Usefulness of GDF-15 as a biomarker of respiratory worsening in COVID-19 patients

Introduction: Grown Differentiation Factor-15 (GDF-15), also known as Macrophage Inhibitory cytokine-1 (MIC-1), is a Transforming Growth Factor (TGF)-β superfamily member secreted in response to pro-inflammatory mediators and oxidative stress and associates with inflammation and cellular damage. Aim and Objectives: to study the role of GDF-15 as a risk factor in patients with SARS-CoV-2 pneumonia admitted to hospital. Methods: 81 patients with COVID-19 and 20 healthy controls (HC) were included. GDF-15 was quantified by ELISA (R&D Systems) and compared to other inflammatory and respiratory parameters at admission. Results: We found higher levels of GDF-15 in COVID-19 patients in comparison with HC: 2042 (1396-3054) vs. 582 (370.8-807.6) pg/ml; p<0.0001. GDF-15 levels were higher in patients with low oxygen saturation (SaO2) (p=0.004) and with low SaO2/inspired fraction of oxygen (SaFi) ratio, (p=0.003). Differences in PCR, DD and ferritin values were observed when segregating according to SaO2 but not when segregating according to SaFi. A positive correlation between GDF-15 levels and PCR (p<0.001), ferritin (p=0.011), D-dimer (DD) (p=0.003) IL-6 (p<0.001) was found. Conclusions: GDF-15 levels are elevated in COVID-19 patients in comparison with HC. Those patients with respiratory worsening (SaFi<300) had the highest levels of GDF-15, but no differences in PCR, DD or ferritin. So, GDF-15 could be a good biomarker of respiratory deterioration to be used in clinical practice.