Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria
Christoph Schwabl
Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria
Manfred Nairz
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Philipp Grubwieser
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Katharina Kurz
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Sabine Koppelstätter
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Magdalena Aichner
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Bernhard Puchner
The Karl Landsteiner Institute, Muenster, Austria
Alexander Egger
Central Institute of Medical and Chemical Laboratory Diagnostics, University Hospital Innsbruck, Innsbruck, Austria
Gregor Hoermann
Central Institute of Medical and Chemical Laboratory Diagnostics, University Hospital Innsbruck, Innsbruck, Austria; Munich Leukemia Laboratory, Munich, Germany
Ewald Wöll
Department of Internal Medicine, St. Vinzenz Hospital, Zams, Austria
Günter Weiss
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Gerlig Widmann
Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria
Background: The optimal procedures to prevent, identify, monitor, and treat long-term pulmonary sequelae of COVID-19 are elusive. Here, we characterized the kinetics of respiratory and symptom recovery following COVID-19. Methods: We conducted a longitudinal, multicenter observational study in ambulatory and hospitalized COVID-19 patients recruited in early 2020 (n = 145). Pulmonary computed tomography (CT) and lung function (LF) readouts, symptom prevalence, and clinical and laboratory parameters were collected during acute COVID-19 and at 60, 100, and 180 days follow-up visits. Recovery kinetics and risk factors were investigated by logistic regression. Classification of clinical features and participants was accomplished by unsupervised and semi-supervised multiparameter clustering and machine learning. Results: At the 6-month follow-up, 49% of participants reported persistent symptoms. The frequency of structural lung CT abnormalities ranged from 18% in the mild outpatient cases to 76% in the intensive care unit (ICU) convalescents. Prevalence of impaired LF ranged from 14% in the mild outpatient cases to 50% in the ICU survivors. Incomplete radiological lung recovery was associated with increased anti-S1/S2 antibody titer, IL-6, and CRP levels at the early follow-up. We demonstrated that the risk of perturbed pulmonary recovery could be robustly estimated at early follow-up by clustering and machine learning classifiers employing solely non-CT and non-LF parameters. Conclusions: The severity of acute COVID-19 and protracted systemic inflammation is strongly linked to persistent structural and functional lung abnormality. Automated screening of multiparameter health record data may assist in the prediction of incomplete pulmonary recovery and optimize COVID-19 follow-up management. Funding: The State of Tyrol (GZ 71934), Boehringer Ingelheim/Investigator initiated study (IIS 1199-0424). Clinical trial number: ClinicalTrials.gov: NCT04416100
