Venous thromboembolism after hospitalization for COVID-19: venous thrombosis virtual surveillance in COVID study

COVID-19 induces a prothrombotic state that increases the risk of venous thromboembolism (VTE) in hospitalized patients, but the incidence of postdischarge VTE is not well characterized in prospective studies.

To determine the incidence of symptomatic VTE after hospitalization with COVID-19 infection.

The Venous Thrombosis Virtual Surveillance in COVID (VVIRTUOSO) study was a prospective multicenter cohort study (2021 to 2022) conducted at 6 sites in Canada. Patients ≥18 years, hospitalized for laboratory-confirmed COVID-19 or diagnosed during hospitalization within 1 week of hospital discharge, were included and followed virtually for 90 days (telephone or video). Exclusion criteria included unconfirmed diagnosis of COVID-19, no access to a telephone, computer, or tablet for virtual assessment, therapeutic-dose anticoagulation after hospital discharge, or patients (or their delegate) unable or unwilling to provide informed consent. The primary outcome was symptomatic, objectively confirmed acute VTE at 90 days. Secondary outcomes included 30-day incidence of symptomatic VTE, major bleeding, clinically relevant non-major bleeding, and mortality.

A total of 513 participants were enrolled, and 411 participants completed 90-day follow-up. Mean age was 58 years and 46% were females. At 90 days, the cumulative incidence of symptomatic VTE was 0.90% (95% CI, 0.30%-2.18%). The cumulative incidence of major bleeding was 0.20% (95% CI, 0.02-1.10), clinically relevant non-major bleeding was 1.47% (95% CI, 0.66-2.90), and mortality was 3.19% (95% CI, 1.86-5.08).

The incidence of symptomatic VTE after hospitalization with COVID-19 infection is low. Our findings suggest that routine postdischarge pharmacological thromboprophylaxis may not offer net clinical benefit for unselected patients.