Many surgical patients may be receiving anticoagulants they don’t need, according to research published in Annals of Surgery.
The study challenges standard of care guidelines, which recommend that all general surgery patients receive treatment to prevent venous thromboembolism (VTE).
The new findings suggest that anticoagulants may be unnecessary for most surgical patients and could even be harmful to some.
“A ‘one-size-fits-all approach’ doesn’t always make sense,” said study author Christopher Pannucci, MD, of the University of Utah in Salt Lake City.
“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.”
Dr Pannucci and his colleagues reviewed data from 13 studies to determine which surgical patients were most likely, and least likely, to benefit from anticoagulants. There was data on VTE events in 11 studies (n=14,776) and data on clinically relevant bleeding in 8 studies (n=7590).
In most of the studies, patients received mechanical VTE prophylaxis, which meant elastic compression and/or sequential compression devices.
Some studies compared mechanical prophylaxis to anticoagulants, including heparin, low-molecular-weight heparin, direct factor Xa inhibitors, direct thrombin inhibitors, warfarin, dextran, and aspirin.
The studies included a broad range of surgical patients, from individuals with few VTE risk factors to those with multiple risk factors, such as obesity, advanced age, and personal or family history of VTE.
The patients were divided into 1 of 5 categories indicating overall VTE risk. Assessment was based on the Caprini score.
VTE risk without anticoagulant treatment
There were 11 studies in which some patients did not receive anticoagulants (n=6085).
Among these patients, those who were classified as having the highest risk of VTE were 14 times more likely to develop VTE than patients in the low-risk category—10.7% vs 0.7%.
These findings were independent of surgery type.
“It was eye-opening to see that there is this huge variability in risk among the overall group of patients that walk into your office,” Dr Pannucci said. “Unless you consider a patient’s risk based on their individual factors, you would never know.”
VTE outcomes by risk score
When given, anticoagulants did significantly reduce the risk of VTE for the overall study population and for high-risk patients.
The odds ratios (ORs) were 0.66 (P=0.001) for the overall population, 0.60 (P=0.04) for patients with Caprini scores of 7 to 8, and 0.41 (P=0.0002) for patients with scores higher than 8.
Unfortunately, anticoagulants did not make a significant difference in VTE rates for mid- or low-risk patients.
The ORs were 0.45 (P=0.31) for patients with Caprini scores of 0 to 2, 1.31 (P=0.57) for patients with scores of 3 to 4, and 0.96 (P=0.85) for patients with scores of 5 to 6.
Risk of bleeding
Anticoagulants significantly increased clinically relevant bleeding for the overall population. The OR was 1.69 (P=0.006).
Patients who received anticoagulants were not significantly more likely to have clinically relevant bleeding if they had risk scores of 0 to 2 (OR=2.47, P=0.61), 3 to 4 (OR=1.05, P=0.87), 5 to 6 (OR=2.10, P=0.06), 7 to 8 (OR=3.15, P=0.16), or >8 (OR=2.31, P=0.16).
“For the first time, we have data that prophylaxis for the highest-risk groups is beneficial, and data that suggests that lower-risk patients may need no prophylaxis,” said study author Peter Henke, MD, of the University of Michigan in Ann Arbor.
He and his colleagues noted, however, that prospective studies are needed to confirm these findings.
