LAUSR

INTODUCTION: Impairment in pulmonary function tests and radiological abnormalities are a major concern in COVID-19 survivors. Our aim is to evaluate functional respiratory parameters, changes in chest CT, and correlation with peripheral blood biomarkers involved in lung fibrosis at two and six months after SARS-CoV-2 pneumonia METHODS: COVID-FIBROTIC (clinicaltrials.gov NCT04409275) is a multicenter prospective observational cohort study aimed to evaluate discharged patients. Pulmonary function tests, circulating serum biomarkers, chest radiography and chest CT were performed at outpatient visits. RESULTS: In total, 313, aged 61.12±12.26 years, out of 481 included patients were available. The proportion of patients with DLCO<80% was 54.6% and 47% at 60 and 180 days. Associated factors with diffusion impairment at 6 months were female sex (OR: 2.97, 95%CI 1.74 – 5.06, p=0.001), age (OR: 1.03, 95% CI: 1.01 – 1.05, p=0.005), and peak RALE score (OR: 1.22, 95% CI 1.06 – 1.40, p=0.005). Patients with altered lung diffusion showed higher levels of MMP-7 (11.54±8.96 vs 6.71±4.25, p=0.001), and periostin (1.11±0.07 vs 0.84±0.40, p=0.001). 226 patients underwent CT scan, of whom 149 (66%) had radiological sequelae of COVID-19. In severe patients, 68.35% had ground glass opacities and 38.46% had parenchymal bands. Early fibrotic changes were associated with higher levels of MMP7 (13.20±9.20 vs 7.92±6.32, p=0.001), MMP1 (10.40±8.21 vs 6.97±8.89, p=0.023), and periostin (1.36±0.93 vs 0.87±0.39, p=0.001). CONCLUSION: Almost half of patients with moderate or severe COVID-19 pneumonia had impaired pulmonary diffusion six months after discharge. Severe patients showed fibrotic lesions in CT scan and elevated serum biomarkers involved in pulmonary fibrosis.