Utility of the Enhanced Liver Fibrosis score as a blood biomarker of pulmonary fibrosis secondary to SARS-CoV-2 pneumonia

Introduction: SARS-CoV-2 pneumonia can lead to several sequelae, among them, pulmonary fibrosis. The Enhanced Liver Fibrosis (ELF) score is a panel of serum markers of liver fibrosis. We aimed to describe the utility of the ELF score as a biomarker of pulmonary fibrosis secondary to COVID-19 pneumonia. Methods: Chest computed tomography (CT) scan, lung function tests (LFT) and blood analysis were obtained at three months after discharge. Data were analysed according to ELF scores and posteriorly divided into ELF tertiles. Results: One hundred twenty-nine patients were recruited; of these, 85.7% presented bilateral pneumonia at diagnosis of SARS-CoV2 infection. At 3 months after discharge, CT scan was available in 123 patients, 73 (59.3%) of whom presented parenchymal lung abnormalities (PLA) and LFT showed impairment in 28 (22.7%) patients. Globally, the most frequent PLA was ground glass opacities (50%), followed by bronchial thickening (26.8%), reticular pattern (19.5%), consolidation (10.5%) and air bronchogram sign (7.3%). Radiological findings were only significant in the higher tertile of ELF, with a reticular pattern as the predominant PLA (p = 0.002). Moreover, patients with both PLA and LFT impairment, presented a trend towards higher levels of ELF compared with patients with only PLA or LFT impairment, or no impairment (9.9 (0.7) vs 9.6 (0.8), 9.1 (1.1) and 9.3 (0.7); p = 0.054). Conclusion: Patients with both PLA and LFT alteration at 3 months after SARS-CoV-2 pneumonia had higher ELF scores. The ELF score may be useful to identify patients with risk of fibrotic changes after SARS-CoV-2 pneumonia.