The main factors associated with disease severity in Covid-19 are age, sex, body weight, hypertension, and diabetes. Biomarkers of hemostatic activation have been shown to be independent predictors of disease severity in different populations.

To evaluate whether biomarkers of hemostatic activation were associated with clinical outcomes in patients admitted to a field hospital set up to provide initial care to patients in the early symptomatic phase of Covid-19.

Data and samples were obtained from June to September 2020. Laboratory evaluation included complete blood counts, PT, aPTT, fibrinogen, D-dimer, factor VIII activity, Von Willebrand Factor (VWF) (activity and antigen), C reactive protein (CRP) and P-selectin (ELISA). Patients were segregated by outcome, with clinical worsening defined as need for ICU, mechanical ventilation, pulmonary embolism, deep vein thrombosis or death.

In total 209 were enrolled in the study, of which 24 presented clinical deterioration (11.5%). In both groups there was more male patients. In the group of clinical worsening the mean age was 58.1 and improvement was 53.6 years old. Concerning smoking, 3.2% of patients that improved smoke. Regarding pulmonar infiltrate, it was verified in 50% in the group that worsening versus 41% in clinical improvement. No differences could be observed between patient subgroups regarding the presence of fever (63.2% vs. 62.5%), dry cough (75.1% vs. 87.5%) and dyspnea (65.9% vs. 54.2%) at admission. As main comorbidities, the groups presented chronic obstructive pulmonary disease (2.2% vs 8.3%), asthma (3.2% vs 4.2%), chronic heart failure (1.1% vs 8.3%), arterial hypertension (46% vs 41.7%) and diabetes (28.1% vs 33.3%) in comparing improved with clinical deterioration patients. In general, it was verified a significant decrease in platelet number (p = 0.0426), and an increase in the parameters of aPTT (0.0084), CRP (p = 0.0450), vWF antigen (p = 0.0022) and ristocetin cofactor (p = 0.0032).

Our results demonstrate that hemostasis activation is associated with clinical deterioration even at the early phases of Covid-19. The Ethics Research Committee of the University of Campinas approved all of the experimental procedures, and all individuals signed the informed consent form.