ABSTRACT
Aim/Introduction: Many patients have reduced pulmonary diffusion capacity (DLco) after COVID-19. We assessed whether this is due to a post-COVID restrictive lung disease and/or pulmonary vascular disease. Material(s) and Method(s): In total 67 patients diagnosed with COVID-19 at our hospital in 2020 were included across three severity groups: 12 mild - not admitted to hospital, 40 moderate - admitted to hospital without intensive care unit (ICU) admission, and 15 severe - with ICU admission. At 5-months followup after SARS-CoV-2 diagnosis, lung function (spirometry, body plethysmography, DLco), high-resolution CT of the lungs (HRCT), and ventilation/perfusion (V/Q) SPECT/CT were conducted. Result(s): DLco was reduced in 42% of the patients (mild 17%, moderate 40% and severe 71%);both prevalence and degree depended on clinical severity group and was usually part of a restrictive pattern with reduced TLC. Reduced DLco was associated with ground-glass opacification and pulmonary fibrosis found on HRCT and matched V/Q SPECT defects, but not with mismatched perfusion defects on V/Q SPECT/CT. Conclusion(s): The severity-dependent decline in DLco observed 5 months after COVID-19 is related to restrictive lung disease but not to pulmonary vascular disease.