This study seeks to determine the utility of D-dimer levels as a biomarker in determining disease severity and prognosis in COVID-19.

Clinical, imaging and laboratory data of 120 patients whose COVID-19 diagnosis based on RT-PCR were evaluated retrospectively. Clinically, the severity of COVID-19 was classified as noncomplicated or mild or severe pneumonia. Radiologically, the area of affected lungs compatible with viral pneumonia in each patient's computed tomography was classified as either 0–30% or ≥ 31% of the total lung area. The D-dimer values and laboratory data of patients with COVID-19 were compared with inpatient status, duration of hospitalization, and lung involvement during treatment and follow-up. To assess the predictive value of D-dimer, receiver operating characteristic (ROC) analysis was conducted.

D-dimer elevation (> 243 ng/ml) was detected in 63.3% (76/120) of the patients. The mean D-dimer value was calculated as 3144.50 ± 1709.4 ng/ml (1643–8548) for inpatients with severe pneumonia in the intensive care unit. D-Dimer values showed positive correlations with age, duration of stay, lung involvement, fibrinogen, neutrophil count, neutrophil lymphocyte ratio (NLR) and platelet lymphocyte ratio (PLR). When the threshold D-dimer value was 370 ng/ml in the ROC analysis, this value was calculated to have 77% specificity and 74% sensitivity for lung involvement in patients with COVID-19.

D-Dimer levels in patients with COVID-19 correlate with outcome, but further studies are needed to see how useful they are in determining prognosis.