Long-Term Sequelae of severe COVID-19: Outpatient assessment of radiological and pulmonary function tests

OBJECTIVE: Identify lung sequelae of COVID-19 through radiological and pulmonary function assessment. DESIGN: Prospective, longitudinal, cohort study from March 2020 to March 2021. SETTING: Intensive Care Units (ICU) in a tertiary hospital in Portugal. PATIENTS: 254 patients with COVID-19 admitted to ICU due to respiratory illness. INTERVENTIONS: A chest computed tomography (CT) scan and pulmonary function tests (PFT) were performed at 3 to 6 months. MAIN VARIABLES OF INTEREST: CT-scan; PFT; decreased diffusion capacity of carbon monoxide (DLCO). RESULTS: All CT scans revealed improvement in the follow-up, with 72% of patients still showing abnormalities, 58% with ground glass opacities and 62% with evidence of fibrosis. PFT had abnormalities in 94 patients (46%): thirteen patients (7%) had an obstructive pattern, 35 (18%) had a restrictive pattern, and 58 (30%) had decreased DLCO. There was a statistically significant association between abnormalities in the follow-up CT scan and older age, more extended hospital and ICU stay, higher SAPS II and APACHE scores and invasive ventilation. Mechanical ventilation, especially with no lung protective parameters, was associated with abnormalities in PFT. Multivariate regression showed more abnormalities in lung function with more extended ICU hospitalization, chronic obstructive pulmonary disease (COPD), chronic kidney disease, invasive mechanical ventilation, and ventilation with higher plateau pressure, and more abnormalities in CT-scan with older age, more extended ICU stay, organ solid transplants and ventilation with higher positive end-expiratory pressure (PEEP). CONCLUSIONS: Most patients with severe COVID-19 still exhibit abnormalities in CT scans or lung function tests three to six months after discharge.