Incidence, Risk Factors, and Timing of Macrovascular Thrombosis in the Post-COVID-19 Elderly and Assessing the Need and Duration of Extended Thromboprophylaxis: A Prospective Study

Background: COVID-19 infection causes a wide spectrum of macrovascular thrombosis, which has contributed significantly to morbidity and mortality in the elderly. Guidelines have recommended extended prophylaxis following discharge from the hospital for variable periods. The risk of thrombosis and the optimal duration of extended anticoagulation remain uncertain. Objectives: This study aimed at determining the overall incidence and timing of macrovascular thrombosis in post-COVID-19 elderly patients. It also aimed at finding out the predictive value of clinical severity, in-hospital anticoagulation, and discharge Ddimer values for the incidence of macrovascular thrombosis and overall mortality within 13 weeks following clinical recovery from acute COVID-19 infection in the elderly. Methods: In this study, 288 elderly patients with symptomatic acute COVID-19 infection discharged between August 1, 2020, and November 30, 2020, were enrolled. Details regarding the incidence of macrovascular thrombosis were collected through a telephone interview after 90 days. Data were tabulated and analyzed with IBM SPSS Statistics for Windows, Version 23.0. (Armonk, NY: IBM Corp.) Results: The number of macrovascular thrombotic events was significantly higher in group C (critical illness) than in the other two groups (17.9 vs. 1.8 and 1.1%, respectively) (P = 0.0005). Three (10.7%) patients died within 13 weeks of discharge in group C, versus one (0.6%) patient in groupM(mild to moderate illness) and none in group S (severe illness) (P = 0.0005). There were two macrovascular thrombotic events in the elevated D-dimer group versus one in the reduced D-dimer group (P = 0.135). The number of deaths was high in the elevated D-dimer group [2 (8.3%) vs. 0 (0), P = 0.053]. The cumulative incidence rate of macrovascular events in the post-COVID-19 elderly cohort 13 weeks after discharge was 3.12%. Conclusions: Elderly patients with a critical illness during hospitalization due to COVID-19 and elevated D-dimer values at discharge have the maximum risk of developing macrovascular thrombosis in the post-COVID-19 period. It is reasonable to recommend extended thromboprophylaxis for at least eight weeks in the post-COVID-19 elderly.