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LMWH trumps unfractionated heparin in reducing posttrauma thrombotic events


Key clinical point: Low-molecular-weight heparin reduced the risk of deep vein thrombosis, pulmonary thromboembolism, and venous thromboembolism, and cut the risk of death as well.

Major finding: Overall mortality was reduced by 37% with LMWH, compared with unfractionated heparin.

Data source: The review comprised 37,868 patients included in the Michigan Trauma Quality Improvement Program.

Disclosures: Dr. Jacobs had no financial disclosures.



– Low-molecular-weight heparin (LMWH) decreased the risk of venous thromboembolism in trauma patients significantly more than did unfractionated heparin, a large state database review has found.

It also was associated with a 37% decrease in overall mortality, compared with unfractionated heparin, Benjamin Jacobs, MD, said at the annual scientific assembly of the Eastern Association for the Surgery of Trauma.

Dr. Benjamin Jacobs
Dr. Benjamin Jacobs
“Given these data, we feel that LMWH should be the preferred prophylactic agent in patients with trauma,” said Dr. Jacobs of the University of Michigan, Ann Arbor.

He extracted data describing thromboembolism prophylaxis among 37,868 trauma patients included in the Michigan Trauma Quality Improvement Program from 2012 to 2014. The patients were treated at 23 hospitals around the state. They received either unfractionated or LMWH as their only clot-preventing protocol.

The primary outcomes of the study were reductions in the risk of venous thromboembolism (VTE), deep vein thrombosis (DVT), pulmonary thrombosis (PT), and mortality.

LMWH was given at either 40 mg every day or 30 mg twice a day. The comparator was unfractionated heparin at 5,000 U either two or three times a day.

The preferred method was LMWH, which 83% of patients received, compared with 17% who got the unfractionated heparin. Most patients who got LMWH received the 40 mg/day dose (70%). Most who got unfractionated heparin received 5,000 U three times a day (87%).

Both types of heparin reduced the risk of all thromboembolic outcomes, and both doses of LMWH significantly reduced the risks. However, the 40 mg/day dose was significantly more effective than the twice-daily 30-mg dose in reducing the risk of VTE and DVT. Risk reductions for PT and mortality were not significantly different between the doses.

Overall, compared with unfractionated heparin, LMWH decreased the risk of VTE by 33%; of PT by 48%; and of DVT by 27%. It also conferred a significant mortality benefit, reducing the risk of death by 37%, compared with the unfractionated type

When Dr. Jacobs grouped the patients according to Injury Severity Score (ISS), he saw a consistently higher benefit among patients with lower scores. For example, LMWH significantly reduced the risk of PT by 59% in patients with an ISS of 5-14. In those with an ISS of 25 or higher, the drug was associated with a 20% increased risk, although that wasn’t statistically significant.

There was a similar finding in DVT. LMWH reduced the risk by 18% in those with an ISS of 5-15, and by 50% among those with an score of 16-24 – both significant reductions. Among those with an ISS of at least 25, the risk was 18% higher, although, again, it was not a significant finding.

Curiously, the mortality benefit was stronger among sicker patients. The benefit was nonsignificant among those with an ISS of less than 25 but for those above 25, the mortality risk reduction was a significant 45%.

Dr Jacobs had no financial disclosures.

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