After receiving approval from the Ministry of Health and the local ethics committee, we included 80 patients who were found to be COVID-19 positive by polymerase chain reaction (PCR) test in our clinic between May 15, 2020 and June 15, 2020; their written consents were obtained. The patients were followed up clinically by transferring them to the service reserved for COVID-19 positive patients.
Inclusion criteria: Patients older than 18 years, who were diagnosed with COVID-19 and were administered LMWH, and agreed to participate in the study were included
Exclusion criteria: Patients with previous coagulopathy, continuous indication of anticoagulant therapy (atrial fibrillation (AF), valve disease), glomerular filtration rate (GFR) <30 mL/min or undergoing dialysis, or with known liver dysfunction were excluded from the study.
COVID-19 was diagnosed according to the WHO interim guidelines and confirmed in our laboratory by SARS-CoV-2 RNA detection with reverse-transcriptase polymerase-chain-reaction (RT-PCR) using nasal and pharyngeal swab samples .
Patients with a systolic blood pressure (SBP) of ≥140 mmHg and/ or a diastolic blood pressure (DBP) of ≥90 mmHg, and those using antihypertensive drugs were considered hypertensive. Patients using oral antidiabetics or insulin, or exhibiting fasting blood glucose ≥126 mg/dl in two measurements were considered diabetic. Body mass indices (BMI) were calculated according to the following formula:
BMI = body weight (kg)/ square of the height (m²). GFR was calculated using the Cockcroft-Gault formula: GFR = [(140 - age) x patient weight (kg)]/[72 x serum creatinine value] (x 0.85 for women) .
Demographic characteristics of the hospitalized patients with COVID-19 were recorded and computerized tomography (CT) of thorax were evaluated. Blood samples were collected to evaluate the hematological, inflammatory, and biochemical parameters of the patients (Figure 1). Electrocardiograms (ECG) were recorded and O2 saturation was determined.
Treatment of patients with enoxaparin was arranged based on the results of laboratory tests, thorax CT, and clinical evaluation. Enoxaparin dosage of 0.5 mg/kg (2x1) was administered to patients with increased inflammation parameters and D-dimer levels, as well as pneumonic infiltration in thorax. Enoxaparin dosage of 40 mg (1x1) was administered to the other patients. Other treatments were determined based on the recommendations of infectious disease specialists.
We determined the levels of anti-Factor Xa in the blood collected from COVID-19 patients 4 h after the 3rd LMWH dose. An anti-Factor Xa level of <0.2 IU/mL was defined as subprophylactic [15,16].
Patients with decreased O2 saturation and progressing disease state were taken to the intensive care unit. Control anti-Factor Xa levels in the blood collected 4 h after administering the last LMWH dose before discharge were measured (Figure 1).
Hematological parameters were examined with Mindray BC 6800 whole blood device (Mindray, China). The BC-6800 hematology analyzer used sheath flow impedance, laser scatter, and SF Cube analysis technology. The SF Cube analysis technology is three-dimensional using information from laser light scatter at two angles and fluorescent signals for cell differentiation and counting. In addition, the accuracy of cell numbers was confirmed by peripheral smear from blood samples taken from patients. Biochemical parameters were examined with Cobas C702 (Roche Diagnostics, Mannheim, Germany) device. CRP was examined with BN II nephelometer System (Siemens Healthcare Diagnostics Inc., USA). D-dimer:fibrinogen ratio was examined by the Sysmex CS-5100 device.
The levels of anti-factor Xa were measured from the obtained plasma samples using the Berichrom Heparin kit in a Sysmex cs 5100 device in the biochemistry laboratory. The Berichrom Heparin kit is a chromogenic test (Berichrom heparin, Siemens Healthineers, Marburg, Germany). INR (International Normalised Ratio), PT (Prothrombin Time), and aPTT (activated Partial Thromboplastin Time) were measured as coagulation parameters. Venous blood samples in coagulation tubes were centrifuged at 5000 rpm for 10 min, and the INR, PT, and aPTT levels were measured in the biochemistry laboratory using a Sysmex cs 5100 device, Dade Actin FS, activated PTT reagent, and thromborel S reagent.
The patients whose general condition was stable, had reduced complaints, and had a decrease in inflammatory parameters were discharged. Patients with D-dimer values above 0.5 µg/mL during discharge were administered a single dose of enoxaparin (40 mg, 1x1) for 30 days. Patients with lung involvement during hospitalization were given moxifloksain (400 mg, 1x1) or amoxicillin (1000 mg, 2x1) for 1 week at discharge. After discharge, these patients were examined at home by filiation teams for 14 days.
The data were analyzed using the SPSS 23.0 statistics package (SPSS Inc, Chicago, IL, USA). Continuous variables have been reported as mean ± standard deviation, and categorical variables have been reported as percentages. In comparing the averages between groups, Student’s t test was used for variables with a normal distribution, and the Mann-Whitney U test was used for variables without a normal distribution. Categorical variables were compared with the chi-squared test or Fisher's exact test. The sensitivity and specificity of eosinophil to predict subprophylactic levels of anti-factor Xa were analyzed by receiver operating characteristic (ROC) analysis. P values <0.05 were considered significant.