Background: It is unclear whether patient characteristics or features of acute COVID-19 are associated with decreased pulmonary function following a SARS-CoV-2 infection.

Aims: To describe pulmonary function 3-6 months following acute COVID-19 and to evaluate potential predictors of decreased pulmonary function.

Methods: In this prospective cohort study, 95 patients aged 40-65 years were recruited from outpatient post-COVID clinics in 5 Dutch hospitals between May 2021 and September 2022. At 3-6 months post-COVID, medical records data and biological samples were collected and questionnaires were administered. In addition, pulmonary function tests (PFTs), including spirometry and diffusion measurements, were performed. To identify factors associated with pulmonary function parameters, linear regression analyses were conducted, adjusted for covariates.

Results: In PFTs (n=89), mean±SD % of predicted was 91.2±17.2 for forced expiratory volume in 1 second(FEV1), 88.7±18.0 for forced vital capacity(FVC) and 79.8±20.1 for diffusing capacity for carbon monoxide(DLCO). DLCO was <80% of predicted in 50.6% of patients. Univariable analyses showed that age (adjusted difference[95%CI]=-1.03[-1.73,-034] per one year increase), severe acute infection (-14.56[-23.82,-5.31]), and having a pulmonary embolism during acute infection (-10.89[-22.10,0.32]) were associated with lower DLCO % predicted. Multivariable analysis showed that age and severity of acute infection were independently associated with a decreased DLCO.

Conclusion: DLCO 3-6 months following acute COVID-19 was <80% of predicted in half of the patients in the P4O2 COVID-19 cohort. Higher age and severe acute infection were independently associated with decreased DLCO.