Residual lung abnormalities after 12 months of COVID19 hospitalization: A brazilian multicenter study

Patients hospitalized due to hypoxemic COVID19 have a higher risk of residual fibrotic pulmonary sequelae. During follow-up, studies have demonstrated decreased lung function, especially reduced DLCO. <bold>Objective:</bold> To evaluate pulmonary function tests (PFTs) after 12 months of COVID19 hospitalization to identify lung sequelae and the risk factors for low DLCO. <bold>Methods:</bold> Observational, prospective, multicenter study of COVID-19 hospitalized patients between Mar,20-Nov,21. Patients underwent PFTs and 6-minute walking test(6MWT) after 12months of symptom onset. Results:708 patients were included, and 285 were re-evaluated after 12months. 55% were male, 58±12years, and 45% in ICU. 185 performed spirometry and 118 lung volumes/DLCO: 25% had FVC≤80%pred, 31% TLC≤80%pred, 49% DLCO≤80%pred. In the 6MWT (n=190) mean distance was 448±96m and 33% had desaturation ≥4points. Patients with DLCO≤80%pred were older (p<0.001),but had no differences in hospitalization severity. In PFTs, patients with DLCO≤80%pred had lower FVC%pred(85±14vs94±14;p<0.001), TLC%pred(80±14vs91±14;p<0.001),KCO%pred(86±19vs99±15;p<0,001),VA/TLC(0.87±0.27vs0.99±0.18;p=0,012),and peak SpO2 in 6MWT(94±5vs96±3;p=0.046) comparing to DLCO>80%pred. In the multivariate logistic analysis, DLCO≤80%pred were related to age ≥60years [1.48-9.89;p=0.006] and FVC≤80%pred [1.29–8.80;p=0.013]. Conclusion:After 12 months of follow-up, there was an improvement in PFTs, however almost 50% persisted with low DLCO. The reduced DLCO, VA and KCO associated with preserved VA/TLC suggest a fibrosing sequelae profile. Older patients with restrictive ventilatory patterns had a higher risk of reduced DLCO and need to be continued follow-up.