Association between D-dimer level and chest CT severity score in patients with SARS-COV-2 pneumonia

The elevated level of D-dimer and its relationship with poor outcomes in SARS-COV-2 pneumonia patients have been demonstrated. In addition to a hypercoagulable state, D-dimer is also a biomarker of inflammation. We investigated the relationship between D-dimer level and chest computed tomography (CT) severity score, which could reflect the severity of inflammation in SARS-COV-2 pneumonia patients. We retrospectively enrolled 86 consecutive SARS-COV-2 pneumonia patients. CT severity scores were computed to quantify the overall lung involvement. The D-dimer level among CT score tertiles and the association of the D-dimer level with CT score were analyzed. Our results showed that the median D-dimer level was 0.70 mg/L (IQR 0.35-1.76). 42 patients (48.8%) had D-dimer levels above the median level. The D-dimer levels were significantly different across CT score tertiles (0.37 mg/l [IQR 0.31-0.87], 0.66 mg/l [IQR 0.39-1.43], 1.83 mg/l [IQR 0.85-4.41], P < 0.001). The natural logarithm of the D-dimer level was significantly associated with the CT score (r_s = 0.586, P < 0.001). In conclusion, the D-dimer level may be associated with the severity of inflammation of SARS-COV-2 pneumonia prior to coagulopathy/thrombosis. This could be an additional explanation for the mechanism of the relationship between elevated D-dimer level and higher mortality.