Table 2.
Clinical characteristics of case–control sample
| Inpatients with COVID-19 | VTE-positive (N=21) |
VTE-negative (N=42) |
p-value |
|---|---|---|---|
| Age [mean (SD)]* | 67 (12) | 65 (15) | 0.32 |
| Female sex [n (%)] | 7 (33) | 18 (43) | 0.47 |
| Comorbidities | |||
| Cardiovascular disease [n (%)] | 6 (29) | 9 (21) | 0.53 |
| Diabetes [n (%)] | 8 (38) | 10 (23) | 0.23 |
| Pulmonary disease [n (%)] | 8 (38) | 9 (21) | 0.16 |
| Renal disease [n (%)] | 4 (19) | 6 (14) | 0.63 |
| Malignancy [n (%)] | 4 (19) | 6 (14) | 0.63 |
| Immunosuppression [n (%)] | 2 (10) | 3 (7) | 0.74 |
| Admission to critical care [n (%)] | 6 (29) | 14 (33) | 0.70 |
| Laboratory parameters | |||
| CRP mg/L [median (IQR)] | 122 (188) | 78.5 (101) | 0.09 |
| White cell count ×109/L [median (IQR)] | 11.1 (4.6) | 7.2 (4.5) | 0.009 |
| Lymphocytes ×109/L [median (IQR)] | 0.9 (0.7) | 0.9 (0.6) | 0.95 |
| D-dimer μg/mL [median (IQR)] | 4.1 (6.0) | 1.2 (2.0) | <0.001 |
| APTT ratio [median (IQR)] | 1.1 (0.1) | 1.2 (0.3) | 0.72 |
| Fibrinogen g/L [mean (SD)]* | 6.8 (2.2) | 6.6 (1.8) | 0.7 |
| INR [median (IQR)] | 1.1 (0.2) | 1.05 (0.1) | 0.02 |
Sequentially diagnosed patients without VTE diagnosis as of 9 April 2020 were selected as controls at a ratio of 2:1. Three cases without measurements of D-dimer, APTT ratio or fibrinogen were included in the analysis. Control patients were excluded if data was incomplete. Control patients were selected at a ratio of 2:1 swab positive (28) to swab negative (14) to match the distribution of cases. D-dimer above 20 was recorded as 20 for the purposes of analysis. Normally distributed data is marked with an asterisk (*). Proportions were analysed by Z-test, normally distributed variables by unpaired T-test and non-parametric variables by Mann–Whitney test. APTT = activated partial thromboplastin time; CRP = C-reactive protein; INR = international normalised ratio; IQR = interquartile range; SD = standard deviation; VTE = venous thromboembolism.