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

Abstract

Background The coronavirus infectious disease (COVID-19) pandemic is an ongoing global health care challenge. Up to one third of hospitalised patients develop severe pulmonary complications and ARDS. Pulmonary outcomes following COVID-19 are unknown. Methods The Swiss COVID-19 lung study is a multicentre prospective cohort investigating pulmonary sequela of COVID-19. We report on initial follow-up 4 months after mild/moderate or severe/critical COVID-19 according to the WHO severity classification. Results 113 COVID-19 survivors were included (mild/moderate 47, severe/critical 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 (DLCO) %-predicted, reduced 6-MWD, and exercise-induced oxygen desaturation. After adjustment for potential confounding by age, sex, and BMI, patients after severe/critical COVID-19 had a 20.9 (95% CI 12.4–29.4, p=0.01) lower DLCO %-predicted at follow up. DLCO %-predicted was the strongest independent factor associated with previous severe/critical disease when age, sex, BMI, 6MWD, and minimal SpO₂ at exercise, were included in the multivariable model (adjusted odds ratio [OR] 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 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. A systematic follow-up for survivors needs to be evaluated to optimise care for patients recovering from COVID-19.