Hypercoagulability, thromboembolic events and multi-organ injury in COVID-19 cases are thought to be due to the immunothrombosis process. Immunothrombosis degrees are determined by Neutrophil Extracellular Traps (NETs) activity, and Neutrophil Elastase (NE) is the main enzyme that triggers NETs. SOFA score and PaO2/FiO2 ratio as parameters to determine organ injury, while D-Dimer is a parameter of hypercoagulability status and has been proven as a prognostic factor to determine the severity and mortality of COVID-19 cases. This study aims to assess the influence of Neutrophil Elastase on D-Dimer, PaO2/FiO2 ratio and SOFA score in COVID-19 patients. This is an observational analytic study with a cross-sectional design. The study population was patients treated in isolation wards and ICU RSUD dr Soetomo in the period July 2020 - October 2020. Inclusion criteria were patients with a primary diagnosis of Confirmed COVID-19 through PCR examination and aged ?18 years. The study sample was taken from medical record data of COVID-19 patients for the period July 2020 - October 2020 which met the inclusion and exclusion criteria. Data collection includes NE serum levels, D-Dimer, PaO2/FiO2 ratio and SOFA score were examined upon admission to the hospital (day 0). This study includes a total of 67 subjects. The mean and standard deviation of NE serum levels 25.67 ? 19.01 ng/mL, D-Dimer 3433.54 ? 6033.15 g/L, PaO2/FiO2 ratio 178.21 ? 102.90 and SOFA score 3.75 ? 2.12. The data normality test was carried out using the Kolmogorov Smirnov test and the results of NE, D-Dimer, PaO2/FiO2 ratio and SOFA scores data were not normally distributed, so the analysis was carried out using the Spearman correlation test. The results of the Spearman correlation test showed a significant correlation between NE serum levels and D-Dimer with a strong positive correlation strength (p < 0.001; rs = 0.755); a significant correlation between NE and SOFA scores with a weak positive correlation strength (p = 0.003; rs = 0.352). There was no significant correlation between NE serum levels and PaO2/FiO2 ratio (p = 0.068). NE Serum levels have a strong positive correlation with D-Dimer, where the higher NE serum levels, the higher D-Dimer level in COVID-19 patients. There is a weak positive correlation between NE serum levels and SOFA Score, but there is no correlation between NE serum levels and PaO2/FiO2 ratio. This may be due to other factors besides NE which are more dominant in influencing PaO2/FiO2 ratio.

COVID-19

D-dimer

SOFA score

NETs

Neutrophil Elastase