COVID Clot Prevention: Hit It Early

Starting heparin prophylaxis within 24 hours of admission for COVID-19 was linked to substantially better outcomes in a VA study.

Early anticoagulation was associated with 27% lower relative risk of 30-day mortality than no anticoagulation (14.3% vs 18.7%, HR 0.73, 95% CI 0.66-0.81), Christopher Rentsch, PhD, of the London School of Hygiene & Tropical Medicine and VA Connecticut Healthcare System in New Haven, and colleagues reported in The BMJ.

Preventive heparin use held similar advantages for inpatient mortality (HR 0.69, 95% CI 0.61-0.77) as well as initiation of therapeutic anticoagulation (HR 0.81, 95% CI 0.73-0.90), the latter serving as a proxy for thromboembolic events and other clinical deterioration.

“These findings provide strong real world evidence to support guidelines recommending the use of prophylactic anticoagulation as initial treatment for patients with COVID-19 on hospital admission,” the researchers concluded.

The study included 4,297 patients admitted to VA hospitals nationwide from March 1 to July 31, 2020, with laboratory-confirmed severe acute SARS-CoV-2 infection and no history of anticoagulation.

The 84% who got early prophylaxis were sicker overall at hospital presentation than those who didn’t get anticoagulation (with a higher proportion having oxygen saturation under 93%, high heart rate, and fever) but lower comorbidity burden. Results were weighted for probability of treatment.

Early prophylaxis was not associated with more bleeds resulting in transfusion (HR 0.87, 95% CI 0.71-1.05).

Notably, the mortality advantage of anticoagulation seemed to be greater for patients not admitted to the ICU within 24 hours of hospital admission, echoing recent trials where more anticoagulation appeared not helpful and potentially harmful within the ICU.

Rentsch’s group pointed to recommendations in favor of prophylactic anticoagulation after admission for COVID-19 from groups including the American Society of Hematology, International Society on Thrombosis and Haemostasis, and CHEST Guideline and Expert Panel, as long as patients do not have a contraindication.

Dosing strategies have varied widely from center to center, but results emerging from large platform trials supporting full therapeutic dose anticoagulant prophylaxis in non-ICU admissions for COVID-19 are expected to influence guidelines, once published.

“These studies enable us to slowly hone in on who should get what anticoagulant dose,” hematologist Stephan Moll, MD, of the University of North Carolina in Chapel Hill, told MedPage Today. His summary of who should get what anticoagulation with the latest data was:

• Not sick enough to be in the hospital: No prospective data is available yet. If at low risk for deep vein thrombosis or pulmonary embolism (DVT/PE), no anticoagulation. If at high risk for DVT/PE, consider low-dose anticoagulation

• Sick enough to be in the hospital, but not in the intensive care unit: Full-dose anticoagulation

• Sick enough to be in the intensive care unit: Full-dose blood thinners are not beneficial; perhaps use low-dose or intermediate-dose anticoagulation in these patients

• Post-discharge: No prospective data is available yet. If at low risk for DVT/PE, no anticoagulation. If at higher risk for DVT/PE as assessed by IMPROVE-VTE Score, consider low-dose anticoagulation for up to 30 days

Last Updated February 11, 2021