Does Follow-up D-Dimer Level Help in Predicting Oxygenation Status, Ventilatory Support Requirement, Lung Fibrosis, and Thromboembolic Events in Coronavirus Disease 2019 Pneumonia? A Prospective Observational Study in a Tertiary Care Setting in India

INTRODUCTION: Coronavirus disease 2019 (COVID-19) pneumonia is a heterogeneous disease with variable effects on lung parenchyma, airways, and vasculature, leading to long-term effects on lung functions. MATERIALS AND METHODS: This multicentric, prospective, observational, and interventional 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 the 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 CT severity were key observations. In selected cases, we have performed lower limb venous Doppler and computed tomography (CT) pulmonary angiography to rule out deep-vein thrombosis (DVT) or pulmonary thromboembolism (PTE) respectively. Statistical analysis is performed by using Chi-square test. OBSERVATIONS AND ANALYSIS: Age (<50 and >50 years) and gender (male vs. female) has a significant association with D-dimer level (P < 0.00001 and P < 0.010, respectively). CT severity score at the entry point with the D-dimer level has a significant correlation (P < 0.00001). The D-dimer level has a significant association with the duration of illness before hospitalization (P < 0.00001). Comorbidities have a significant association with D-dimer levels (P < 0.00001). D-dimer level has a significant association with oxygen saturation (P < 0.00001). BIPAP/NIV requirement has a significant association with the 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 as 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 has documented a very crucial role in COVID-19 pneumonia in predicting the severity of illness and assessing response to treatment during hospitalization, and follow-up titers have a significant role in step-up or step-down interventions in a critical care setting.