Therapeutic levels of heparin can have widely varying effects on COVID-19 patients depending on the severity of their disease, according to a multiplatform clinical trial that analyzed patient data from three international trials.
COVID-19 patients in the ICU, or at least receiving ICU-level care, derived no benefit from anticoagulation with heparin, while non–critically ill COVID-19 patients – those who were hospitalized but not receiving ICU-level care – on the same anticoagulation were less likely to progress to need respiratory or cardiovascular organ support despite a slightly heightened risk of bleeding events.
Reporting in two articles published online in the New England Journal of Medicine, authors of three international trials combined their data into one multiplatform trial that makes a strong case for prescribing therapeutic levels of heparin in hospitalized patients not receiving ICU-level care were non–critically ill and critically ill.
“I think this is going to be a game changer,” said Jeffrey S. Berger, MD, ACTIV-4a co–principal investigator and co–first author of the study of non–critically ill patients. “I think that using therapeutic-dose anticoagulation should improve outcomes in the tens of thousands of patients worldwide. I hope our data can have a global impact.”
Outcomes based on disease severity
The multiplatform trial analyzed data from the Antithrombotic Therapy to Ameliorate Complications of COVID-19 (ATTACCREMAP-CAP).
The trial evaluated 2,219 non–critically ill hospitalized patients, 1,181 of whom were randomized to therapeutic-dose anticoagulation; and 1,098 critically ill patients, 534 of whom were prescribed therapeutic levels of heparin.
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In the critically ill patients, those on heparin were no more likely to get discharged or spend fewer days on respiratory or CV organ support – oxygen, mechanical ventilation, life support, vasopressors or inotropes – than were those on usual-care thromboprophylaxis. The investigators stopped the trial in both patient populations: in critically ill patients when it became obvious therapeutic-dose anticoagulation was having no impact; and in moderately ill patients when the trial met the prespecified criteria for the superiority of therapeutic-dose anticoagulation.
ICU patients on therapeutic-level heparin spent an average of 1 day free of organ support vs. 4 for patients on usual-care prophylactic antithrombotic drugs. The percentage of patients who survived to hospital discharge was similar in the therapeutic-level and usual-care critically ill patients: 62.7% and 64.5%, respectively. Major bleeding occurred in 3.8% and 2.8%, respectively. Demographic and clinical characteristics were similar between both patient groups.
However, in non–critically ill patients, therapeutic levels of heparin resulted in a marked improvement in outcomes. The researchers estimated that, for every 1,000 hospitalized patients with what they labeled moderate disease, an initial treatment with therapeutic-dose heparin resulted in 40 additional patients surviving compared to usual-care thromboprophylaxis.
The percentages of patients not needing organ support before hospital discharge was 80.2% on therapeutic-dose heparin and 76.4% on usual-care therapy. In terms of adjusted odds ratio, the anticoagulation group had a 27% improved chance of not needing daily organ support.
Those improvements came with an additional seven major bleeding events per 1,000 patients. That broke down to a rate of 1.9% in the therapeutic-dose and 0.9% in the usual-care patients.
As the Delta variant of COVID-19 spreads, Patrick R. Lawler, MD, MPH, principal investigator of the ATTACC trial, said there’s no reason these findings shouldn’t apply for all variants of the disease.
Dr. Lawler, a physician-scientist at Peter Munk Cardiac Centre at Toronto General Hospital, noted that the multiplatform study did not account for disease variant. “Ongoing clinical trials are tracking the variant patients have or the variants that are most prevalent in an area at that time,” he said. “It may be easier in future trials to look at that question.”
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