D-dimer in Coronavirus Disease 2019 pneumonia: A valuable inflammatory marker in predicting trends of systemic effects in addition to thromboembolic events! A single-center experience

Introduction: Robust data are available regarding the role of D-dimer as a marker of coagulation abnormality in infectious, inflammatory, and malignant process. Its role in predicting coagulation abnormality in the currently ongoing coronavirus disease 2019 (COVID-19) pandemic is evolving. In present we have studied its role in predicting severity, coagulation, and vascular abnormalities such as deep-vein thrombosis (DVT) and pulmonary thromboembolism (PTE). We have also studied the role of D-dimer in the prediction of final radiological outcome as post-COVID lung fibrosis in follow-up. Materials and Methods: Prospective, observational study included 1000 COVID-19 cases confirmed with reverse transcription polymerase chain reaction. All cases were assessed with high-resolution computed tomography thorax, oxygen saturation, inflammatory marker as D-dimer at entry point and follow-up. Age, gender, comorbidity, use of bilevel positive airway pressure/noninvasive ventilation (BiPAP/NIV), and outcome as with or without lung fibrosis as per computed tomography (CT) severity were key observations. In selected cases, we have performed lower limb venous Doppler and CT pulmonary angiography to rule out DVT or PTE respectively. Statistical analysis is done by using Chi-square test. Results: Age (<50 and >50 years) and gender (male vs. female) has significant association with D-dimer level (P < 0.00001) and (P < 0.010) respectively. CT severity score at entry point with D-dimer level has significant correlation (P < 0.00001). D-dimer level has significant association with duration of illness (DOI) before hospitalization (P < 0.00001). Comorbidities have a significant association with D-dimer level (P < 0.00001). D-dimer level has a significant association with oxygen saturation (P < 0.00001). BIPAP/NIV requirement has a significant association with D-dimer level (P < 0.00001). Timing of BIPAP/NIV requirement during hospitalization has a significant association with D-dimer level (P < 0.00001). Follow-up D-dimer titer during hospitalization compared to normal and abnormal to entry point level has a significant association with post-COVID lung fibrosis, DVT and PTE (P < 0.00001). Conclusions: D-dimer is an easily available, and universally acceptable inflammatory marker, which has documented a very crucial role in COVID-19 pneumonia in predicting the severity of illness, and assessing response to treatment during hospitalization. D-dimer has an important role during interventions in the intensive care unit, as follow-up titers have a significant role in step-up or step-down interventions in critical care settings. Correlating D-dimer with variables like DOI, oxygenation status, and timing of BIPAP/NIV at the entry point is important to have a satisfactory treatment outcome.