Table 1. Frequency of VTE in patients with COVID-19 and related risk factors.
| First author, journal (reference) | Study design and country of its population | N, % males | Mean age | Patients in ICU (%) | Criteria for inclusion | Use of thromboprophylaxis | Indication for VTE imaging study | Rate of VTE | Risk factors related to VTE |
|---|---|---|---|---|---|---|---|---|---|
| Cui et al., J Thromb Haemost (45) | Retrospective single-centre, China | 81, 46% | 60 yrs | 100% | COVID-19 pneumonia, admission to ICU | No use of thromboprophylaxis | Not specified | 25%, all as DVT | Aged, lymphopenia, prolonged aPTT, DD |
| Maatman et al., Crit Care Med (46) | Retrospective, multi-centre, USA | 109, 57% | 61 yrs | 100% | Confirmed COVID-19 pneumonia requiring ICU | All patients received thromboprophylaxis: enoxaparin 40 mg daily, enoxaparin 30 mg b/d or UFH 5,000 IU subcutaneous heparin every 8 h | Clinical suspicion | 28% | Values at admission: Platelet count, aspartate aminotransferase lactate dehydrogenase, DD and troponin |
| Al-Samkari et al., Blood (47) | Retrospective, multi-centre, USA | 400, 57% | 62 yrs | 36% | Confirmed COVID-19 requiring hospitalization | 97% received thromboprophylaxis: standard dose: 88.5%; intermediate- or full-dose: 8.8% | Not specified | 4.8% | DD, fibrinogen, C-reactive protein, ferritin, and procalcitonin |
| Klok et al., Thromb Res (48) | Retrospective, multi-centre, Netherlands | 184, 76% | 64 yrs | 100% | COVID-19 pneumonia, admission to ICU | All patients with TP at standard dose with Nadroparin (regime varied according to centre) | Clinical suspicion (according to criteria of the clinician responsible) | 15%. Accumulated incidence 7 days of 27% (95% CI: 17–37%) | Age, coagulopathy (PT >3 seconds and/or aPTT >5 seconds) |
| Klok et al., Thromb Res (49) | Retrospective, multi-centre, Netherlands | 184, 76% | 64 yrs | 100% | COVID-19 pneumonia, admission to ICU | All patients with TP at standard dose with Nadroparin (regime varied according to centre) | Clinical suspicion | 37%. Accumulated incidence 14 days of 49% (95% CI: 41–57%) | Long-term anticoagulation was a protective factor |
| Alonso-Fernández et al., PLoS One (50) | Prospective, single-centre, Spain | 30, 63% | 64 yrs | 38% | Hospitalized for COVID-19 pneumonia and DD >1,000 ng/mL | Enoxaparin 40 mg daily: 27 (90%) | Elevated DD (>1,000 ng/ml) | 15% | Age, DD, platelet count, C-reactive protein |
| Helms et al., Intensive Care Medicine, preprint version (51) | Study of prospective cohort of consecutive patients, multi-centre, France | 150, 81% | 63 yrs | 100% | COVID-19 pneumonia, admission to ICU | LMWH: prophylactic dose: 105 (70%); therapeutic dose: 45 (30%) | Clinical suspicion or rapid rise in DD | 18% | Not studied |
| Longchamp et al., Res Pract Thromb Haemost (52) | Retrospective, single-centre, France | 25, 64% | 68 yrs | 100% | COVID-19 pneumonia, admission to ICU | 24/25 (96%) patients were prescribed TP: UFH or enoxaparin at standard prophylactic dose | Lower-limb CCUS was systematically performed in all patients between days 5 and 10 after admission to the ICU. CTPA performed for clinical suspicion | 32% | Not studied |
| Middeldorp et al., J Thromb Haemost, version preprint (53) | Retrospective study of cohort of consecutive patients, single-centre, Netherlands | 198, 66% | 61 yrs | 37% | Hospitalized for probable or confirmed COVID-19 | All with nadroparin: <100 kg: 2,850/12 h; ≥100 kg: 5,700/12 h | CTPA for clinical suspicion; CCUS by randomized selection | 17%. Accumulated incidence 14 days of 34% | UCI |
| Llitjos et al., J Thromb Haemost (54) | Retrospective study of cohort of consecutive patients, multi-centre, France | 26, 77% | 68 yrs | 100% | COVID-19, admission to ICU | Heparin: prophylactic dose: 18 (69%); therapeutic dose: 8 (31%) | CCUS in all patients (day 1-3 and day 7). Study for PE if there is clinical suspicion | 54% | Anticoagulation at prophylactic vs. therapeutic doses |
| Lodigiani et al., Thromb Res (55) | Retrospective study of cohort of consecutive patients, single-centre, Italy | 388, 68% | 66 yrs | 16% | Hospitalized for confirmed COVID-19 | TP in all patients in ICU and in 75% of those in a hospital ward | Clinical suspicion or rapid rise in DD | 7.7%. Accumulated incidence 21% | Not studied |
| Thomas et al., Thromb Res (56) | Retrospective, single-centre, United Kingdom | 63, 69% | 59 yrs | 100% | COVID-19, admission to ICU | All with Dalteparin adjusted to weight and renal function | Clinical suspicion | 9.5%. Accumulated incidence 27% | Not studied |
| Poissy et al., Circulation (57) | Retrospective, single-centre, France | 107, unspecified | Unspecified | 100% | COVID-19, admission to ICU | Antithrombotic prophylaxis with LMWH or UFH, with no specified dose or percentage of use in the complete cohort | Clinical suspicion due to respiratory and/or acute hemodynamic deterioration | 20.6%. Accumulated incidence at 15 days of 20.4% | DD, activity of factor VIII, levels of VWF |
| Bompard et al., Eur Respir J (58) | Retrospective, multi-centre, France | 135, 70% | 64 yrs | 18% | COVID-19 with pneumonia, with CTPA performed | TP with enoxaparin 40 mg/d in all hospitalized patients (53% of total) | Clinical suspicion and/or elevated DD | 24% | DD, ICU, MV |
| Demelos et al., Thromb Res (59) | Prospective observational, single-centre, Spain | 156, 65% | 68 yrs | 10% transferred from ICU | Hospitalized for COVID-19 ≥2 days, >18 years, DD >1,000 ng/mL | TP with enoxaparin 40 mg/d or bemiparin 3,500 UI/d in 153 patients (98%) | CCUS in all patients | 15%. All as DVT: 1 proximal DVT proximal and 22 distal DVT | DD |
| Poyiadi et al., Radiology (60) | Retrospective observational, multi-centre, USA | 328, 46% | 61 yrs | 25% ICU | Confirmed COVID-19 (PCR of nasopharyngeal swab) and adequate CTPA | Not studied | CTPA in all patients | 22% | BMI >30 kg/m2, DD ×6 times ULN, history |
| Mouhat et al., Eur Respir J (61) | Retrospective, observational, single-centre, France | 162, 67% | 66 yrs | 42% ICU | Hospitalized for COVID-19 and CTPA performed for severe disease (SpO2 <94% in room air or BR >29/min) | Anticoagulants in 87% (preventive dose in 74%, therapeutic doses in 13%): LMWH in 85%; UFH in 8%; oral anticoagulant: 7% | All included patients underwent a CTPA for clinical signs of severe disease. | 27% | DD >2,590 ng/mL. Lack of any anticoagulant therapy |
aPTT, activated partial thromboplastin time; BMI, body mass index; CCUS, compression Doppler ultrasound; BR, breathing rate; COVID-19, coronavirus disease 2019; CTPA, computed tomography pulmonary angiogram; DD, D-dimer; DVT, deep venous thrombosis; ICU, intensive care unit; LMWH, low molecular weight heparin; MV, mechanical ventilation; PE, pulmonary embolism; PT, prothrombin time; RCP, polymerase chain reaction; SpO2, oxygen saturation; TP, thromboprophylaxis; UFH, unfractionated heparin; ULN, upper limit of normal; USA, United States of America; VTE, venous thromboembolism; VWF, von Willebrand factor.