The National Institutes of Health (NIH) has reported that full-dose blood thinners decreased the organ support requirements and boosted the chances of hospital discharge in moderately ill Covid-19 patients in a large, global clinical trial.
A similar benefit was not observed on the use of this therapeutic strategy in critically ill Covid-19 patients needing intensive care, NIH noted.
The trial was partially supported by the NIH unit National Heart, Lung, and Blood Institute (NHLBI).
NHLBI director Gary Gibbons said: “These results make for a compelling example of how important it is to stratify patients with different disease severity in clinical trials.
“What might help one subgroup of patients might be of no benefit, or even harmful, in another.”
Three global partners teamed up and coordinated their trial protocols to assess the effects of heparin, a blood thinner or anticoagulant.
REMAP-CAP, ATTACC and NIH-funded ACTIV-4a Antithrombotics Inpatient were the participating partners in the multi-centre trials.
Patients hospitalised with Covid-19 who were moderately or critically ill received either a full/therapeutic dose or a low/prophylactic dose of heparin for 14 days.
An interim analysis suggested that full-dose anticoagulation failed to lower organ support requirements and could cause harm in critically ill subjects, NIH said.
All 2,219 moderately and 1,098 critically ill subjects were assessed for up to 21 days after enrolment to evaluate the duration for which they were free of organ support.
Data showed that in moderately ill subjects, full-dose heparin had a 99% chance of reducing the requirement for organ support versus low-dose heparin.
Few subjects had rarely occurring major bleeding events, NIH added.
The full dose of the blood thinner lowered the number of major thrombotic events in critically ill patients but did not mitigate organ support needs or boost the chances of early hospital discharge.
ACTIV-4a Antithrombotics Inpatient study chair Judith Hochman said: “The formal conclusions from these studies suggest that initiating therapeutic anticoagulation is beneficial for moderately ill patients and once patients develop severe Covid-19, it may be too late for anticoagulation with heparin to alter the consequences of this disease.
“The medication evaluated in these trials is familiar to doctors around the world and is widely accessible, making the findings highly applicable to moderately ill Covid-19 patients.”
This June, NIH started a new clinical study, MOMI-VAX, to assess immune responses induced by Covid-19 vaccines in pregnant or postpartum individuals.