Post-COVID-19 Interstitial Lung Disease: a new entity, what do we deal with?

Abstract

<b>Introduction:</b> In the post-acute phase, COVID-19 survivors may have persistent symptoms, lung function abnormalities and sequela lesions on thorax CT. This new entity is defined as post-COVID Interstitial Lung Disease (ILD) or a residual disease. <b>Aim:</b> To investigate the characteristics and clinical significance of post-COVID-19 ILD. <b>Methods:</b> Patients with persistent respiratory symptoms after recovery were evaluated by a team including two pulmonologists and a radiologist. Pulmonary function tests, 6-minute walking test, thorax HRCT were performed. Post-COVID ILD was defined as presence of all the followings: respiratory symptoms, hypoxemia, restrictive lung functions and interstitial changes on follow-up HRCT. <b>Results:</b> A total of 375 post-COVID-19 patients were evaluated on average 91 days after recovery and 262 of them were included. 17.9 % of the patients were non-hospitalized with mild COVID-19; 10.8 % of the patients had received high flow nasal oxygen, of 17.5 % had required non-invasive mechanical ventilation, of 8.8 % had been intubated. The most prevalent symptoms were dyspnoea, exercise intolerance and fatigue. The mean mMRC score was 1.82, oxygen saturation was 94.1, 6-minute walking distance was 374 meters. Pulmonary functions (percentage of mean predicted value ± SD) were as follows; FEV1:79±19, FVC: 73±19, FEV1/FVC: 87±9, DLCO: 64.5±21.8. On CT, GGOs, fibrotic bands, and a combination of them were detected. The mean CT score was 13.5. <b>Discussion:</b> The presence of symptoms and functional defects in addition to radiological parenchymal lesions requires the definition of this new entity is post-COVID-19 ILD which could be seen even in non-hospitalised patients with mild COVID-19.