The results of the checklist [7] are described in Table 1.
Selection of sources of evidence
A total of 238 articles (MEDLINE, 155; CENTRAL, 1; ClinicalTrial.gov, 79; WHO-ICTRP, 11; PROSPERO, 7) regarding the treatment of coagulopathy in COVID-19 patients were identified, and 38 studies were selected according to the title and abstract for further full-text review after the removal of duplicates (Fig. 1). Among them, seven articles fulfilled the inclusion criteria, and one article was assessed after reviewing the references of another study. Thus, eight studies were analyzed in the scoping review[8-15]. The results of the literature search strategy are described in Table 2. There is no previous scoping review on this topic.
Characteristics of the sources of evidence
The author, status, publication or registration data, location, study design, patient conditions, interventions, and outcomes of all the included studies are summarized in Map 1.
Status, publication or registration data, and location
Regarding the status of the studies, seven studies have been published and two clinical studies are ongoing. The first study was published in March 2020 [8], followed by studies in April (n = 4) [9-12] and May (n = 1) [13]. The ongoing studies were registered in March [14] and April [15]. The studies were conducted in China (n = 2) [8, 12], France (n = 2) [11, 13], Ireland (n = 1) [9], the Netherlands (n = 1) [10], Canada (n = 1) [15], and the USA (n = 1) [14].
Study design
The study design included case series (n = 3) [9, 10, 13], retrospective cohort studies (n = 3) [8, 11, 12], and randomized control trials (RCTs) (n = 2) [14, 15]. None of the studies followed case report, case-control or prospective cohort studies.
Patients’ conditions
Coagulopathy was assessed using several scales, such as the International Society on Thrombosis and Hemostasis (ISTH) DIC score [16](n = 3) [9, 13, 14], Japanese Association for Acute Medicine (JAAM) DIC score [17] (n = 1) [13], sepsis-induced coagulopathy (SIC) DIC score [18] (n = 2) [8, 13], D-dimer level (n = 6) [8, 9, 11-13, 15] and other blood coagulation tests (n = 2) [10, 11]. Seven studies described patient severity [8-14], of which one study [13] used the simplified acute physiology score (SAPS) II [19]. The DIC diagnostic criteria released from the Japanese Society on Thrombosis and Hemostasis (JSTH) DIC score [20] or Japanese Ministry of Health and Welfare (JMHW) DIC score [21] were not used.
Anticoagulants
The anticoagulants therapies used in the studies were a prophylactic dose of unfractionated heparin (UFH) (n = 3, mainly 1000 – 15000 U/day) [8, 11-13], therapeutic dose of UFH (n = 3, detail of dose not reported) [11, 13, 15], prophylactic dose of low molecular weight heparin (LMWH) (n = 7, mainly enoxaparin 40 - 60 mg/day) [8-14], therapeutic dose of LMWH (n = 4, mainly enoxaparin 1 - 1.5 mg/kg/day) [11, 13-15], and the other (n = 1) [9].
Outcomes
The survival of patients, incidence of venous thromboembolism (VTE), incidence of MOF, results of blood coagulation tests, and other outcomes were assessed in 7 [8-12, 14, 15], five [10, 11, 13-15], one [11], one [15], and three studies [11, 14, 15], respectively. The side effects caused by the anticoagulant therapy were reported in one study [13].
Results of the individual sources of evidence
Tang et al [8]
Data and location: In March 2020 from China
Study design: a retrospective cohort study
Patients: 449 severe COVID-19 patients
Coagulopathy and severity condition: Ninety-seven out of 449 patients (21.6%) met the SIC criteria (total score ≥ 4). Plasma levels of D-dimer exceeding 3.0 µg/mL were noted in 161 patients (32.2%).
Interventions: Ninety-nine (22.0%) patients received heparin treatment for at least 7 days, and 94 of those patients received LMWH (enoxaparin 40-60 mg/day) and 5 patients received UFH (10000 - 15000 U/day).
Comparisons: 350 patients did not receive any anticoagulant.
Outcome: No statistically significant difference in 28-day mortality was found between patients who received heparin and those who did not receive heparin (30.3% vs. 29.7%, p = 0.910). The 28-day mortality of heparin users was lower than that of nonusers in patients with severe coagulopathy with an SIC score ≥4 (40.0% vs. 64.2%, p = 0.029) and D-dimer values >3.0 µg/mL (32.8% vs. 52.4%, p = 0.017).
Note: The number of heparin users and nonusers with SIC scores ≥4 and D-dimer values >3.0 µg/mL, respectively, were not reported. Neither therapy-related side effects nor the study design was reported.
Fogarty et al [9]
Data and location: April 2020 from Ireland
Study design: case series
Patients: 83 hospitalized COVID-19 patients
Coagulopathy and severity condition: The median and quantile D-dimer levels were 732 ng/ml (200 - 10,000 ng/ml), and none of the patients met the diagnostic criteria of DIC as defined according to the ISTH DIC score on admission.
Interventions: The dose of LMWH was based on a prophylactic dose and adjusted according to body weight and renal function (enoxaparin 20 mg OD if < 50 kg; enoxaparin 40 mg OD if 50-100 kg; 40 mg BD if 101-150 kg; 60 mg BD if >150 kg). Eight patients had renal impairment on admission and were therefore treated with enoxaparin 20 mg OD. Four patients were on therapeutic anticoagulation (2 patients on apixaban, 1 on edoxaban and 1 on warfarin).
Outcome: 50 patients (60.2%) had fully recovered and were discharged from the hospital without requiring ICU admission, while 20 remained in the hospital and 13 had died. Among the patients, 23 were transferred to the ICU during treatment.
Note: The study design was reported as a cohort, but this study did not compare the clinical outcomes among anticoagulants. Side effects were not reported.
Klok et al [10]
Data and location: April 2020 from the Netherlands
Study design: case series in multiple centers
Patients: 184 patients admitted to the ICU
Coagulopathy and severity condition: Prolongation of the prothrombin time (PT) > 3 seconds or activated partial thromboplastin time (APTT) > 5 seconds was noted in 70 patients.
Interventions: The standard dose of nadroparin differed between hospitals: 2850 IU subcutaneous injection (sc) per day or 5700 IU per day if bodyweight > 100 kg; 5700 IU per day; 5700 IU sc twice daily; 2850 IU sc per day or 5700 IU per day if bodyweight > 100 kg; and 5700 IU sc per day.
Outcome: Twenty-two patients were discharged alive (12%), 139 (76%) were still in the ICU, and 23 died (13%). The number of patients with the composite outcome was 31, and ultrasonography confirmed DVT in 3 patients and arterial thrombotic events in 3 patients. Pulmonary embolism (n = 25) was the most frequent thrombotic complication. Coagulopathy defined as above was an independent predictor of thrombotic complications (adjusted HR 4.1, 95% CI 1.9 - 9.1).
Note: Neither therapy-related side effects nor the study design was reported.
Llitjos et al [11]
Data and location: April 2020 from France
Study design: retrospective cohort study
Patients: 26 patients with severe COVID-19 received mechanical ventilation.
Coagulopathy and severity condition: The median and quantile SOFA score and concentrations of D-dimers and fibrinogen were 2.5 (2 - 3.2), 2330 ng/mL (1495 - 3165) and 7.1 g/L (6.9 - 8.3) in the therapeutic anticoagulation group and 3.5 (3 - 5), 1750 ng/mL (1245 - 2850) and 6.8 g/L (6.4 - 7.3) in the prophylactic anticoagulation group, respectively.
Interventions: Eight patients (31%) were treated with the prophylactic dose of the anticoagulant such as LMWH or UFH. The details of the prophylactic doses were not reported.
Comparisons: Eighteen patients (69%) were treated with the therapeutic dose of anticoagulant such as LMWH or UFH. The details of the therapeutic doses were not reported.
Outcome: The overall rate of VTE at day 7 after ICU admission was 69%. The proportion of VTE was significantly higher in patients treated with prophylactic anticoagulation than in the therapeutic group (100% vs. 56%, respectively, p=0.03). The numbers of patients who developed ARDS, pulmonary embolism, acute kidney injury, and liver dysfunction or who died were 7, 0, 2, 1, and 1, respectively, in the prophylactic group and 14, 6, 7, 3, and 2 in the therapeutic group.
Note: Neither therapy-related side effects nor the study design was reported.
Yin et al [12]
Data and location: April 2020 from China
Study design: retrospective cohort study
Patients: hospitalized COVID-19 patients
Coagulopathy and severity condition: patients with D-dimer levels ≧ 3.0 µg/mL.
Interventions: Ninety-four patients received LMWH (enoxaparin 40 – 60 mg/day), 5 received UFH (10000 – 15000 U/day) for at least 7 days.
Comparisons: 350 received no anticoagulants.
Outcome: The 28-day mortality of heparin users was significantly lower than that of nonusers (32.8% vs. 52.4%, p = 0.017).
Note: Side effects were not reported.
Helms et al [13]
Data and location: May 2020 from France
study design: a case series
Patients: 150 COVID-19 ARDS patients admitted to the ICU
Coagulopathy and severity condition: The median quantile levels of D-dimer and fibrinogen were 2.27 mg/L (1.16 - 20) and 6.99 g/L (6.08 - 7.73), respectively. A total of 144 patients (96%) were diagnosed with non-JAAM-DIC (< 4 points), none of the patients were diagnosed with DIC by the ISTH criterion (< 5 points), and 22 patients (14.7%) had a positive SIC score. The median SAPS II score was 49 (37 – 64) points.
Interventions: The prophylactic dose was 4000 UI/day for LMWH or 5–8 U/kg/h for UFH. The therapeutic dose was not described.
Outcome: Sixty-four clinically relevant thrombotic complications were diagnosed, with pulmonary embolisms being the most frequent event (16.7%). The reported side effects included hematoma in 4 patients (2.7%).
Note: The study design was reported as a cohort; however, the outcomes were not reported based on anticoagulants, and the study was judged as a case series.
Usha et al [14]
Data and location: in April 2020 from the U.S.A.
study design: single-center, randomized, open-label study
Patients: 170 hospitalized COVID-19 patients
Coagulopathy and severity condition: ISTH Overt DIC scores ≥ 3.
Interventions: the prophylactic dose of enoxaparin (40 mg SC daily or 30 mg SC twice daily if BMI ≥40; standard of care arm).
Comparison: intermediate-dose enoxaparin (1 mg/kg sc daily or 0.5 mg/kg sc twice daily if BMI ≥ 40; intervention arm).
Outcome: the outcome measures were all-cause mortality, major bleeding, arterial thrombosis, venous thromboembolism, and ICU admission.
Note: ongoing
Sholzberg et al [15]
Data and location: in April 2020 from Canada
Study design: multicenter open-label randomized controlled trial
Patients: hospitalized patients with COVID-19
Coagulopathy and severity condition: D-dimer (≥ 2-fold of the upper limit of normal)
Interventions: therapeutic anticoagulation including the LMWH used in this study includes tinzaparin 175 U/kg once per day, enoxaparin 1.5 mg/kg once per day or 1 mg/kg twice per day or dalteparin 200 U/kg once per day or 100 U/kg twice per day. UFH will be administered using a bodyweight-based nomogram according to the center-specific institutional protocol.
Comparison: the standard care
Outcome: The primary outcome is the composite outcome of ICU admission, noninvasive positive pressure ventilation, invasive mechanical ventilation, or all-cause death up to 28 days.
Note: ongoing
Protocol versus overview
Our planned search strategy registered in protocol.io was compared with the final reported review methods. There was a difference between the study designs reported by original articles and those judged by our reviews. We chose to report the study design based on our judgment.