OC 32.3 - Age, Race, D-dimer, and Modified IMPROVE VTE Score Did Not Predict Effect of Thromboprophylaxis on Arterial Thromboembolism, Venous Thromboembolism, or Death after COVID-19 Hospitalization

Background: The Accelerating Coronavirus 2019 (COVID-19) Therapeutic Interventions and Vaccines (ACTIV)-4C trial investigated the role of prophylactic apixaban for 30 days following hospitalization with COVID-19. The overall incidence of early post-discharge death or thromboembolism was low, and the trial was closed early.

Aims: To identify a high-risk patient population who might benefit from post-discharge thromboprophylaxis, we completed subgroup analyses stratified by age, race/ethnicity, obesity, D-dimer elevation, WHO Score, and modified IMPROVE-VTE score on 30- and 90-day composite of all-cause death, arterial thromboembolism (ATE), and venous thromboembolism (VTE).

Methods: Cumulative incidence of all-cause death, ATE, and VTE within 30 days were described for each subgroup. Time to death, ATE, or VTE at 90 days were analyzed using cox proportional hazard models with interaction testing for each subgroup.

Results: 1217 patients were randomized to apixaban or placebo. Overall, 35% of participants were >60 years, 26% were Black, 17% were Hispanic, and 64% had BMI ≥30 kg/m2. D-dimer prior to hospital discharge was abnormal in 57%, and 31% of participants had a WHO severity score ≥5. Modified IMPROVE VTE score was ≥4 in 11%, and was 2-3 with an elevated D-dimer in an additional 9%. The overall incidence of the primary endpoint was 2.13% in the apixaban group and 2.31% in the placebo group. At Day 30, similar rates of the primary endpoint occurred within subgroups except for participants >60 years (Figure 1). At Day 90, trends for an effect of thromboprophylaxis were suggested based on length of hospital stay and WHO severity score, but not the IMPROVE VTE score (Table 1). Because of the low number of events, the results are inconclusive, but a high-risk subgroup who would benefit from extended thromboprophylaxis was not identified.

Conclusion(s): Subgroup analysis did not identify patients with COVID-19 that would benefit from thromboprophylaxis after hospital discharge.