Korean J Radiol.  2020 Nov;21(11):1265-1272. 10.3348/kjr.2020.0564.

Characteristics of COVID-19 Patients Who Progress to Pneumonia on Follow-Up Chest Radiograph: 236 Patients from a Single Isolated Cohort in Daegu, South Korea

• Jung HK
• Kim JY
• Lee MS
• Lee JY
• Park JS
• Hyun M
• Kim HA
• Kwon YS
• Choi SW
• Moon SM
• Suh YJ

• KMID: 2507250
• DOI: http://doi.org/10.3348/kjr.2020.0564

Abstract

Objective
We investigated the prevalence of pneumonia in novel coronavirus disease 2019 (COVID-19) patients using chest radiographs to identify the characteristics of those with initially negative chest radiographs, who were positive for pneumonia on follow-up.
Materials and Methods
Retrospective cohort data of 236 COVID-19 patients were reviewed. Chest radiography was performed on admission, with serial radiographs obtained until discharge. The ‘positive conversion group’ was defined as patients whose initial chest radiographs were negative but were positive for pneumonia during follow-up. Patients with initially positive chest radiographs were defined as the ‘initial pneumonia group.’ Patients with negative initial and follow-up chest radiographs were defined as the ‘non-pneumonia group.’ Clinical and laboratory findings were compared between groups, and predictors of positive conversion were investigated.
Results
Among 236 patients, 108 (45.8%) were in the non-pneumonia group, 69 (29.2%) were in the initial pneumonia group, and 59 (25%) were in the positive conversion group. The patients in the ‘initial pneumonia group’ and ‘positive conversion group’ were older, had higher C-reactive protein (CRP) and lactate dehydrogenase levels, and lower absolute lymphocyte counts than those in the ‘non-pneumonia group’ (all p < 0.001). Among patients with negative initial chest radiographs, age ≥ 45 years (odds ratio [OR]: 3.93, 95% confidence interval [CI]: 1.76–8.75, p = 0.001), absolute lymphocyte count < 1500 cells/µL (OR: 2.25, 95% CI: 1.03–4.89,p = 0.041), and CRP > 0.5 mg/dL (OR: 3.91, 95% CI: 1.54–9.91, p = 0.004) were independent predictors for future development of pneumonia.
Conclusion
More than a half of COVID-19 patients initially had normal chest radiographs; however, elderly patients (≥ 45 years of age) with abnormal laboratory findings (elevated CRP and low absolute lymphocyte counts) developed pneumonia on follow-up radiographs.

Keyword

Radiography; Coronavirus; COVID-19; Pneumonia; C-reactive protein; Lymphopenia; Lactate dehydrogenase