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ADOPT: Apixaban not superior to enoxaparin for thromboprophylaxis
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AHA Scientific Sessions 2011
ORLANDO — Treatment with 30 days of low-dose apixaban was no more effective than a shorter course of enoxaparin for the prevention of venous thromboembolism, according to results of the ADOPT trial.
Researchers studied whether 1 month of the oral investigational blood-thinner apixaban (Eliquis, Bristol-Myers Squibb and Pfizer) was safer and more effective than 6 to 14 days of standard therapy with injectable enoxaparin in preventing venous thromboembolism. The ADOPT trial included more than 6,000 patients who were hospitalized for congestive heart failure, acute respiratory failure and other conditions that increase risk for venous thromboembolism. All were aged 40 years or older, had restricted mobility and were expected to be hospitalized for at least 3 days. Patients were randomly chosen to receive twice-daily apixaban 2.5 mg for 30 days (n=3,255) or once-daily enoxaparin 40 mg for 6 to 14 days (n=3,273).
Among the 4,495 patients for whom effectiveness data could be evaluated at 30 days, 2.7% randomized to apixaban for 30 days experienced a venous thromboembolic event, including death, deep vein thrombosis or pulmonary embolism compared with 3.1% randomized to enoxaparin (P=.44).
By 30 days, 0.47% of patients in the apixaban group experienced major bleeding vs. 0.19% in the enoxapain group (P=.04). The primary safety outcome of total bleeding events, however, showed no significant difference between treatment with apixaban (7.7%) and enoxaparin (6.8%).
"Despite a nonsignificant trend after the parenteral period in favor of extended prophylaxis, ADOPT does not provide evidence to justify such a policy in a broad population of medically ill patients," Samuel Z. Goldhaber, MD, senior cardiologist at Brigham and Women's Hospital and professor of medicine at Harvard Medical School, said at a press conference. "We need to identify high-risk subgroups that might benefit from extended venous thromboembolic prophylaxis."
Researchers did not assess mobility after discharge in this study.
"Nowadays, people are being discharged from the hospital after shorter lengths of hospital stay. When they leave, they remain at much higher risk for pulmonary embolism than in the past," Goldhaber said. "It is this gap in what to do after hospital discharge that the ADOPT trial really focused on, to try to make progress in addressing this great unmet need."
The current recommendation for enoxaparin use is 6 to 14 days, according to information in a press release issued by the American Heart Association. However, many hospitalized patients receive a shorter course of treatment because therapy is routinely stopped on discharge. With this in mind, Goldhaber said conclusions about the drug comparison should be withheld. — by Casey Murphy
For more information:
- Goldhaber SZ. LBCT.01. Presented at: American Heart Association Scientific Sessions 2011; Nov. 12-16, 2011; Orlando.
- Goldhaber SZ. N Engl J Med. 2011;doi:10.1056/NEJMoa1110899.
Disclosure: Dr. Goldhaber received research grants from Bristol-Myers Squibb, Daiichi Sankyo, Eisai, EKOS, Johnson & Johnson and Sanofi-Aventis. He is also a consultant/advisory board member for Bristol-Myers Squibb, Daiichi Sankyo, Eisai, EKOS, Merck, Pfizer, Portola and Sanofi Aventis.
It is important to understand a little bit about the epidemiology of venous thrombosis among medical inpatients in order to put the findings of this study into context. The incidence rate of symptomatic venous thromboembolism among medical inpatients before and after discharge is about 1%, with the rate of silent thrombosis as high as 10% to 20%. About half of these events occur after discharge and 3 months following discharge from hospitals. In terms of the absolute burden of this problem on venous thromboembolism, about 175,000 venous thromboemboli can be expected annually in the US in relation to medical inpatient stay. This is an important public health problem that we need to address. The critical issue is that we do not really understand which patients are at highest risk of thromboembolism associated with stay on medical inpatient services.
Mary Cushman, MD, MSc
Professor of Medicine and Pathology
University of Vermont
College of Medicine
Disclosure: Dr. Cushman reports no relevant financial disclosures.
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