Chest radiograph at admission predicts early intubation among inpatient COVID-19 patients

Abstract

Objective: The 2019 Coronavirus (COVID-19) results in a wide range of clinical severity and there remains a need for prognostic tools which identify patients at risk of rapid deterioration and who require critical care. Chest radiography (CXR) is routinely obtained at admission of COVID-19 patients. However, little is known regarding correlates between CXR severity and time to intubation. We hypothesize that the degree of opacification on CXR at time of admission independently predicts need and time to intubation.

Methods: In this retrospective cohort study, we reviewed COVID-19 patients who were admitted to an urban medical center during March 2020 that had a CXR performed on the day of admission. CXRs were divided into 12 lung zones and were assessed by two blinded thoracic radiologists. A COVID-19 opacification rating score (CORS) was generated by assigning one point for each lung zone in which an opacity was observed. Underlying comorbidities were abstracted and assessed for association.

Results: One hundred forty patients were included in this study and 47 (34%) patients required intubation during the admission. Patients with CORS ≥ 6 demonstrated significantly higher rates of early intubation within 48 h of admission and during the hospital stay (ORs 24 h, 19.8, p < 0.001; 48 h, 28.1, p < 0.001; intubation during hospital stay, 6.1, p < 0.0001). There was no significant correlation between CORS ≥ 6 and age, sex, BMI, or any underlying cardiac or pulmonary comorbidities.

Conclusions: CORS ≥ 6 at the time of admission predicts need for intubation, with significant increases in intubation at 24 and 48 h, independent of comorbidities.

Key points: • Chest radiography at the time of admission independently predicts time to intubation within 48 h and during the hospital stay in COVID-19 patients. • More opacities on chest radiography are associated with several fold increases in early mechanical ventilation among COVID-19 patients. • Chest radiography is useful in identifying COVID-19 patients whom may rapidly deteriorate and help inform clinical management as well as hospital bed and ventilation allocation.

Keywords: COVID-19; Intubation; Prognosis; Radiography.

Fig. 1

Study inclusion criteria flow chart

Fig. 2

Chest radiography and opacification severity zones. a A 34-year-old man presented to the emergency department with shortness of breath was found to have COVID-19. b The lungs are divided into twelve lung zones. Lung zones were defined as apical (cranial to the azygous vein contour), mid (between azygous vein contour and superior cavoatrial junction), and basal (below superior cavoatrial junction), and were further divided into medial and lateral segments using the mid-clavicular line as landmark. Opacities were identified in the right mid medial, right basal medial, and left mid medial lung zones. A CORS of 3 was assigned. c A 48-year-old woman presented to the emergency department with cough, chest pain, and shortness of breath was diagnosed with COVID-19. Multiple opacities are identified in the bilateral lungs. This patient rapidly decompensated and was intubated within 24 h from acquisition of this radiograph. d Opacities are defined in all twelve defined lung zones; a CORS of 12 was assigned

Fig. 3

Distribution of COVID-19 opacification rating score (CORS) among 140 admitted patients. CORS for the overall cohort is presented in panel a. Lung zones were demarcated as described in Fig. 2 and a point assigned for opacity in each zone. The CORS is the summation of total opacity points on chest radiograph. The red line demarcates the cutoff of CORS ≥ 6 which was used for analysis in this study. Frequencies and distribution of lung zone opacities on the admission CXR are presented in panel b. The CORS of patients stratified by need for intubation at 7 days is presented in panel c and d

Fig. 4

a Chest radiograph severity score predicts early intubation after admission. Kaplan-Meier curves demonstrate a statistically significant difference in time to intubation after admission in patients with CORS ≥ 6 (****p < 0.0001, log-rank test). The number of patients at risk in each 24-h period is displayed below the Kaplan-Meier curves. A Kaplan-Meier curve illustrating the proportion of patients intubated in the early admission period (0–48 h) is shown in panel b