Elevated d-Dimer Levels Are Associated With Increased Risk of Mortality in Coronavirus Disease 2019: 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 2 prospective) with a total of 3682 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 fourfold higher in patients with positive d-dimer versus negative d-dimer (risk ratio, 4.11; 95% CI, 2.48-6.84; P < 0.001) and the risk of developing severe disease was twofold higher in patients with positive d-dimer levels versus 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.