High-dose prophylactic anticoagulation or therapeutic anticoagulation reduced de novo thrombosis in patients with hypoxemic COVID-19 pneumonia, based on data from 334 adults.
Patients with hypoxemic COVID-19 pneumonia are at increased risk of thrombosis and anticoagulation-related bleeding, therefore data to identify the lowest effective anticoagulant dose are needed, wrote Vincent Labbé, MD, of Sorbonne University, Paris, and colleagues.
Previous studies of different anticoagulation strategies for noncritically ill and critically ill patients with COVID-19 pneumonia have shown contrasting results, but some institutions recommend a high-dose regimen in the wake of data showing macrovascular thrombosis in patients with COVID-19 who were treated with standard anticoagulation, the authors wrote.
However, no previously published studies have compared the effectiveness of the three anticoagulation strategies: high-dose prophylactic anticoagulation (HD-PA), standard dose prophylactic anticoagulation (SD-PA), and therapeutic anticoagulation (TA), they said.
In the open-label Anticoagulation COVID-19 (ANTICOVID) trial, published in JAMA Internal Medicine, the researchers identified consecutively hospitalized adults aged 18 years and older being treated for hypoxemic COVID-19 pneumonia in 23 centers in France between April 2021 and December 2021.
The patients were randomly assigned to SD-PA (116 patients), HD-PA (111 patients), and TA (112 patients) using low-molecular-weight heparin for 14 days, or until either hospital discharge or weaning from supplemental oxygen for 48 consecutive hours, whichever outcome occurred first. The HD-PA patients received two times the SD-PA dose. The mean age of the patients was 58.3 years, and approximately two-thirds were men; race and ethnicity data were not collected. Participants had no macrovascular thrombosis at the start of the study.
The primary outcomes were all-cause mortality and time to clinical improvement (defined as the time from randomization to a 2-point improvement on a 7-category respiratory function scale).
The secondary outcome was a combination of safety and efficacy at day 28 that included a composite of thrombosis (ischemic stroke, noncerebrovascular arterial thrombosis, deep venous thrombosis, pulmonary artery thrombosis, and central venous catheter–related deep venous thrombosis), major bleeding, or all-cause death.
For the primary outcome, results were similar among the groups; HD-PA had no significant benefit over SD-PA or TA. All-cause death rates for SD-PA, HD-PA, and TA patients were 14%, 12%, and 13%, respectively. The time to clinical improvement for the three groups was approximately 8 days, 9 days, and 8 days, respectively. Results for the primary outcome were consistent across all prespecified subgroups.
However, HD-PA was associated with a significant fourfold reduced risk of de novo thrombosis compared with SD-PA (5.5% vs. 20.2%) with no observed increase in major bleeding. TA was not associated with any significant improvement in primary or secondary outcomes compared with HD-PA or SD-PA.
The current study findings of no improvement in survival or disease resolution in patients with a higher anticoagulant dose reflects data from previous studies, the researchers wrote in their discussion. “Our study results together with those of previous RCTs support the premise that the role of microvascular thrombosis in worsening organ dysfunction may be narrower than estimated,” they said.
The findings were limited by several factors including the open-label design and the relatively small sample size, the lack of data on microvascular (vs. macrovascular) thrombosis at baseline, and the predominance of the Delta variant of COVID-19 among the study participants, which may have contributed to a lower mortality rate, the researchers noted.
However, given the significant reduction in de novo thrombosis, the results support the routine use of HD-PA in patients with severe hypoxemic COVID-19 pneumonia, they concluded.