Table 1.

Brief literature review of the clinical laboratory coagulation indexes previously reported in coronavirus disease 2019 (COVID-19) patients.

Test (unit)	Target population or center/country	Consistency (with our results)	Included patients/main findings	Reference
PT (s)	Tianyou Hospital, Wuhan, China	✓	115 patients were included. The mean ± SD results for the PT test in critical and severe groups were 13.70 ± 3.38 and 12.14 ± 1.16 s, respectively.	(13)
	Jinyintan Hospital and Wuhan Pulmonary Hospital, China	✓	191 patients [survivors (n = 137), non-survivors (n = 54)] were studied. PTSurvivors = 11.4 s, PTnon-Survivors = 12.1 s (p = 0·0004) 7 (13%) of expired patients had PT ≥ 16, while only 4 (3%) of patients who survived had PT ≥ 16.	(14)
	Chongqing, China	✓	135 patients were recruited. The mean PT values for the critical and severe groups were 11.3 and 10.8 s, respectively (p = 0.011)	(15)
aPTT (s)	Tongji Hospital, Wuhan, China	✓	147 patients were enrolled. The mean aPTT results were 42.4 in expired patients(N = 35) and 40.6 in survivors (N = 112, p = 0.256)	(16)
	Tianyou Hospital, Wuhan, China	✓	115 patients were included. Critical group had higher aPTT results when compared with the severe and mild groups (36.98 ± 8.60, 36.47 ± 9.29, and 34.9 ± 9.17 s, respectively).	(13)
	Chongqing, China	✓	135 patients were recruited. The mean aPTT values for the critical and severe groups were 29.7 and 26.6 s, respectively (p = 0.011).	(15)
Fibrinogen	Renmin Hospital of Wuhan University	✓	94 patients were studied. 502 ± 153 mg/ml in COVID-19 patients compared to 290 ± 53 mg/ml in the control group (p < 0.001)	(17)
	Suzhou Hospital	✓	75 patients were enrolled. While the average fibrinogen levels in controls were 200–400 mg/ml, patients were reported to have significantly higher levels (430 ± 119 mg/ml, p < 0.05).	(18)
	Fuyang Second People’s Hospital	✓	43 patients were studied. The average fibrinogen levels in the severe group was 384 ± 100 mg/ml and in the mild group was 311 ± 083 mg/ml (p = 0.14).	(15)
Anti-lupus coagulant (s)	Hospitals in Liechtenstein and Switzerland	N/A	64 patients were studied. Higher total IgA and IgA anti-phospholipid antibodies were found in severe patients (p < 0.001).	(19)
	Lariboisière Hospital, Paris	✓	74 consecutive mechanically ventilated patients were enrolled. LAC was positive in 63 patients (85%). 23 out of 28 patients with thrombotic complications were positive.	(20)
	Tan Tock Seng Hospital, Singapore	✓	12 ICU patients with severe COVID-19 pneumonia were included. Lupus anticoagulants were present in 50% of patients.	(21)
Protein C (%)	R Adams Cowley Shock Trauma Center, Maryland, USA		10 critically ill patients were included, who were using mechanical lung ventilation. The mean protein C activity was 104 ± 40 (normal = 83%–168%).	(22)
	Tenon University Hospital, Paris, France		430 patients were included. Protein C activity was higher in conventional (mild) patients (97%, 79–113) than the worsening disease group (88%, 71–100).	(23)
	Tan Tock Seng Hospital, Singapore		12 ICU patients with severe COVID-19 pneumonia were included. The average activity of protein C was 77.5%.	(21)
Protein S (%)	Colentina University Hospital Bucharest, Romania	✓	91 patients were enrolled, of whom 21 (23.3%) died. 65% of the patients were reported to have decreased protein S activity. Death cases had lower protein S activity (median = 42% vs. 58%, p < 0.001).	(24)
	Tan Tock Seng Hospital, Singapore	✓	12 ICU patients with severe COVID-19 pneumonia were included. The average activity of protein S was 65.2%.	(21)
	Gregorio Marañon Hospital, Madrid, Spain	N/A	206 patients were enrolled. The average protein S activity in COVID-19 patients with thrombosis was 60.9 (46.3–69.4), while the mean activity in patients without thrombosis was 53.2 (42.1–66.9, p = 0.429).	(25)
ATIII (%)	Milan, Italy	✓	24 intubated patients were included. The mean antithrombin activity was slightly decreased [74 U/dl, reference range mean = 102 (82–122)].	(26)
	Tan Tock Seng Hospital, Singapore	✓	12 ICU patients with severe COVID-19 pneumonia were included. The average activity of ATIII was 84.4%.	(21)
	R Adams Cowley Shock Trauma Center, Maryland, USA	✓	10 critically ill patients were included, who were using mechanical lung ventilation. The mean ATIII activity was 84 (normal = 75%–135%).	(22)
D-dimer (μg/ml)	Tianyou Hospital of Wuhan, China	N/A	Classified 115 patients into four groups according to the disease severity. 18 out of 22 deceased patients had increased levels of D-dimer in the first lab test (3.47 ± 7.41 mg/l in expired patients compared to 0.87 ± 1.73 mg/l in discharged patients). The change in CT imaging was in correlation with the increase of the D-dimer levels.	(13)
	Jin Yin-tan Hospital, Wuhan, China	✓	41 patients were included (ICU patients: n = 13; no ICU care: n = 28). D-dimer levels on admission were higher in ICU patients (2.4 mg/L) than those in non-ICU patients (0.5 mg/L).	(27)
	Texas, USA	N/A	15,313 hospitalized patients >18 years old 285 were reported to have acute ischemic stroke, who had higher D-dimer levels at admission (1.42 vs. 0.94 µg/ml FEU, p < 0.001). Elevated D-dimer levels >5.15 µg/ml was shown to increase mortality nearly 3 times.	(28)
	Tianyou, Puren, and China Resources & WISCO General Hospitals, Wuhan, China	✓	1,114 patients with COVID-19 were included. The value 2.025 mg/L was determined as the optimal probability cutoff to predict death. The D-dimer levels of the expired patients were notably higher than those of surviving individuals. D-dimer levels of COVID-19 patients with DIC were higher when compared to those without DIC.	(29)
FDP	Tongji Hospital, Wuhan	✓	147 patients were enrolled. The mean FDP levels were 70.8 in expired patients (N = 35) and 4.8 g/L in survivors (N = 112, p < 0.001).	(16)
	Renmin Hospital of Wuhan University	✓	94 patients were studied. 33.83 ± 82.28 mg/L in COVID-19 patients compared to 1.55 ± 1.09 mg/L in healthy controls (p < 0.001)	(17)
	Tongji Hospital of Huazhong University, Wuhan	✓	183 patients were included, among them 21 patients expired. Significant increase in FDP levels between survivors and non-survivors [4.0 (4.0–4.3) vs. 7.6 μg/ml (4.0–23.4)]	(30)

PT, prothrombin time; aPTT, activated partial thromboplastin time; ATIII, antithrombin III; FDP, fibrin degradation product; LAC, lupus anticoagulant; N/A, not applicable; FEU, fibrinogen equivalent unit; DIC, disseminated intravascular coagulation.