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Reporting of D-dimer data in COVID-19: some confusion and potential for misinformation
Emmanuel J Favaloro1,2,3, Jecko Thachil4
1Department of Haematology, Institute of Clinical Pathology and Medical Research (ICPMR), NSW Health Pathology, Westmead Hospital, Westmead, NSW 2145, Australia.
Insights
Elevated D-dimer levels are linked to COVID-19 severity. However, inconsistent reporting units (DDU vs. FEU) and missing data in studies can lead to misinterpretation of D-dimer results.
Area of Science:
- Biochemistry
- Clinical Medicine
- Infectious Diseases
Background:
- Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, is a global pandemic.
- Elevated D-dimer levels have been consistently associated with COVID-19 severity.
Purpose of the Study:
- To evaluate the reporting consistency of D-dimer assays in COVID-19 research.
- To identify potential sources of misinterpretation in D-dimer data due to variable reporting units and missing information.
Main Methods:
- A PubMed search was conducted to identify recent studies reporting D-dimer levels in COVID-19 patients.
- Analysis focused on the completeness and clarity of reporting regarding D-dimer assay manufacturers, units (DDU vs. FEU), and normal cut-off values.
Main Results:
- Most publications lacked details on D-dimer assay manufacturers and products.
- A significant number of studies did not specify whether D-dimer values were reported in D-dimer units (DDU) or fibrinogen equivalent units (FEU), which differ by approximately two-fold.
- Nearly half of the studies failed to report normal cut-off values, and some omitted numerical findings or units entirely.
- At least four reporting errors were identified across 21 reviewed papers, highlighting issues with units like mg/L or μg/mL.
Conclusions:
- Inconsistent reporting of D-dimer assays in COVID-19 research poses a risk of data misinterpretation.
- Harmonizing D-dimer assays to a single, standardized unit of measurement is feasible and necessary for reliable clinical interpretation and research synthesis.
Abstract:
Coronavirus disease 2019 (COVID-19) represents a new pandemic caused by severe acute respiratory syndrome virus coronavirus 2 (SARS-CoV-2). A previous pooled analysis clearly identified elevated D-dimer levels as being associated with severity of COVID-19. Since then, several other studies have provided clearer support for this initial evidence. However, potentially under-recognized by those reporting on D-dimer is the considerable variation in reporting units for D-dimer, and thus also the potential for misreporting of D-dimer data based on poor or incomplete reporting. A PubMed search was used to identify recent papers reporting on D-dimers in COVID-19-based studies. We report that: (1) most publications did not identify either the manufacturer or D-dimer product used; (2) most did not identify whether D-dimer values were reported as D-dimer units (DDU) or fibrinogen equivalent units (FEU) (~2 × differences); (3) nearly half did not identify normal cut-off values; (4) some did not report numerical findings or units for D-dimer; (5) where reported, most identified units as either mg/L or μg/mL; (6) we identified at least four errors in reporting from 21 papers. It may not be possible to truly standardize D-dimer assays, but it should be feasible to harmonize D-dimer assays to a single unit of measurement.
