Association between Early Absolute Neutrophil Count and Level of D-Dimer among Patients with COVID-19 Infection in Central Taiwan

Thromboembolism is a critical event in patients with coronavirus disease (COVID)-19 infection and highly associated with neutrophil extracellular traps. D-dimer has been found to be an essential thromboembolism-associated biomarker; however, the association between absolute neutrophil count (ANC) and level of D-dimer in patients with COVID-19 infection remains unclear. In this study, we enrolled consecutive patients with COVID-19 admitted to Taichung Veterans General Hospital (TCVGH), a referral center in central Taiwan with 20 airborne infection isolation rooms. Spearman correlation was used to determine the association between ANC and level of D-dimer in distinct time periods. A total of 28 consecutive patients with COVID-19 infection were enrolled, and 32.1% (9/28) of them required mechanical ventilation. Patients requiring mechanical ventilation had a higher ANC (8225 vs. 3427/µL, p < 0.01) and levels of D-dimer (6.0 vs. 0.6 mg/L, p < 0.01) compared with those without mechanical ventilation. Notably, we identified five patients with image-proven thromboembolic events during the hospital course, with the number of patients with pulmonary embolism, venous thrombosis and acute ischemic stroke were 2, 1, and 2, respectively. We found that ANC within 4 days correlated with the level of D-dimer to a moderate level (r = 0.71, p < 0.05), and the association between ANC and D-dimer no longer exist after day 5. In conclusion, we found highly prevalent thromboembolic events among patients with severe COVID-19 infection in central Taiwan and identified the association between early ANC and D-dimer. More studies are warranted to elucidate the underlying mechanism.