Quantitative CT lung alterations and lung function in COVID-19 associated ARDS: 1-year follow-up

Introduction: COVID-19 pneumonia often causes long term radiological and functional lung alterations. Aims and objectives: Primary endpoint of our retrospective study was to evaluate the frequency and the extension after 1 year from the discharge of CT alterations (conventional and quantitative study) in the lungs of patients (pts) admitted to Vimercate Hospital for COVID-19 associated ARDS (CARDS). Secondarily, alterations in pulmonary function tests (PFTs) and 6 minute walking distance (6MWD) were investigated. Methods: 66 pts with CARDS entered the study and no one had previous chronic lung disease. Volumetric data were measured with Synapse 3D software and were compared with 20 healthy subjects of the same age. Categorical data were expressed as frequencies and percentages. Continuous variables were represented using median values. Multivariate logistic regression was performed for every category of data. Statistical significance was considered for p-value <0.05. Results: At 1-year follow-up only 5/66 pts (7.6%) showed a normal CT pattern. Conventional CT patterns were mostly ground-glass opacities, reticulations, subpleurical curves, traction bronchiectasis and fibrotic-like alterations. Quantitative analysis pointed out that the median lung volume of pts was significantly lower than that of the control group (p=0.011). The median compromised lung volume (VCo), including emphysema, interstitial impairment and consolidation was significantly higher in CARDS than in the control group (p≤0.001). DLCO, TLC and 6MWD were found to be negatively correlated with VCo. Conclusions: Our study highlights the need of a longer radiological and functional follow-up post-CARDS.