Elevated D-Dimer Levels are Associated with Increased Risk of Mortality in COVID-19: A Systematic Review and Meta-Analysis.

The 2019 novel coronavirus, declared a pandemic, has infected 2.6 million people as of April 27, 2020, and has resulted in the death of 181,938 people. D-dimer is an important prognostic tool, is often elevated in patients with severe coronavirus disease-19 (COVID-19) infection and in those who suffered death. In this systematic review, we aimed to investigate the prognostic role of D-dimer in COVID-19-infected patients. We searched PubMed, Medline, Embase, Ovid, and Cochrane for studies reporting admission D-dimer levels in COVID-19 patients and its effect on mortality. Eighteen studies (16 retrospective and two prospective) with a total of 3,682 patients met the inclusion criteria. The pooled weighted mean difference (WMD) demonstrated significantly elevated D-dimer levels in patients who died versus those who survived (WMD 6.13 mg/L, 95% confidence interval [CI] 4.16 - 8.11, p <0.001). Similarly, the pooled mean D-dimer levels were significantly elevated in patients with severe COVID-19 infection (WMD 0.54 mg/L, 95% CI 0.28 - 0.80, p< 0.001). The risk of mortality was four-fold higher in patients with positive D-dimer vs. negative D-dimer (risk ratio 4.11, 95% CI 2.48 - 6.84, p< 0.001) and the risk of developing severe disease was two-fold higher in patients with positive D-dimer levels vs. negative D-dimer (risk ratio 2.04, 95% CI 1.34 - 3.11, p < 0.001). Our meta-analysis demonstrates that patients with COVID-19 infection presenting with elevated D-dimer levels have an increased risk of severe disease and mortality.