Evaluation of lung findings after 12 months and 18-24 months of patients with COVİD-19 pneumonia by computed tomography

In December 2019, a novel coronavirus originating from bats and capable of infecting humans was identified in the city of Wuhan in Hubei province, People's Republic of China [1]. The disease caused by this virus was officially named "Coronavirus Disease 2019 (COVID-19)" by the World Health Organization (WHO), and it was declared a pandemic on March 11, 2020 [2]. Coronaviruses are viruses that affect the respiratory system in both humans and animals. Human-to-human transmission is recognized as the major mode of transmission for COVID-19 [3]. The clinical manifestations of COVID-19 infection constitute a systemic disease with evolving symptoms [4]. The lungs are the most commonly affected organs, with symptoms ranging from mild upper respiratory tract signs to severe acute respiratory distress syndrome. While long-term COVID affects various organs potentially, the attention is particularly drawn to lung damage, especially due to pneumonia leading to fibrosis [5][6]. There is a correlation between the extent of residual lesions in the lungs during the early period of COVID-19 pneumonia and the severity of acute lung involvement. Extensive residual bands can impact the lung's functional capacity in later stages of life. Therefore, long-term follow-up studies assessing sequelae in individuals who have survived COVID-19 are needed to improve prognosis and survival. Chest CT plays a significant role in the diagnosis, monitoring, and staging of pneumonia. Our study investigated lung CT findings at an average of 12 months and 18-24 months after COVID-19 pneumonia in patients who had recovered from COVID-19 pneumonia and those who had primary lung or extrapulmonary systemic disease at the time of diagnosis. Archived images of patients who presented to our hospital between March 1, 2020, and December 31, 2022, with proven COVID-19 pneumonia based on RT-PCR testing and compatible lung involvement on the initial lung CT scan, and who underwent repeat lung CT scans for various reasons (disease follow-up, nodule tracking, and other reasons) at an average of 12 months and 18-24 months, were retrospectively evaluated. The main study group consisted of 208 patients in the post-12-month group and 169 patients in the post-18-24-month control group. The severity score of COVID-19 pneumonia at the time of initial diagnosis was determined using the chest CT severity score applied by Xun Ding and colleagues. The CT severity score was assigned on a scale of 0-5 for each lung lobe based on the extent of involvement of lesions compatible with COVID-19 pneumonia at the time of initial diagnosis (0 points: no infiltration; 1 point: <5% infiltration; 2 points: 5-25% infiltration; 3 points: 25-50% infiltration; 4 points: 50-75% infiltration; 5 points: >75% infiltration) and scored between 0-25 [7]. Subsequently, the statistical relationship between the CT severity score of COVID-19 pneumonia at the time of initial diagnosis and the lung findings at an average of 12 months and 18-24 months after COVID-19 pneumonia, as well as complete recovery status, was investigated, taking into account the patients' age, gender, concomitant lung diseases, smoking history, diabetes mellitus, cardiovascular disease, lung cancer, and the presence of other systemic chronic diseases affecting the lungs. Changes occurring at an average of 12 months and 18-24 months after the acute COVID-19 pneumonia attack were categorized as complete recovery, non-fibrotic changes (ground-glass opacities, consolidation, nodules/masses, bands, reticulation), and fibrotic sequel changes (traction bronchiectasis, bronchiolectasis, honeycombing). According to the evaluation results, high-score COVID-19 pneumonia was observed in 69.2% of patients at the average 12-month follow-up CT, 60.7% in diabetic patients, 55.8% in patients with hypertension and/or cardiovascular disease, 72.4% in patients with both diabetes and hypertension, and 52.4% in individuals over 50 years of age, indicating a higher rate of non-fibrotic and fibrotic changes after COVID-19 pneumonia. At the average 18-24-month follow-up CT, high-score COVID-19 pneumonia was observed in 70.8% of patients, 63.6% in diabetic patients, 58% in patients with hypertension and cardiovascular disease, 81.8% in patients with both diabetes and hypertension, and 54.5% in individuals over 50 years of age, again indicating a higher rate of non-fibrotic and fibrotic changes after COVID-19 pneumonia. Therefore, we recommend longer clinical and radiological follow-up programs for individuals with high CT scores of COVID-19 pneumonia at the time of initial diagnosis, those with diabetes who have experienced COVID-19 pneumonia, those with hypertension and/or cardiovascular disease, those with both diabetes and hypertension, and individuals over 50 years of age. Keywords: COVID-19, Post-COVID lung changes, Computed tomography.