Temporal evolution of chest radiographic appearances in COVID-19 with clinicoradiological associations: a multicentre United Kingdom resident-led study

Abstract

Aim: To describe the (a) frequency of improving, static, and worsening chest radiograph (CXR) appearances; (b) differences in demographic, initial rudimentary haematological and CXR variables and these patterns; and (c) frequency of different trajectories of serial CXR evolution, in COVID-19 patients presenting consecutively.

Materials and methods: This multicentre retrospective study included all COVID-19 patients admitted from 1-30 April 2020, meeting the inclusion criteria across 24 (blinded) hospitals. Follow-up CXRs on admission, the subsequent (where available), and at 4-8 weeks were scored for the presence of parenchymal opacities across six zones. Three cohorts were defined: improved, static, and/or worsened. The chi-squared and Kruskal-Wallis tests were used to compare demographic, laboratory, and CXR variables. Trajectories of CXR evolution were assessed when all three CXRs were available (226 patients).

Results: Of 452 included patients (median age 66 years, interquartile range 54.3-79, 262 men), 211 (46.7%) improved, 140 (31%) were static, and 101 (22.3%) worsened. Improving patients were more likely younger, with a classic COVID-19 radiograph and higher initial CXR zonal severity scores (both p<0.001), while worsening patients had lower initial lymphocyte counts (p=0.008). The most frequent trajectory was worsened then improved (n=63, 27.9%) followed by static then improved (n=46, 20.4%) and static (n=42, 18.6%).

Conclusion: Most patients with COVID-19 during the first wave of the pandemic demonstrated radiographic improvement; these patients were more likely younger with classic COVID-19 appearances and initially more extensive abnormality. Conversely, radiographic deterioration was associated with lower lymphocyte counts. The three most common trajectories were worsening then improvement, static then improvement, and static throughout.