Objective: To assess the association between D-dimer and clinical outcomes in adults with COVID-19. Methods: We reviewed published articles and preprints from MEDLINE, Cochrane Library, Cornell Open Access Publication (COAP), MedRxiv, and BioRxiv databases. We included cohort studies on the association between D-dimer and the outcomes of thromboembolism, mortality, and worsening severity among hospitalized adults with COVID-19. Results: We found 25 observational studies on the association between D-dimer and the outcomes of thromboembolism, mortality, or worsening severity. There was an increased risk of thromboembolism (OR 5.61 [95% CI 3.97, 7.94]) with higher D-dimer levels across different COVID-19 severities. D-dimer levels are associated with higher in-hospital mortality (OR 5.57 [95% CI 2.74, 11.31]) and worsening severity manifesting as critical illness (OR 1.91 [95% CI 1.05, 3.48] to 2.58 [95% CI 1.57, 4.24]), disease progression (HR 2.846 [95% CI 2.10, 3.85]), or need for mechanical ventilation (HR 3.28 [95% CI 1.07, 10.10]). However, some methodological flaws, such as incomplete laboratory or follow-up data and concern on varied D-dimer cut-offs and definitions of worsening disease, raise some uncertainty in the widespread use of D-dimer as a prognostic marker. Conclusion A higher D-dimer value is associated with worse clinical outcomes among hospitalized adults with COVID-19 and may be a useful prognostic indicator.
COVID-19