VTE Chemoprophylaxis Not Needed for 75% of Surgery Patients

Diana Swift

January 26, 2017

Routinely providing perioperative chemoprophylaxis for venous thromboembolism (VTE) to all surgical patients is not only unnecessary but also can be risky, as it may increase bleeding complications, a meta-analysis suggests.

The findings, published online January 19 in the Annals of Surgery, call into question the routine use of chemoprophylaxis in the overall surgical population as the risk-benefit relationship is unclear or unfavorable.

"These data argue strongly for a precision medicine approach to VTE chemoprophylaxis, where the intervention is guided by the risk/benefit relationship at the patient level," write Christopher J. Pannucci, MD, a plastic surgeon and an assistant professor of surgery at the University of Utah in Salt Lake City, and colleagues.

The analysis of 13 studies included 14,776 surgical patients, most of whom received mechanical prophylaxis. Anticlotting agents covered in the analysis included heparin, low-molecular-weight heparin, direct factor Xa inhibitors, direct thrombin inhibitors, warfarin, dextran, and acetylsalicylic acid.

When the researchers stratified the patients based on 2005 Caprini scores for VTE risk, they found a 14-fold variation in risk between the lowest, at 0.7%, and the highest, at 10.7%. As expected, the incidence of VTE increased with increasing Caprini scores.

Overall, chemoprophylaxis reduced the risk for postoperative VTE by 34% (odds ratio [OR], 0.66; 95% confidence interval [CI], 0.52-0.85; P = .001).

However, when stratified by Caprini score, the benefit associated with chemoprophylaxis was restricted to those with a score of 7 or higher. Patients with Caprini scores of 6 or less made up 75% of the overall population, and these patients experienced no significant risk reduction with chemoprophylaxis.

Table.

Caprini Score OR 95% CI P Value
0 - 2 0.45 0.10 - 2.09 .31
3 - 4 1.31 0.51 - 3.31 .57
5 - 6 0.96 0.60 - 1.53 .85
7 - 8 0.60 0.37 - 0.97 .04
>8 0.41 0.26 - 0.65 .0002

When the investigators looked at the risk for clinically relevant bleeding, they found that among 4390 patients who did not receive chemoprophylaxis the rate was 1.8%.

Among those who received chemoprophylaxis, the overall risk for clinically significant bleeding increased (OR, 1.69; 95% CI, 1.16 - 2.45; P = .006). Risk-stratified analysis showed no significant association between chemoprophylaxis and clinically relevant postoperative bleeding at any Caprini score.

"Patients with Caprini scores of ≤6, which includes ~75% of surgical patients, have an unfavorable or unknown risk/benefit relationship," write Dr Pannucci and colleagues. They note that more precisely targeted use of chemoprevention based on individualized VTE risk stratification will ensure more appropriate use of drugs and help reduce bleeding complications.

Although three of four patients overall may no require postoperative chemoprophylaxis, the authors warn that risk reassessment may be necessary in patients with postoperative complications such as pneumonia and urinary tract infections.

"A 'one-size-fits-all approach' doesn't always make sense," Dr Pannucci said in a related press release. "A healthy 35-year-old is very different from someone who is 85 and has a history of clots. Our research indicates that there could be a substantial number of people who are being over-treated."

Previously, two 2014 US studies reported that in light of the low rates of VTE, preventive drugs were being overprescribed, thereby exposing some patients to bleeding complications. And a 2013 analysis found nearly identical VTE rates in hospitals with both high and low use of VTE prophylaxis.

Dr Pannucci receives financial support from the Agency for Healthcare Research and Quality and the American Association of Plastic Surgeons/Plastic Surgery Foundation. The other authors have disclosed no relevant financial relationships.

Ann Surg. Published online January 19, 2017. Abstract

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