Pulmonary fibrosis after severe COVID-19 pneumonia: preliminary results of a 12-month follow-up study: a prospective cohort study

Abstract

BACKGROUND: After suffering from COVID-19, it is unclear whether recovered patients will have long-term health consequences. Early studies, with short follow-up time, suggest a reduction in pulmonary function, exercise capacity and quality of life in these patients. Additionally, some studies indicate that recovered patients, alike SARS and MERS, may develop pulmonary fibrosis. However, if these will be persistent over the years is uncertain. PURPOSE: The aim of this study is to determine the long-term health consequences with a longer follow-up time and to determine the incidence, the impact, and the risk factors of pulmonary fibrosis in patients after severe COVID-19 pneumonia. METHODS: This prospective cohort study includes 108 patients hospitalized in Girona with severe COVID-19 pneumonia diagnosis. Pulmonary function test, 6 minutes walking test, Saint George’s Respiratory Questionnaire, laboratory tests, chest X-ray, HRCT, lung ultrasound and transthoracic echocardiogram were performed at 1, 3 and 6 months after hospital discharge. Medical visit and exams at 12 months after discharge are pending, therefore, we present preliminary results. HRCT findings were analysed for parenchymal abnormalities, and patients were divided into two groups, A and B (with and without pulmonary fibrosis respectively). RESULTS: A total of 108 patients (74 men, 34 women; mean age  SD 60,95  13,70) were included. Dyspnea at 6 months after discharge was persistent in 53,9% of the patients. Impaired DLCO % predicted was found in 51,92% of the patients, being average diffusion capacity lower in patients with pulmonary fibrosis (71,25  18,73) than in patients without pulmonary fibrosis (80,53  15,65) (p=0,008). In 35,6% of the patients, pulmonary diffusion normalized at 6 months. Distance walked in 6 minutes improves 44,3m from 3 to 6 months (p=0,001). Saint George’s total score improves from 3 to 6 months (median [IQR] 19,52% [7,50-34,51] vs 16,16% [5,50-30,31]) (p=0,022). Pulmonary fibrosis was observed in 43,4% of the patients. Patients over 60 years old have 2,04 higher risk (95%CI 1,37 – 3,04) of developing pulmonary fibrosis than patients under 60 years old. Patients with pulmonary fibrosis, had during hospital stay, a higher peak LDH (p=0,034) and a lower lymphocytes count (p=0,001) than patients without pulmonary fibrosis. CONCLUSIONS: Hospitalized patients with severe COVID-19 pneumonia are at risk of developing long-term health consequences, including pulmonary fibrosis. Patients with evidence of fibrosis had worse pulmonary diffusion and worse exercise function, although this was not expressed in a reduction in quality of life. Patients aged 60 or more have a higher risk of pulmonary fibrosis