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Study provides safety info about use of enoxaparin thromboprophylaxis
Longer treatment is safer for some patients
New research suggests that hospitals and clinical pharmacists might improve safety if they change policies regarding the use of extended-duration enoxaparin thromboprophylaxis in acutely ill patients.
The study shows that some acutely-ill medical patients benefit from thromboprophylaxis treatment that lasts longer than one or two weeks. Hospital pharmacists should bring this latest research to the attention of their hospital pharmacy and therapeutics (P&T) committees for discussion.
"We already know that the risk of blood clots in the veins is high in acutely ill medical patients in the hospital," says Roger D. Yusen, MD, MPH, an associate professor of medicine in the division of pulmonary and critical care medicine at Washington University School of Medicine in St. Louis, MO.
"There's a strong body of literature that supports that the benefits outweigh the risks in using medicines to prevent the formation of these blood clots, known as deep vein thrombosis (DVT)," Yusen adds. "DVT have the risk of breaking off and ending up in the lungs as pulmonary embolism (PE)."
DVT causes problems with swelling, pain, and ulcers in the legs, but most importantly raise the risk of future blood clots and a spectrum of diseases, including PE, pulmonary arterial hypertension, and death, he says.
While hospitals and physicians have a body of experience and literature supporting standard methods for treating or preventing DVT, the length of such treatment is less clear, Yusen says.
"The main studies have suggested that the medicines should be given for duration of six to 14 days to prevent blood clots in acutely ill patients in the hospital, and that's what the FDA has approved," he explains.
Studies have shown that the benefits outweigh the risks in giving high-risk, surgical patients thromboprophylaxis for an extended period of time, such as for a month. So Yusen and co-investigators looked at whether an extended-duration thromboprophylaxis might also benefit acutely-ill medical patients.
They found in a study that enrolled 7,500 patients that there were benefits to this approach, particularly for patients who were women, over age 75, and for those who had been on complete bed rest for at least a day.1
"The main findings were the extended-duration thromboprophylaxis reduced the incidence of thromboembolism when compared to placebo," Yusen says. "The rate was 2.5% for extended duration, versus 4.0% for placebo."
Also, extended-duration thromboprophylaxis increased the risk of bleeding as was expected, but the rates were very low, with bleeding rates of 0.8% with the extended-duration treatment versus 0.3% in the placebo group, he adds.
"For women, the venous thromboembolism rate was 4.6% for placebo versus 1.9% for those receiving extended prophylaxis," Yusen says. "For patients older than 75 years the clot rate was 6.7% with placebo, versus 2.5% with extended duration prophylaxis."
Bleeding risks for both groups were higher with the extended prophylaxis, but again were overall very small.
"Even in the elderly, the clot risk outweighs the bleeding risk," Yusen says.
Patients enrolled in the study received a standard course of low molecular weight heparin enoxaparin, with six to 14 days of treatment per existing guidelines, Yusen says.
Study enrollees then continued with an additional 28 days of prophylaxis or placebo in the double-blind, randomized trial. Some people dropped out of the study because of bleeding or other reasons.
Everyone received a shot once a day in or out of the hospital, and investigators followed study participants to see if they experienced blood clots or major bleeding, Yusen says.
"At the end of the double-blind treatment period, study participants underwent an ultrasound test of their legs, looking for blood clots," Yusen adds.
The research's findings highlight the point that hospitals should consider themselves still responsible for patient outcomes even after patients have been discharged to the community.
"In the old days we kept people in the hospital for weeks," Yusen says. "So now we send them home as soon as we can, and it's often before six to 14 days."
Those patients remain at risk for blood clots, so maybe their heparin shots should not end when they leave the hospital, he adds.
"People should continue their blood clot prevention longer, and they could give themselves injections of heparin at home, just as diabetics give themselves injections of insulin," Yusen says.
Any change in policy or practice should take into consideration individual patient differences, he notes.
"Consider an individual's risks for clotting and bleeding," Yusen says. "If an individual is at high risk for bleeding then it might be inappropriate to extend the prophylaxis."
Also, some patients might be overly concerned about bleeding or worried about giving themselves shots, and these concerns should be considered in any treatment decisions, he adds.
One of the study's key points is that the risk of DVT doesn't go away immediately, so clinicians should consider a long enough course of blood clot prevention to optimally protect patients. This point is underlined by the trend in many hospitals of giving the prophylaxis treatment for even fewer days than the FDA-approved regimen, Yusen notes.
"A lot of hospital clinicians only give venous thromboembolism prophylaxis for four or five days," he says. "This study drives home the point that you should at least make sure you give the standard course of thromboprophylaxis, and it might be of benefit to give a longer course for some medical patients."