correlation between initial lung involvement on ct scan, assessed by total severity score, and pulmonary outcomes after three months in patients with severe covid-19

background: patients with severe covid-19 experience various respiratory complications, which can have potential long-termeffects.objectives: this study investigates the long-term pulmonary consequences of severe covid-19 and their relationship with theseverity of lung involvement.methods: all patients who survived severe covid-19 in the icu were selected for the study. a radiologist reviewed the chest ctscans, and patients were categorized based on their total severity score (tss) into two groups: group a (tss ≤ 7) and group b (tss> 7). patients were followed up after three months with a chest ct scan, spirometry, spo2 measurement, and a dyspnea scoreassessment.results: the mean age was 54.69 ± 12.51 for group a and 55.31 ± 12.73 for group b. groups a and b had 23 (46.9%) and 39 (39.4%)female patients, respectively. patients in group b had significantly lower spo2 and a prolonged length of hospitalization. groupb also experienced more severe dyspnea and reduced lung function, as observed in spirometry during the three-month followup. the total severity score decreased significantly after three months in all patients (from 14.42 ± 5.90 to 6.68 ± 4.79; p < 0.001). after logistic regression analysis, non-invasive ventilation was independently associated with a higher tss (or = 0.45 when comparing group a to group b; p = 0.028).conclusions: the lungs are the most affected organ by covid-19, making it crucial to investigate the effects of the virus on pulmonary function. our study showed that patients with higher tss experienced greater reductions in lung function during the three-month follow-up. additionally, the use of non-invasive ventilation was independently associated with a higher tss in severe covid-19 cases.