D-dimer: A Marker of Severity in COVID-19

Abstract

Introduction: The ever-growing number of COVID-19 patients stresses upon the need to identify effective yet readily available predictors of disease severity to ensure better clinical outcomes. D-dimer is a fibrin specific degradation product derived by enzymatic action of plasmin on factor XIIIa cross-linked fibrin. It serves as an ideal marker for activation of coagulation and fibrinolytic pathways. Identification of coagulopathy as an important complication in COVID-19 patients has brought to focus D-dimer as a possible predictor of clinical severity in patients. Aim: In this study, we analysed the role of D-dimer levels in assessing the clinical severity of the COVID-19 patients. Materials and Methods: We enrolled 217 in-patients of Tirunelveli Medical College in this single centre observational study and classified them into asymptomatic, mild, moderate and severe according to “Clinical Management Protocol: COVID 19”, by the Ministry of Health and Family Welfare and Director General of Health Services. D-dimer was estimated in the separated plasma, using latex based assay using semi-automated coagulation analyser. Data were presented as percentages for categorical variables and median±Inter Quartile Range (IQR) for continuous variables. Chi-square test was used to compare the D-dimer values between symptomatic and asymptomatic groups. A value of p<0.05 was considered statistically significant. Results: Among the 217 cases, 88.9% were asymptomatic cases, 8.8% presented with mild clinical severity and 2.3% had moderate clinical presentation. In our study population, the Mean±SD and Median±IQR of D-dimer values (in ng/mL) were 223.4±230.6 and 157.0±187.7, respectively. The mean D-dimer value was found to increase as the category of our study group ascended from asymptomatic patients to mild and moderate clinical cases. It was noted that 91.1% of the cases who had D-dimer values <500 ng/mL were asymptomatic. Also, the odds of patients with high levels of D-dimer being clinically symptomatic was 5.5 times more than the odds of patients with D-dimer levels <500 ng/mL. Conclusion: Elevation of D-dimer levels associated with the severity of clinical course of patients infected with SARS CoV-2 when compared to patients with mild or asymptomatic clinical presentations.