Factors associated with fibrotic-like pattern on thorax CT after COVID-19 pneumonia

This study aimed to investigate whether coronavirus disease-2019 (COVID-19) leads to impaired pulmonary function, fibrotic-like abnormalities or psychological symptoms six months after discharge.

This study involves 162 laboratory-confirmed patients with COVID-19 who were diagnosed in Ankara University Faculty of Medicine, Department of Chest Diseases from February 1, 2021 to July 1, 2023. All patients were diagnosed with COVID-19 pneumonia by thorax computed tomography (CT). Patients who applied to the outpatient clinic six months after COVID-19 treatment were included in the study. A total of 133 patients underwent thorax CT scan, pulmonary function tests, six minutes walking test simultaneously. Radiographic patterns were categorized into two groups (normal/non-fibrotic and fibrotic-like). Group A had 66 patients who either had no fibrotic or non-fibrotic changes, and 67 patients who had fibrotic-like changes were categorized as group B.

Mean age of the study subjects was 55.95 ± 12.42 years, and 75 (56.4%) patients were male. Overall, median diffusing capacity of the lungs for carbon monoxide (DLCO) % predicted measured as 73.5% [IQR 61-88]. DLCO and six-minute walking distance were significantly lower in the fibroticlike pattern group (p< 0.001, p= 0.014, respectively). Reduced DLCO in patients with fibrotic-like pattern after six months was common. Presence of ground-glass opacities, reticulations and traction bronchiectasis correlated strongly with reduced diffusing capacity (r= -0.190 p= 0.043, r -0.305 p= 0.001, r -0.404 p< 0.001, respectively). We demonstrated that smoking history and intensive care unit (ICU) admisson during COVID-19 pneumonia were independent risk factors for fibrotic-like radiographic abnormalities.

Residual abnormalities resembling fibrosis were notably prevalent, particularly among severely ill patients, and impaired lung diffusion persisted in some individuals even six months post-discharge. Post-COVID-19 lung sequelae can persist and progress after hospital discharge, suggesting airways involvement and formation of new fibrotic-like lesions, mainly in patients who had been in the ICU and had smoking history.