The role of angiopoietin-2 and surfactant protein-D levels in SARS-CoV-2-related lung injury: A prospective, observational, cohort study.

Introduction: Coronavirus disease-2019 (COVID-19) is a respiratory disease whose clinical manifestation ranges from asymptomatic to severe respiratory failure. The purpose of this study was to investigate the place of serum surfactant-D (SP-D) and angiopoetin-2 (Ang-2) levels in predicting severity of disease in patients diagnosed with COVID-19.

Methods: Sixty-four patients diagnosed with COVID-19 between September 2020 and February 2021, 50 patients diagnosed with community-acquired pneumonia and a 50-member healthy control group were included in the study. Plasma samples and clinical data were collected within 72 h after admission, during hospital stay. Serum SP-D and Ang-2 concentrations were measured using the enzyme-linked immunosorbent assay.

Results: SP-D and Ang-2 levels were significantly higher in the mild-moderate pneumonia and severe/critical patient groups compared to the asymptomatic and noncomplicated COVID-19 patients (p < 0.001 for all groups). Serum SP-D and Ang-2 levels of severe-critical COVID-19 patients were significantly higher than CAP patients (p < 0.001). Powerful correlation was present between clinical severity of COVID-19 and SP-D and Ang-2 levels (r = 0.885 p < 0.001 and r = 0.913 p < 0.001, respectively). Cut-off values of 37.7 ng/ml (AUC = 0.763, p < 0.001, 95% confidence interval [CI] = 0.667-0.860) for SP-D and 4208.3 pg/ml (AUC = 0.659, p = 0.004, 95% CI = 0.554-0.763) for Ang-2 were identified as predictors of COVID-19 disease at receiver operating characteristic curve analysis.

Conclusion: SP-D and Ang-2 are predictive factors in differentiating COVID-19 patients and determining severity of disease. These data may be important for the initiation of treatment in the early stage of the disease in patients with COVID-19.