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Observational Study
. 2021 Apr 29;57(4):2003690.
doi: 10.1183/13993003.03690-2020. Print 2021 Apr.

Pulmonary function and radiological features 4 months after COVID-19: first results from the national prospective observational Swiss COVID-19 lung study

Sabina A Guler  1 , Lukas Ebner  2 , Catherine Aubry-Beigelman  3 , Pierre-Olivier Bridevaux  4 , Martin Brutsche  5 , Christian Clarenbach  6 , Christian Garzoni  7   8 , Thomas K Geiser  1   9 , Alexandra Lenoir  10 , Marco Mancinetti  11 , Bruno Naccini  12 , Sebastian R Ott  13 , Lise Piquilloud  14 , Maura Prella  10 , Yok-Ai Que  15 , Paula M Soccal  16 , Christophe von Garnier  10 , Manuela Funke-Chambour  1   9
Affiliations
Observational Study

Pulmonary function and radiological features 4 months after COVID-19: first results from the national prospective observational Swiss COVID-19 lung study

Sabina A Guler et al. Eur Respir J. .

Abstract

Background: The infectious coronavirus disease 2019 (COVID-19) pandemic is an ongoing global healthcare challenge. Up to one-third of hospitalised patients develop severe pulmonary complications and acute respiratory distress syndrome. Pulmonary outcomes following COVID-19 are unknown.

Methods: The Swiss COVID-19 lung study is a multicentre prospective cohort investigating pulmonary sequelae of COVID-19. We report on initial follow-up 4 months after mild/moderate or severe/critical COVID-19 according to the World Health Organization severity classification.

Results: 113 COVID-19 survivors were included (mild/moderate n=47, severe/critical n=66). We confirmed several comorbidities as risk factors for severe/critical disease. Severe/critical disease was associated with impaired pulmonary function, i.e. diffusing capacity of the lung for carbon monoxide (D LCO) % predicted, reduced 6-min walk distance (6MWD) and exercise-induced oxygen desaturation. After adjustment for potential confounding by age, sex and body mass index (BMI), patients after severe/critical COVID-19 had a D LCO 20.9% pred (95% CI 12.4-29.4% pred, p=0.01) lower at follow-up. D LCO % pred was the strongest independent factor associated with previous severe/critical disease when age, sex, BMI, 6MWD and minimal peripheral oxygen saturation at exercise were included in the multivariable model (adjusted odds ratio per 10% predicted 0.59, 95% CI 0. 37-0.87; p=0.01). Mosaic hypoattenuation on chest computed tomography at follow-up was significantly associated with previous severe/critical COVID-19 including adjustment for age and sex (adjusted OR 11.7, 95% CI 1.7-239; p=0.03).

Conclusions: 4 months after severe acute respiratory syndrome coronavirus 2 infection, severe/critical COVID-19 was associated with significant functional and radiological abnormalities, potentially due to small-airway and lung parenchymal disease. A systematic follow-up for survivors needs to be evaluated to optimise care for patients recovering from COVID-19.

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Conflict of interest statement

Conflict of interest: S.A. Guler has nothing to disclose. Conflict of interest: L. Ebner has nothing to disclose. Conflict of interest: C. Beigelman reports personal fees for lectures from AstraZeneca and Boehringer, outside the submitted work. Conflict of interest: P-O. Bridevaux has nothing to disclose. Conflict of interest: M. Brutsche has nothing to disclose. Conflict of interest: C. Clarenbach reports personal fees from Roche, Novartis, Boehringer, GSK, AstraZeneca, Sanofi, Vifor and Mundipharma, outside the submitted work. Conflict of interest: C. Garzoni has nothing to disclose. Conflict of interest: T.K. Geiser has nothing to disclose. Conflict of interest: A. Lenoir has nothing to disclose. Conflict of interest: M. Mancinetti has nothing to disclose. Conflict of interest: B. Naccini has nothing to disclose. Conflict of interest: S.R. Ott has nothing to disclose. Conflict of interest: L. Piquilloud has nothing to disclose. Conflict of interest: M. Prella has nothing to disclose. Conflict of interest: Y-A. Que has nothing to disclose. Conflict of interest: P.M. Soccal has nothing to disclose. Conflict of interest: C. von Garnier has nothing to disclose. Conflict of interest: M. Funke-Chambour has nothing to disclose.

Figures

FIGURE 1
FIGURE 1
Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram of the study. SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; BMI: body mass index; DLCO: diffusing capacity of the lung for carbon monoxide; 6MWT: 6-min walk test; CT: computed tomography.
FIGURE 2
FIGURE 2
Variables associated with past coronavirus disease 2019 (COVID-19) severity. Association of demographic and functional parameters with mild/moderate and severe/critical COVID-19. Odds ratios and corresponding 95% confidence intervals from unadjusted analysis and individual multivariable models for each parameter adjusting for confounding by age and sex. BMI: body mass index; TLC: total lung capacity; FVC: forced vital capacity; DLCO: diffusing capacity of the lung for carbon monoxide; FEV1: forced expiratory volume in 1 s; PaO2: arterial oxygen tension; 6MWD: 6-min walk distance; SpO2: peripheral oxygen saturation.
FIGURE 3
FIGURE 3
Characteristic radiological changes of a patient with severe sequelae 3 months after coronavirus disease 2019 (COVID-19) pneumonia. Extensive involvement of both lungs is present in a patient 3 months after severe COVID-19 pneumonia. Diffuse mosaic attenuation pattern in all lung lobes seen on a) axial 1-mm-thick computed tomography (CT) scan and b) 10-mm-thick minimum intensity projection (mIP) slices, c) 1-mm-thick CT and d) 10-mm-thick mIP sagittal reformats in lung windowing. This combines classical features of lung fibrosis with architectural distortion, reticulations, honeycombing (arrowhead in a) and traction bronchiectasis (straight arrows in a−d), as well as sharply demarcated areas of low attenuation in both lungs (circles in a−d). Clusters of contiguous hypoattenuating lobules and traction bronchiectasis are better visualised on mIP images with narrow window settings (b and d). Note the bulging of the interlobular septae (b and d, curved arrows) as well as the subpleural pneumatocele in c and d.
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