Chest CT Lung Abnormalities 1 Year after COVID-19: A Systematic Review and Meta-Analysis.

Background Radiological lung sequelae may explain the persistence of respiratory complaints in post-COVID-19 condition (long-COVID). Purpose To perform a systematic review and meta-analysis of the prevalence and type of COVID-19 residual lung abnormalities at 1-year chest CT. Materials and Methods A literature search of PubMed, Web of Science, Embase, and Medline databases was performed from January 2020 to January 2023. Full-text reports of CT lung sequelae in adults (≥18 years) with confirmed COVID-19 at 1-year follow-up were included. The prevalence of any residual lung abnormality and type (fibrotic or not) was analyzed according to the Fleischner Glossary. The meta-analysis included studies with chest CT data assessable in no less than 80% of individuals. A random-effects model was used to estimate pooled prevalence. Multiple sub-group (country, journal category, methodological quality, study setting, outcomes) and meta-regression analyses were performed to identify potential sources of heterogeneity. I 2 statistics estimated low (25%), moderate (26-50%) and high (>50%) heterogeneity. 95% Prediction Intervals (95% PIs) were computed to describe the expected estimates range. Results Of 22 709 records, 21 studies were reviewed (20 prospective, 9 from China, and 7 in radiology journals). The meta-analysis included 14 studies with chest CT data in 1854 of 2043 individuals (M/F: 1109/934). Estimates of lung sequelae were highly heterogeneous (7.1-96.7%), with a pooled frequency of 43.5% (I 2 =94%; 95% PI: 5.9%, 90.4%). This also applied to single non-fibrotic changes, including ground glass opacity, consolidations, nodules/masses, parenchymal bands, and reticulations. The prevalence range of fibrotic traction bronchiectasis/bronchiolectasis was 1.6-25.7% (I 2 =93%; 95% PI: 0.0%, 98.6%;); honeycombing was unremarkable (0-1.1%; I 2 =58%; 95% PI: 0%, 60%). Lung sequelae were unrelated to any characteristics of interest. Conclusion The prevalence of COVID-19 lung sequelae at 1-year chest CT is highly heterogeneous among studies. Heterogeneity determinants remain unknown suggesting caution in data interpretation with no convincing evidence. PROSPERO (CRD42022341258) Keywords: COVID-19 pneumonia, pulmonary fibrosis, chest CT, long-COVID, systematic review, metaanalysis See also the editorial by Parraga and Svenningsen in this issue.