Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors
Filter by Categories
Case Report
Case Series
Editorial
Letter to Editor
Original Article
Review Article
Technical Note
Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors
Filter by Categories
Case Report
Case Series
Editorial
Letter to Editor
Original Article
Review Article
Technical Note
Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors
Filter by Categories
Case Report
Case Series
Editorial
Letter to Editor
Original Article
Review Article
Technical Note
View/Download PDF

Translate this page into:

Original Article
1 (
1
); 31-37
doi:
10.25259/GJHSR_11_2023

Role of D-Dimer in assessing severity, monitoring, and predicating outcome in COVID-19 pneumonia: A single center study

Department of Pulmonary Medicine, MIMSR Medical College, Venkatesh Chest Hospital, Latur, Maharashtra, India
Department of Pathology, MIMSR Medical College, Latur, Maharashtra, India
Department of Internal Medicine, NIMS Medical College, Jaipur, Rajasthan, India
Corresponding author: Shital Patil, Department of Pulmonary Medicine, MIMSR Medical College, Venkatesh Chest Hospital, Latur, Maharashtra, India. drsvpatil1980@gmail.com
Licence
This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

How to cite this article: Patil S, Khule S, Toshniwal S. Role of D-Dimer in assessing severity, monitoring, and predicating outcome in COVID-19 pneumonia: A single center study. Glob J Health Sci Res 2023;1:31-7.

Abstract

Objectives:

Robust data are available regarding role of D-dimer in analyzing coagulation status in pulmonary embolisms and deep vein thrombosis. As thrombogenic nature of coronavirus disease 2019 (COVID-19) has been evolved in this pandemic, we have studied its role in predicting disease severity, correlation with durations of illness and oxygenation status, and ventilatory support requirement with prediction of deep vein thrombosis and pulmonary embolism in these cases.

Materials and Methods:

Prospective, observational follow-up study, included 2000 COVID-19 cases confirmed with reverse transcription–polymerase chain reaction. All cases were assessed with high-resolution computed tomography (HRCT) thorax, oxygen saturation, inflammatory marker as D-Dimer at entry point and follow-up. Age, gender, comorbidity, and use of bilevel-positive airway pressure (BIPAP)/non-invasive ventilation (NIV) and outcome as with or without lung fibrosis were key observations. In selected cases, lower limb venous Doppler and computed tomography (CT) pulmonary angiography to rule out deep vein thrombosis or pulmonary thromboembolism. Statistical analysis is done using Chi-square test.

Results:

CT severity score at entry point with D-Dimer titer has significant correlation (P < 0.00001). Age (<50 and >50 years) and gender (male vs. female) have significant association with D-Dimer level (P < 0.00001) and (P < 0.010), respectively. D-Dimer titer has significant association with duration of illness before hospitalization (P < 0.00001). Comorbidities have significant association with D-Dimer level (P < 0.00001). D-Dimer titer has significant association with oxygen saturation (P < 0.00001). BIPAP/NIV requirement has significant association with D-Dimer level (P < 0.00001). Timing of BIPAP/NIV requirement during hospitalization has significant association with D-Dimer level (P < 0.00001). Follow-up D-Dimer titer during hospitalization, as compared normal and abnormal to entry point level has significant association with post-COVID lung fibrosis, deep vein thrombosis and pulmonary thromboembolism (P < 0.00001).

Conclusion:

D-Dimer has documented very crucial role in COVID-19 pneumonia in predicting severity of illness, ventilatory support requirement and course in critical care setting. D-Dimer follow-up titer has documented role in predicting lung fibrosis and deep vein thrombosis and pulmonary embolism. D-Dimer serial titers have documented significant role in step-up or step-down interventions in critical care setting.

Keywords

Coronavirus disease 2019 pneumonia
D-Dimer
lung fibrosis
Deep vein thrombosis
Pulmonary embolism
Inflammatory marker

INTRODUCTION

The current pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), originally emerged from China, has documented 274,628,461 confirmed cases and 5,358,978 deaths globally, and 34,752,164 confirmed cases 478,007 deaths in India.[1] The International Federation of Clinical Chemistry and Laboratory Medicine Task Force on COVID-19 has been established to synthesize up-to-date information on the epidemiology, pathogenesis, and laboratory diagnosis and monitoring of COVID-19, as well as to develop practical recommendations on the use of molecular, serological, and biochemical tests in disease diagnosis and management.[2,3]

COVID-19, the pandemic disease caused by infection with the novel virus, SARS-CoV-2 can now be added to the already extensive list of conditions that may be associated with elevated D-dimer. The discovery that D-dimer may be elevated in COVID-19 was first reported by physicians in Wuhan, China where the epidemic started. A study of 191 patients with COVID-19, who were hospitalized in Wuhan during January 2020 at the outset of the pandemic, revealed that D-dimer was elevated in many of these patients and the magnitude of the elevation was greatest in those who did not survive.[4,5]

Fibrin degradation products are a highly heterogeneous group of soluble fragments that appear in the circulation as a result of two simultaneous physiological processes: (1) Coagulation, resulting in the conversion of soluble fibrinogen into insoluble stabilized fibrin by the enzymes thrombin and factor XIIIa, (2) Fibrinolysis, resulting in the dissolution of the fibrin clot by the enzyme plasmin. The D-dimer fragment is the terminal product of this process.[5] A number of subsequent studies conducted around the world have confirmed that D-dimer is elevated in those with severe COVID-19 and highest in those who are most critically ill and those who do not survive. Much COVID-19 research over the past months has been directed at understanding the significance of D-dimer elevation and the COVID-19 related coagulopathy that is presumed responsible for the elevation.[4,5]

D-dimer has been extensively investigated for the diagnosis, monitoring, and treatment of venous thromboembolism for which it is used routinely.[5,6] D-dimer levels are also elevated in conditions of chronic inflammation, such as active malignancy, rheumatoid arthritis, sickle cell disease, and asthma.[7] In the setting of COVID-19, D-dimer has been reported to be higher in subjects who are critically ill or those who expire.[4,8-11]

MATERIAL AND METHODS

Ethical approval

This study was approved by the Institutional Review Board/ Ethics Committee at Venkatesh Hospital and Critical Care Center Latur India and MIMSR Medical College Latur India, (Approval number: VCC/63-2020-2021; Approval date 09/08/2020).

Data source

Prospective, observational, 12 weeks follow-up study, conducted during July 2020–May 2021, in MIMSR Medical College Latur and Venkatesh Hospital Latur India, included 2000 COVID-19 cases confirmed with reverse transcription– polymerase chain reaction (RT-PCR), to find out role of D-Dimer in assessing severity, monitoring and predicating risk of deep vein thrombosis, pulmonary embolism, and post-COVID lung fibrosis in diagnosed COVID-19 pneumonia cases admitted in indoor unit. A total of 2000 cases were enrolled in study after IRB approval and written informed consent of all included cases were taken at respective centers of study in Venkatesh Hospital and MIMSR Medical College Latur.

Inclusion criteria

COVID-19 patients, confirmed with RT-PCR, above the age of 18 years, hospitalized in the study centers, including those with comorbidities irrespective of severity and oxygen saturation were included in the study.

Exclusion criteria

Those not willing to give consent, not able to perform D-Dimer and not willing to remain in follow-up, and cases that died during hospitalization or before 12 weeks of discharge from hospital were excluded from the study.

Methodology of CRP titer assessment: Immunoturbidimetry

Normal values: Normal values up to 6 mg/L.

All study cases were undergone following assessment before enrolling in study

COVID-19 RT-PCR test was performed on nasopharyngeal samples collected with all standard institutional infection control policies, if first test results were negative and radiological features clearly documenting pneumonia, we have repeated RT-PCR test and enrolled all cases with positive COVID-19 RT-PCR test. HRCT Thorax to assess severity of lung involvement as per COVID-19 Reporting and Data System,[12] and categorized as mild if score <7, moderated if score 8–15 and severe if score >15 or 15–25. Clinical assessment and routine biochemistry and hematological workup with viral inflammatory markers as C-reactive protein (CRP), Ferritin, lactate dehydrogenase, interleukin 6 (IL-6) titers, and D-Dimer in all cases. Entry point D-Dimer titer was utilized as an assessment tool of severity of illness with clinical parameters. If D-dimer analysis was normal at entry point, then D-Dimer titer was repeated on day of discharge from hospital or done during hospitalization if clinical course deteriorates. If D-dimer analysis was abnormal at entry point, we repeated it every 72 h as follow-up to assess severity, progression of illness and also titer utilized to assess response to medical treatment. Follow-up HRCT thorax was done after 12 weeks of discharge from hospital for analysis of post-COVID lung fibrosis in selected cases with abnormal D-Dimer titer at discharge and required BIPAP/NIV during hospitalization and cases required oxygen supplementation at home [Figure 1].

Figure 1:
Flow of the study.

Interpretation of results

Normal values: Normal values 70–470 mg/dL

  1. Normal: D-Dimer value up to 470 mg/L

  2. Positive: Value above 470 mg/dL

  3. Significant: Two-fold raised D-Dimer level

  4. Highly significant: Four-fold raised D-Dimer titer

  5. Follow up significance: Values raised or decreased in two-to-four-fold change.

Statistical analysis

The statistical analysis was done using Chi-square test in R-3.4 software. Significant values of χ2 were seen from probability table for different degree of freedom required. P value was considered significant if it was below 0.05 and highly significant in case if it was <0.001.

RESULTS: COVARIATES

In the present study, 2000 COVID-19 pneumonia cases confirmed by COVID-19 RT-PCR, males were 1300/2000 and females were 700/2000, age >50 were 1200 cases, and age <50 were 800 cases. Significant association in D-Dimer and COVID-19 pneumonia has been documented with variables such as age, gender, diabetes mellitus, ischemic heart disease (IHD), hypertension, chronic obstructive pulmonary disease (COPD), and obesity (P < 0.00001) [Table 1].

Table 1: Other variables and D-Dimer titer in COVID-19 pneumonia cases (n=2000).
COVID-19 RT-PCR positive (n=2000) D-Dimer titer normal (n=640) D-Dimer titer abnormal (n=1360) Analysis
Age>50 years (n=1200) 280 920 χ2=51.77
Age<50 years (n=800) 360 440 P<0.00001
Male gender (n=1300) 380 920 χ2=6.5
Female gender (n=700) 260 440 P<0.0100
Diabetes mellitus (n=1200) 300 900 χ2=33.77
Without diabetes (n=800) 340 460 P<0.00001
Hypertension (n=420) 320 100 χ2=238.55
Without hypertension (n=1580) 320 1260 P<0.00001
COPD (n=300) 200 100 χ2=97.46
Without COPD (n=1700) 440 1260 P<0.00001
IHD (n=400) 220 180 χ2=60.77
Without IHD (n=1600) 420 1180 P<0.00001
Obesity (n=320) 40 280 χ2=33.28
Without obesity (n=1680) 600 1080 P<0.00001

RT-PCR: Reverse transcription–polymerase chain reaction, COPD: Chronic obstructive pulmonary disease, IHD: Ischemic heart disease

Observations and analysis

Computed tomography (CT) severity score at entry point with D-Dimer titer has significant correlation in COVID-19 pneumonia cases (P < 0.00001) [Table 2]. D-Dimer titer has significant association with duration of illness (DOI) in COVID-19 pneumonia cases (P < 0.00001) [Table 3]. Significant association in D-Dimer and COIVD-19 pneumonia has been documented with variables such as age, gender, diabetes mellitus, IHD, Hypertension, COPD, and obesity (P < 0.00001) [Table 4]. D-Dimer titer has significant association with oxygen saturation in COVID1-19 pneumonia cases (P < 0.00001) [Table 4]. BIPAP/NIV requirement during course of COVID-19 pneumonia in critical care setting has significant association with D-Dimer level (P < 0.00001) [Table 5]. Timing of BIPAP/NIV requirement during course of COVID-19 pneumonia in critical care setting has significant association with D-Dimer level (P < 0.00001) [Table 6]. Follow-up D-Dimer titer during hospitalization as compared to entry point abnormal D-Dimer has significant association in post-COVID lung fibrosis (P < 0.00001) [Table 7]. Follow-up D-Dimer titer during hospitalization as compared to entry point normal D-Dimer has significant association in post-COVID lung fibrosis (P < 0.00001) [Table 8]. Follow-up D-Dimer titer during hospitalization as compared to entry point abnormal D-Dimer has significant association in presence of deep vein thrombosis (P < 0.00001) [Table 9]. Follow-up D-Dimer titer during hospitalization as compared to entry point normal D-Dimer has significant association with pulmonary thromboembolism (P < 0.00001) [Table 10].

Table 2: Correlation of CT severity (at entry point) and D-Dimer in COVID-19 cases (n=2000).
CT severity Normal D-Dimer (n=640) Abnormal D-Dimer titer (n=1360) Analysis
<8 score (n=600) 380 220 χ2=224.87
9–15 (n=600) 180 420 P<0.00001
>15 (n=800) 80 720

CT: Computed tomography

Table 3: DOI at entry point during hospitalization and D-Dimer titerin COVID-19 pneumonia cases (n=2000).
DOI Normal D-Dimer (n=640) Abnormal D-Dimer (n=1360) Analysis
<7 days (n=680) 60 620 Chi test
value 185.65
P<0.00001
8–15 days (n=920) 320 600
>15 days (n=400) 260 140

DOI: Duration of illness

Table 4: Oxygen saturation at entry point and D-Dimer titer in COVID-19 pneumonia cases (n=2000).
Oxygen saturation Normal D-Dimer titer (n=640) Abnormal D-Dimer titer (n=1360) Analysis
>90% (n=420) 220 200 Chi test
value 60.37
P<0.00001
75–90% (n=980) 300 680
<75% (n=600) 120 480
Table 5: Correlation of BIPAP use with D-Dimer titer in COVID-19 pneumonia cases (n=2000).
BIPAP/NIV Normal D-Dimer (n=640) Abnormal D-Dimer titer (n=1360) Analysis
BIPAP/NIV required (n=1200) 310 890 Chi test value 26.21
BIPAP/NIV not required (n=800) 330 470 P<0.00001
Table 6: BIPAP/NIV initiation time at entry point and D-Dimer titer in COVID-19 pneumonia cases (n=1200).
BIPAP used (n=1200) with duration of illness Abnormal D-Dimer (n=580) Four-fold raised D-Dimer (n=620) Analysis
Entry point <1 days (n=360) 220 140 χ2=31.30 P<0.00001
3–7 days (n=620) 300 320
After 7 days (n=220) 60 160
Table 7: Abnormal D-Dimer titer at entry point (n=1360) and follow-up and its correlation with post-COVID lung fibrosis.
Post-COVID COVID pneumonia fibrosis D-Dimer titer increased/abnormal at entry point (n=800) D-Dimer titer four-fold increased during follow up (n=560) Analysis
Pulmonary fibrosis present (n=420) 80 340 χ2=198.45 P<0.00001
Pulmonary fibrosis absent (n=940) 720 220
Table 8: Normal D-Dimer titer (n=640) at entry point and follow-up and its correlation with post-COVID lung fibrosis.
Post-COVID COVID pneumonia fibrosis D-Dimer titer normal at entry point and remained less than fourfold (n=240) D-Dimer titer four-fold increased during follow up (n=400) Analysis
Pulmonary fibrosis present (n=80) 10 70 χ2=12.19 P<0.00048
Pulmonary fibrosis absent (n=560) 230 330
Table 9: Abnormal D-Dimer titer at entry point (n=1360) and its correlation with follow-up titer with deep vein thrombosis.
DVT D-Dimer titer increased/abnormal at entry point (n=800) D-Dimer titer fourfold increased during follow up (n=560) Analysis
DVT present (n=420) 80 340 Chi test value 198.45 P<0.00001
DVT absent (n=940) 720 220

DVT: Deep vein thrombosis

Table 10: Normal D-Dimer titer (n=640) at entry point and its correlation with follow-up titer with PTE.
PTE D-Dimer normal at entry point and remained less than fourfold (n=240) D-Dimer titer fourfold increased during follow up (n=400)
PTE present (n=80) 10 70 Chi test value 12.19 P<0.00048
PTE absent (n=560) 230 330

PTE: Pulmonary thromboembolism

DISCUSSION

In the present study, CT severity score at entry point with D-Dimer titer has significant correlation in COVID-19 pneumonia cases, score <8, 8–15, and >15 documented normal and abnormal D-Dimer (P < 0.00001). We observed that CT severity is best visual assessment and indirect marker of inflammation which can be collaborated with D-dimer, and as CT severity score increases, D-Dimer titer also increases, which is a marker of coagulation abnormality. Numerous studies[13-19] have documented similar observation.

In the present study, D-Dimer titer has significant association with DOI in COVID-19 pneumonia cases, DOI <7 days, 8–15 days, and >15 days of onset of symptoms documented ormal and abnormal D-Dimer levels (P < 0.00001). As DOI in COVID-19 pneumonia increases, ongoing inflammation increases and having abnormal D-Dimer titer due to abnormal coagulation cascade stimulation. Studies by various author[14-20] have documented similar observation. We have also documented that; entry point abnormal D-Dimer with other inflammatory markers such as CRP and IL-6 with DOI more than a week or 7 days is predictor of prolonged hospital stay with requirement of ventilatory requirement in intensive care unit. Similar observation has been documented in various studies.[20-24]

In the present study, BIPAP/NIV requirement during course of COVID-19 pneumonia in critical care setting has significant association with D-Dimer level (P < 0.00001).

We have documented positive correlation with hypoxia and resulting in need of ventilatory support during hospitalization with abnormal D-Dimer level. Similarly, various authors[14,20-25] have observed that abnormal or high D-dimer is predictor of poor outcome and these patients require aggressive interventions such as BIPAP/NIV, mechanical ventilation, or ECMO in due course and persistent high level denotes higher chances of mortality.

In the present study, D-Dimer titer has significant association with oxygen saturation in COVID-19 pneumonia cases (P < 0.00001). We have documented positive correlation with hypoxia at entry point during hospitalization and abnormal D-Dimer titer which is similar to studies by various authors.[14,25] Low oxygen saturation or hypoxia is independent predictor of poor outcome in COVID-19 pneumonia, as hypoxia is trigger for deranged coagulation secondary to increase in hypoxia-inducible transcription factor which will increase D-Dimer level, numerous studies[20-24] have documented similar observation.

In the present study, timing of BIPAP/NIV requirement during course of COVID-19 pneumonia in critical care setting has significant association with D-Dimer titer (P<0.00001) We have documented positive correlation with hypoxia and resulting in need of ventilatory support during hospitalization with abnormal D-Dimer level. Cases with high D-dimer would have required BIPAP/NIV early as compared with normal to slightly raised D-Dimer level, which is in correlation with studies[14,25] documented similar observation.

In the present study, follow-up D-Dimer titer during hospitalization during hospitalization as compared to entry point abnormal D-Dimer has significant association in post-COVID lung fibrosis (P < 0.00001). Follow-up D-Dimer titer during hospitalization as compared to entry point abnormal D-Dimer has significant association in presence of deep vein thrombosis (P < 0.00001). We have observed that ongoing inflammation is the key for rise of D-Dimer titer irrespective of CT severity score as mild cases were also having significant rise in D-Dimer titer as compared to advanced CT severity, thus it will help in predicting progression of disease in due course during hospitalization and aggressive steps to be taken during management of these cases. Numerous studies[25-31] have documented similar risk of poor outcome and adverse lung outcome as increased D-Dimer is an indication of severe inflammatory response and resulted in lung fibrosis in follow-up of survivors of COVID-19pneumonia.

In the present study, follow-up D-Dimer titer during hospitalization as compared to entry point normal D-Dimer has significant association in post-COVID lung fibrosis (P < 0.00001). In this study, a small fraction of non-severe patients developed into severe cases in the first 2 weeks after symptom onset. Therefore, health care institutions should also pay close attention to the mild patients, identify progressor early, and provide appropriate treatment to reduce mortality. Follow-up D-Dimer titer during hospitalization as compared to entry point normal D-Dimer has significant association with pulmonary thromboembolism (P < 0.00001). Authors in various studies[14-17,20-25] have documented similar observation.

In the present study, age of patient, that is., <50 years and >50 years has significant association in COVID-19 cases with normal and abnormal D-Dimer titer (P < 0.00001). We have also documented that the gender of included cases has significant association with normal and abnormal D-Dimer titer in COVID-19 cases (P < 0.010). Studies by various authors[14-19,25-32] have documented similar observation.

In the present study, comorbidities as Diabetes mellitus, COPD, hypertension, IHD, and obesity have documented significant association in COVID-19 cases with normal and abnormal D-Dimer titer at entry point (P<0.00001). Numerous studies[14-19,25-32] have documented similar observation.

CONCLUSION

D-Dimer has documented very crucial role in COVID-19 pneumonia in predicting severity of illness, ventilatory support requirement and course in critical care setting. D-Dimer follow-up titer can help in predicting progression of COVID-19 pneumonia, and assessing risk of post-COVID lung fibrosis. D-Dimer serial titers have documented significant role in step-up or step-down interventions in critical care setting.

D-Dimer titer has significant associations with predicting progression of pneumonia, as proportionate number of pneumonia cases with mild variety on CT thorax and normal initial D-Dimer has progressed to critical course and we have documented follow-up titers has played crucial role with other inflammatory markers.

Correlating D-dimer with variables such as DOI, oxygenation status, and timing of BIPAP/NIV at entry point is important to have satisfactory treatment outcome. D-Dimer follow-up titer has documented role in predicting lung fibrosis and deep vein thrombosis and pulmonary embolism.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent.

Conflicts of interest

There are no conflicts of interest.

Financial support and sponsorship

Nil.

References

  1. , . The critical role of laboratory medicine during coronavirus disease 2019 (COVID-19) and other viral outbreaks. Clin Chem Lab Med. 2020;58:1063-9.
    [CrossRef] [PubMed] [Google Scholar]
  2. , , , , , , et al. Molecular, serological, and biochemical diagnosis and monitoring of COVID-19: IFCC taskforce evaluation of the latest evidence. Clin Chem Lab Med. 2020;58:1037-52.
    [CrossRef] [PubMed] [Google Scholar]
  3. , , , , , , et al. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: A retrospective cohort study. Lancet. 2020;395:1054-62.
    [CrossRef] [PubMed] [Google Scholar]
  4. . Validation, calibration, and specificity of quantitative D-dimer assays. Semin Vasc Med. 2005;5:315-20.
    [CrossRef] [PubMed] [Google Scholar]
  5. . D-dimer in venous thromboembolism. N Engl J Med. 2003;349:1203-4.
    [CrossRef] [PubMed] [Google Scholar]
  6. , , , , , , et al. Factors associated with positive D-dimer results in patients evaluated for pulmonary embolism. Acad Emerg Med. 2010;17:589-97.
    [CrossRef] [PubMed] [Google Scholar]
  7. , , , . Coagulation abnormalities and thrombosis in patients with COVID-19. Lancet Haematol. 2020;7:e438-40.
    [CrossRef] [PubMed] [Google Scholar]
  8. , , , , , , et al. Elevated D-dimer levels are associated with increased risk of mortality in COVID-19: A systematic review and meta-analysis. Cardiol Rev. 2020;28:295-302.
    [CrossRef] [PubMed] [Google Scholar]
  9. , , , . Abnormal coagulation parameters are associated with poor prognosis in patients with novel coronavirus pneumonia. J Thromb Haemost. 2020;18:844-7.
    [CrossRef] [PubMed] [Google Scholar]
  10. , , , , , , et al. Clinical characteristics of 113 deceased patients with coronavirus disease 2019: Retrospective study. BMJ. 2020;368:m1091.
    [CrossRef] [PubMed] [Google Scholar]
  11. , . Imaging pulmonary inflammation. J Nucl Med. 2016;57:1764-70.
    [CrossRef] [PubMed] [Google Scholar]
  12. , , , , , , et al. CO-RADS: A categorical CT assessment scheme for patients suspected of having COVID-19-definition and evaluation. Radiology. 2020;296:E97-104.
    [CrossRef] [PubMed] [Google Scholar]
  13. , , , , . Association between D-Dimer titer and chest CT severity score in patients with SARS-COV-2 pneumonia. Sci Rep. 2021;11:11636.
    [CrossRef] [PubMed] [Google Scholar]
  14. , , , , , , et al. Correlation between chest CT severity scores and the clinical parameters of adult patients with COVID-19Pneumonia. Radiol Res Pract. 2021;2021:6697677.
    [CrossRef] [PubMed] [Google Scholar]
  15. . Correlation of chest CT severity score with D-dimer levels in patients with COVID-19. Eur Heart J. 2021;42:1285.
    [CrossRef] [Google Scholar]
  16. , , , , , , et al. Immune parameters and COVID-19 infection-associations with clinical severity and disease prognosis. Front Cell Infect Microbiol. 2020;10:364.
    [CrossRef] [PubMed] [Google Scholar]
  17. , , . CT characteristics and laboratory findings of COVID-19 pneumonia in relation to patient outcome. Egypt J Radiol Nucl Med. 2021;52:28.
    [CrossRef] [Google Scholar]
  18. , , , , , , et al. Prevalence and outcomes of D-dimer elevation in hospitalised patients with COVID-19. Arterioscler Thromb Vasc Biol. 2020;40:2539-47.
    [CrossRef] [PubMed] [Google Scholar]
  19. . Corona (COVID-19) time musings: Our involvement in COVID-19pathogenesis, diagnosis, treatment and vaccine planning. Autoimmun Rev. 2020;19:102538.
    [CrossRef] [PubMed] [Google Scholar]
  20. , , , , , , et al. Clinical characteristics of coronavirus disease 2019 in China. N Engl J Med. 2020;382:1708-20.
    [CrossRef] [PubMed] [Google Scholar]
  21. , , , , , , et al. Clinical characteristics and imaging manifestations of the 2019 novel coronavirus disease (COVID-19): A multi-center study in Wenzhou city, Zhejiang, China. J Infect. 2020;80:388-93.
    [CrossRef] [PubMed] [Google Scholar]
  22. , , , , , , et al. The correlation between viral clearance and biochemical outcomes of 94 COVID-19 infected discharged patients. Inflamm Res. 2020;69:599-606.
    [CrossRef] [PubMed] [Google Scholar]
  23. , , , . The diagnostic and predictive role of NLR, d-NLR and PLR in COVID-19patients. Int Immunopharmacol. 2020;84:106504.
    [CrossRef] [PubMed] [Google Scholar]
  24. , , , , , , et al. Laboratory markers versus Ct severity score in predicting mortality in Covid 19. Eur J Mol Clin Med. 2021;7:1824-31.
    [Google Scholar]
  25. , , , , , , et al. D-dimer levels on admission to predict in-hospital mortality in patients with Covid-19. J Thromb Haemost. 2020;18:1324-9.
    [CrossRef] [PubMed] [Google Scholar]
  26. , , , . D-Dimer titeris a useful predictor for mortality in patients with COVID-19: Analysis of 483 cases. Diabetes Metab Syndr Clin Res Rev. 2020;14:2245-9.
    [CrossRef] [PubMed] [Google Scholar]
  27. , , , , , , et al. Admission D-dimer levels, D-dimer trends, and outcomes in COVID-19. Thromb Res. 2020;196:99-105.
    [CrossRef] [PubMed] [Google Scholar]
  28. , , , , , , et al. Elevated levels of D-dimer in patients with COVID-19: Prognosis value. Pan Afr Med J. 2020;35
    [CrossRef] [PubMed] [Google Scholar]
  29. , , , , , et al. Biomarkers and short-term prognosis in COVID-19. Biomarkers. 2021;26:119-26.
    [CrossRef] [PubMed] [Google Scholar]
  30. , , , , , , et al. The poor prognosis and influencing factors of high D-dimer levels for COVID-19 patients. Sci Rep. 2021;11:1830.
    [CrossRef] [PubMed] [Google Scholar]
  31. , , , , , , et al. D-dimer as a biomarker for assessment of COVID-19prognosis: D-dimer levels on admission and its role in predicting disease outcome in hospitalized patients with COVID-19. PLoS One. 2021;16:e0256744.
    [CrossRef] [PubMed] [Google Scholar]
Show Sections