Real World Outcomes of Sars-Cov-2 Thrombosis Rates across Three University Health Systems in the Chicago Metropolitan Area

Introduction: Initial studies from Wuhan, China reported patients infected with SARS-CoV-2 have uncontrolled coagulopathy and an increased risk for thrombotic complications, including pulmonary embolism (PE), deep vein thrombosis (DVT), and arterial thrombosis.¹ The incidence of thrombosis attributed to coronavirus disease 2019 (COVID-19) ranged from 9.5% in all hospital-admitted patients to 31% in the critically ill.^2,3

COVID-19 has had a major impact on the Chicago metropolitan area with over 121,000 confirmed cases as of August 2020, Cook county being the 4^th highest affected county after Maricopa, Miami-Dade and Los Angeles counties.⁴ The primary goal of this study is to describe the rate of thrombotic events in the Chicago metropolitan area, highlighting an ethnically diverse population, and identify new risk factors for thrombosis between three university health systems.

Methods: We conducted a retrospective analysis between three university health systems in the Chicago metropolitan area: Loyola University Health System (LUHS): comprised of one tertiary and two community hospitals, Rush University System for Health (RUSH): comprised of one tertiary and two community hospitals, and University of Illinois-Chicago (UIC): a tertiary hospital. All patients had positive SARS-CoV-2 testing and were hospitalized for COVID-19. PE, DVT or arterial thrombosis were confirmed by supportive imaging modalities. Wilcoxon rank sum test were used to test the associations of continuous variables; Chi-square test or Fisher’s exact test were used to test the associations of categorical variables. All analyses were performed with SAS 9.4 and two-sided p-value < .05 were deemed statistically significant.

Results: Between March and May 2020, 2,180 patients from LUHS, RUSH and UIC were hospitalized for COVID-19 and were included in our analysis. Baseline patient demographics are described in Table 1. Race/ethnicity demographics are as follows: Hispanics (H)/ African Americans (AA) represented 47%/17% of LUHS patients, 32%/42% of RUSH patients, and 36%/51% of UIC patients, respectively (Figure 1). Intensive care admissions were needed in 33% of all patients. Documented total thrombotic events are as follows: LUHS = 5.4% (41 VTE/PE, 10 arterial and 5 with both venous and arterial); RUSH = 9.7% (70 VTE/PE, 7 arterial and 4 with both venous/arterial); UIC = 6% (14 VTE/PE, 4 arterial and 0 with both venous/arterial). Patients that developed a thrombotic event were similar by age, sex, and BMI to those without a thrombotic event. Anticoagulation prophylaxis was given to 82% of pts at LUHS and UIC at time of admission. Collectively, those with thrombotic events (N=156) had higher incidence of intensive care admission, elevated white blood cell (WBC) count and a d-dimer >5X upper limit normal (ULN) at presentation. Furthermore, a higher proportion of pts that had a thrombotic event were diabetic at LUHS and RUSH (Table 2). Mortality in COVID-19 patients was 13-16% and patients that had a thrombotic event had a higher risk of death in the RUSH and UIC cohorts.

Conclusions: In a racially diverse, multi-institutional cohort of patients, we demonstrate that 7.2% of COVID-19 patients had a thrombotic event. Consistent risk factors for thrombosis across the different centers included an initial d-dimer levels >5X ULN, elevated initial WBC count, diabetes, and being critically ill. Mortality differences and anticoagulation practices between the institutions as well as race/ethnicity differences regarding thrombosis will be explored in future combined multivariate analyses. Finally, based off these risk factors, identification of patients at most risk for thrombosis is needed to reduce the morbidity and mortality when diagnosed with COVID-19.

References

• Tang et. al. J Thromb Haemost. 2020;18:844-847.
• Klock et. Al. Thrombosis Research 2020;191:145-147.
• Al-Samkari H, Laef RS, Dzik WH et. Al. COVID-19 and coagulation: bleeding and thrombotic manifestations of SARS-CoV-2 infection. Blood. 2020;136(4):489-500.
• https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/county-map.html; accessed 8/7/20.