Lung function of patients hospitalized with COVID-19 at 45 days after hospital discharge: first report of a prospective multicenter study in Brazil

Because SARS-CoV-2 infection can severely affect the lungs and persistent functional changes can occur after severe disease, we aimed to determine lung function parameters of COVID-19 patients at 45 days after hospital discharge and compare changes according to the severity of the disease. This was a prospective descriptive analytical multicenter study. The participants were allocated into three groups: ward admission (WA) group; ICU admission not on mechanical ventilation (ICU/MV-) group; and ICU admission on MV (ICU/MV+) group. Lung volumes, DLco, MIP, MEP, and six-minute walk distance (6MWD) were measured 45 days after discharge. The sample comprised 242 patients (mean age = 59.4 ± 14.8 years; 52.1% of males), and 232 (96%) had altered lung function. In the total cohort, restrictive disorder was observed in 96%, as well as reductions in DLco (in 21.2% of the patients), FEV1/FVC (in 39.7%), and PEmax (in 95.8%), with no differences between the groups. Comparing the groups, the ICU/MV+ group had reduced DLco in 50% of the patients (p < 0.001) and a lower mean 6MWD % of the predicted value (p = 0.013). Oxygen desaturation in the six-minute walk test was observed in 32.3% of the cohort and was less frequent in the IE group. This is the first South American study involving severe COVID-19 survivors whose lung function was assessed 45 days after hospital discharge. Changes were frequent, especially in those on MV, which highlights the importance of lung function evaluation after severe COVID-19.