Prevention and Treatment of Venous Thromboembolism Key Clinical Questions
06. What is the optimal prophylaxis strategy (dosing, route of administration, frequency) in COVID-19+ patients?
a. HOMERuN institutions
Nineteen percent of protocols recommended standard pharmacologic VTE prophylaxis dosing for all COVID-19 patients regardless of estimated VTE risk. Ten percent recommended higher-than-standard prophylaxis dosing regardless of estimated VTE risk. Fifty-seven percent of protocols recommended a tiered prophylactic VTE dosing strategy, with standard and higher-intensity dosing based on estimated VTE risk. However, recommendations for higher-intensity dosing varied: for non-obese patients with normal renal function, the four intensified prophylaxis regimens recommended were: enoxaparin 30mg subcutaneously every 12 hours (19%), enoxaparin 40mg subcutaneously every 12 hours (19%), enoxaparin 1mg/kg subcutaneously daily (10%), or enoxaparin 0.5mg/kg subcutaneously every 12 hours (10%). With regard to criteria for higher prophylaxis dosing, 43% protocols recommended selecting patients based on elevated D-dimer or fibrinogen with or without additional clinical criteria, and the remaining protocols used clinical criteria alone to support prophylaxis intensification.
b. What is Known
Observational data to date demonstrate that the risk of VTE appears increased in COVID-19 patients, especially those in the ICU, with case series showing an incidence of 18%-49% on varying levels of prophylactic anticoagulation. This compares to a historical rate of 7%-10% among critically ill patients on pharmacologic VTE prophylaxis.15
c. What is Not Known
The optimal strategy for prevention of VTE in patients hospitalized with COVID-19 remains uncharted. Although failure rates using standard anticoagulant doses appear higher than historical controls, whether higher-intensity or even treatment-dose anticoagulation will mitigate this risk or expose patients to undue harm remains unknown. Escalated dosing strategies are mostly extrapolated from trauma and surgical patients and thus have not been evaluated in this setting. Moreover, the best way to select patients who merit intensified prophylaxis remains unclear. Randomized controlled trials comparing strategies are underway.
Key Clinical Questions
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- Lim W, Meade M, Lauzier F, et al. Failure of anticoagulant thromboprophylaxis: risk factors in medical-surgical critically ill patients*. Crit Care Med. 2015;43(2):401-410. doi:10.1097/CCM.0000000000000713