Table 2.

The 2020 case-control retrospective studies comparing risk factors for thrombosis development in hospitalized patients with severe COVID-19 (controls) versus hospitalized patients with both severe infection and DVT or ATE (cases). VTE: venous thromboembolism, ATE: arterial thromboembolism, WBCs: white blood cells, INR: international from Nappi et al. [81], Metabolites, 25 May 2021; 11(6):341.

Authors	Total SARS-CoV-2 + Hospitalized Patients	VTE, ATE Cases	Risk Factors More Present in Cases (p < 0.05)	Risk Factors Similar in Cases and Controls (p > 0.05)	Conclusions
Stoneham et al., 2020 [82]	208	21	High WBCs, high D-dimer, high INR.	APTT ratio, fibrinogen.	Comorbidities were not associated with a higher risk of thrombosis. Monitoring of D-dimer and anti-factor Xa levels may be relevant for management.
Zuo et al., 2020 [83]	44	11	High calprotectin, markers of NETs (myeloperoxidase-DNA complexes) high D-dimer, high platelets.	Troponins, WBCs.	There was a significant difference between peak D-dimer, calprotectin and cell free DNA levels between the populations.
Zhang et al., 2020 [84]	143	66	High WBCs, older age, low oxygenation index, high rate of cardiac injury, CURB-65 score 3 to 5, Padua score ≥ 4, high D-dimer.	Platelets count.	COVID-19 is suspected to cause an additional risk factor for DVT in hospitalized patients.
Planquette et al., 2020 [85]	1042	59	High CRP, fibrinogen, d-dimer. IMV.	Comorbidities: BMI, previous VTE, ATE, cancer, hypertension, cardiovascular diseases.	No higher prevalence for VTE risk factors in cases group compared to both cases and control was found. Altered coagulation parameters were found.
Trimaille et al., 2020 [86]	289	49	High Improve score, high WBCs, d-dimer, low haemoglobin at discharge.	Padua score of 4 or more, CRP-	Lack of thromboprophylaxis is a major determinant of VTE in non-ICU COVID-19 patients. Comorbidities were not found to affect the event occurrence.
Shah et al., 2020 [87]	187	81	High troponins, ferritin, d-dimer.	Platelets count, WBCs, thromboelastography parameters.	Elevated D-dimer, ferritin, troponin and white cell count at ICU admission may reflect undiagnosed altered coagulation and be used to identify patients for CTPA.
Kolielat et al., 2020 [88]	117	18	High d-dimer, fibrinogen, ferritin.	WBCs, platelets, troponins, Il-6.	Elevated d-dimer and a less elevated fibrinogen are associated with DVT despite conventional thromboprophylactic treatment.
Kampuori et al., 2020 [89]	443	41	High d-dimer, positive Wells criteria, bilateral infiltrates on X-rays or CT scan, mechanical ventilation.	Wbcs, platelets, CRP, Padua score, Geneva score.	The combination of Wells ≥ 2 score and D−dimer ≥ 3000 ng/L is a good predictor of VTE at admission. Hospitalization in the ICU and especially mechanical ventilation were associated with VTE occurrence. The combination of Wells’ score with the D-dimer value at admission can be a useful tool to guide empiric anticoagulation therapy.