Presence and Evolution of Radiological Changes at 6 and 12 Months After COVID-19 Pneumonia and Their Risk Factors

<i>Background and Objectives</i>: The pulmonary sequelae of COVID-19 and their evolution are of interest to the scientific community. We aimed to determine the radiological changes at 6 and 12 months after COVID-19 pneumonia, its evolution and its risk factors. <i>Materials and Methods</i>: This retrospective longitudinal study included adults admitted for COVID-19 pneumonia from 1 March 2020 to 30 April 2021 who had a high-resolution computed tomography (HRCT) scan at 6 months and 12 months after hospital discharge. The primary outcome was the appearance of radiological abnormalities on HRCT and the number of lung segments affected by them at 6 and 12 months, while the main explanatory variables were about the disease course, analytical parameters and treatment. <i>Results</i>: This study included n = 108 patients, with a mean age of 64 years. There was a decrease in the percentage of patients presenting parenchymal (93.5% to 88.9%, <i>p</i> < 0.001) and reticular (63% to 62%, <i>p</i> < 0.001) patterns on HRCT at 12 months compared to 6, and an increase in those presenting a fibrotic pattern (62% to 63.9%, <i>p</i> < 0.001). Ground-glass opacities were the most frequent radiological change at 6 and 12 months (91.7% and 87%, respectively). There was a significant reduction in the total number of lung segments with ground-glass opacities (445 to 382, <i>p</i> < 0.001) and consolidation (158 to 136, <i>p</i> = 0.019) and an increase in those with bronchiectasis (66 to 80, <i>p</i> = 0.033) between the two moments. After multivariate analysis, high-flow oxygen therapy (HFOT), highest ferritin levels, hypertension and ≥71 years showed an association with the development of subpleural parenchymal bands, consolidation, bronchiectasis and septal thickening at 6 and 12 months. <i>Conclusions</i>: Parenchymal patterns seem to be more frequent than reticular and fibrotic patterns after COVID-19 pneumonia. The fibrotic pattern was the only one that worsened significantly over time, with bronchiectasis being the only change that increased at 12 months. Older age, hypertension, the need for HFOT, and high levels of ferritin may be directly associated with worse radiological outcomes after COVID-19 pneumonia.