heparin were lower than VTE rates in patients who did not receive VTE prophylaxis. This review also supports the need for further research to determine the efficacy and risks of VTE prophylaxis after surgery compared with those of the same regimen started before surgery.

Physicians and surgeons who are reluctant to use anticoagulation for VTE prophylaxis because of concerns about bleeding should pay heed and start VTE prophylaxis immediately after surgery, preferably with a combination of IPC and an anticoagulation regimen (3).

Marc D. Silverstein, MD
Mayo Clinic Rochester, Minnesota