COVID-19: could CT provide the best population level biomarker? Incidental COVID-19 in major trauma patients suggests higher than predicted rates of infection in London

Abstract

Aim: To evaluate incidental findings in major trauma patients, and to explore whether computed tomography (CT) could be used to assess prevalence and estimate disease spread in the general population.

Materials and methods: The study population included all patients admitted following major trauma between 1 January 2020 and 30 April 2020 with CT including the lungs (n=523). Major trauma patients admitted pre-COVID-19 from 1-31 January and 1-31 March 2019 comprised a control group (n=252). The assessing radiologists, blinded to the time period, used double reading with consensus to determine if the patient had CT signs of COVID-19. Lung appearances were classified as no evidence of COVID-19; minor signs; or major signs. The proportion of patients with incidental COVID-19 changes was recorded over the study period, and the percentage of the population who had been affected by COVID-19 by the end of April 2020 estimated.

Results: CT appearances consistent with COVID-19 began to exceed a background pre-COVID rate in the second week of February and did not decline until 2 weeks after lockdown. By the end of April 2020, approximately 45% of the population had been infected.

Conclusions: CT of major trauma patients can be used to monitor the spread of COVID-19. This novel technique could be used retrospectively or prospectively anywhere where trauma scans are available, to monitor the disease in the local population.

Figure 1

Methodology for identification of study and control groups.

Figure 2

Histogram of ages of patients in study and control groups. Study: n=523, mean 54.9 (SD 23.9), median 56, range 1–100; control: n=252, mean 49.9 (SD 23.2) median 47, range 16–99.

Figure 3

Increase in COVID-19 signs (with background prevalence of signs as line at 2.4% and 3-week moving average as the green line). Start of impact estimated as the second week in February and lockdown was on 23 March.

Figure 4

Select cases from the study cohort. (a,b) Images of an 84-year-old man demonstrating bilateral multifocal ground-glass changes distributed mainly peripherally with perilobular features in the lower lobes and regarded as major findings. (c) Image of an 86-year-old woman showing peripheral ground glass change, but confined to one lung and regarded as minor change. (d) Image of a 19-year-old man showing peripheral rounded ground-glass changes confined to one lung regarded as minor change.

Figure 5

Select images from a scan performed in March 2019 (control group) in a 52-year-old man showing multifocal ground-glass opacities both rounded and peripheral in a pattern closely resembling those of COVID-19.