After a follow-up period of 4 months, severe/critical coronavirus disease 2019 (COVID-19) was associated with significant lung function changes and radiologic abnormalities in patients, according to study results published in The European Respiratory Journal.

In the multicenter Swiss COVID-19 study, researchers examined patients’ lung function and radiologic images 4 months after recovery from either mild/moderate or severe/critical COVID-19. Carbon monoxide diffusing capacity (DLCO), and 6-minute walk distance tests were also performed.

Of the 113 COVID-19 survivors, 47 were classified as mild/moderate and 66 were classified as severe/critical according to the World Health Organization (WHO) severity classification. Comorbidities associated with impaired pulmonary function were more likely to lead to severe/critical disease. While smoking history was not significantly different between patients with mild/moderate and severe/critical COVID-19, BMI was significantly higher in patients with severe/critical vs mild/moderate disease. Common comorbidities included arterial hypertension, diabetes, chronic obstructive pulmonary disease (COPD), and chronic renal failure.

After adjustment for potential confounding factors such as age, sex, and BMI, patients with severe/critical COVID-19 had a 20.9 lower DLCO percent predicted (P =.01) at follow-up. When age, sex, BMI, 6-minute walk distance, and minimal SpO2 (oxygen saturation) at exercise were included in the multivariable model, DLCO percent predicted was the strongest independent factor associated with previous severe/critical disease. Furthermore, mosaic hypoattenuation on chest computed tomography was significantly associated with previous severe/critical COVID-19 during the follow-up period (adjusted odds ratio, 11.7; P =.03).

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“Four months after SARS CoV-2 infection, severe/critical COVID-19 was associated with significant functional and radiological abnormalities, potentially due to small airway and lung parenchymal disease,” the study authors wrote. “A systematic follow-up for survivors needs to be evaluated to optimize care for patients recovering from COVID-19.”


Guler SA, Ebner L, Beigelman C, et al. Pulmonary function and radiological features four months after COVID-19: first results from the national prospective observational Swiss COVID-19 lung study. Eur Respir J. Published online January 8, 2021. doi:10.1183/13993003.03690-2020