Longitudinal Chest X-ray Scores and their Relations with Clinical Variables and Outcomes in COVID-19 Patients

Coronavirus disease 2019 (COVID-19) [ 1, 2, 3] has already infected 676 million people and killed more than 6.88 million worldwide (14 March 2023). The widespread outbreaks and recent spikes around the world, and the likelihood of recurrences have strained and will continue to strain healthcare resources. Radiological imaging of the lung is an essential tool in evaluating COVID-19 lung infection.

Evaluating Imaging Modalities

In the early days of the pandemic, computed tomography (CT) [ 4] was used in China when reverse transcription polymerase chain reaction (RT-PCR) was less reliable and had a long turnaround time [ 5, 6]. CT is, however, prone to cross-contamination and, thus, it is not widely used in the context of COVID-19 in the United States and elsewhere in the world, especially in the intensive care setting, due to the risk of cross-infection. By contrast, a portable chest X-ray (CXR) is convenient, readily available, can be brought to the patient’s bedside, and can be readily disinfected between uses [ 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]. Although a CXR has inferior diagnostic quality to CT, CXRs can be used to visualize characteristic ground-glass opacities and consolidation in the lungs associated with COVID-19 infection, helping with clinical diagnosis [ 17].

Study Methodology and Patient Groups

This study evaluated the temporal characteristics of lung chest X-ray (CXR) scores in COVID-19 patients during hospitalization and how they relate to other clinical variables and outcomes (alive or dead). This is a retrospective study of COVID-19 patients. CXR scores of disease severity were analyzed for the following populations:

• General floor group: survivors ( N = 224) versus non-survivors ( N = 28).
• Invasive mechanical ventilation (IMV) group: survivors ( N = 92) versus non-survivors ( N = 56).

Unpaired t-tests were used to compare survivors and non-survivors and between time points. Comparison across multiple time points used repeated measures ANOVA and corrected for multiple comparisons.

Key Results and Clinical Findings

For general-floor patients, non-survivor CXR scores were significantly worse at admission compared to those of survivors ( p 0.05). For IMV patients, survivor and non-survivor CXR scores were similar at intubation ( p > 0.05), and both improved at outcome ( p 0.05).

Clinical Correlations:

CXR scores were significantly correlated with the following laboratory findings and clinical parameters:

• lactate dehydrogenase
• respiratory rate
• D-dimer
• C-reactive protein
• procalcitonin
• ferritin
• SpO2
• lymphocyte count ( p < 0.05)

Diagnostic Significance

Longitudinal CXR scores have the potential to provide prognosis, guide treatment, and monitor disease progression. CXRs have become increasingly relevant as they help clinical diagnosis through the visualization of ground glass opacity, consolidation, and infiltrates.