Study design and COVID-19 patients
We performed a retrospective study on patients with COVID-19 at Jeju National University Hospital in Jeju Island, South Korea. This hospital was designated the national negative pressure isolation ward responsible for treating patients with high-risk COVID-19 in South Korea. The study was approved by the Institutional Review Board (IRB) at the Jeju National University Hospital (IRB file no. 2020-10-019).
Patients admitted from August 2020 to July 2021 and who had confirmed SARS-CoV-2 infection, were eligible to participate in the study. During the study period, 430 cases were confirmed to be positive for SARS-CoV-2 using real-time reverse transcriptase polymerase chain reaction (RT-PCR) on Jeju Island. Of these confirmed patients, 188 patients were admitted to our hospital, and 109 were analysed in the present study (Table 1).
Demographic and clinical characteristic data included the patients’ demographics (age, sex, and body mass index), past medical history and comorbidity index score (CCI), source of exposure risk to SARS-CoV-2, symptom presentation, type of oxygen therapy, hospital treatment (inotropes, extracorporeal membrane oxygenation), duration of hospitalization, and mortality. Laboratory variables confirmed in the Laboratory Department of Jeju National University Hospital were retrospectively obtained from the registry database.
The severity of illness was classified into the following five groups according to the National Institute of Health’s criteria based on the patient’s worst condition during hospitalization: asymptomatic, mild, moderate, severe, and critical [Reference: National Institutes of Health (NIH). Clinical spectrum of SARS-CoV-2 infection. Available at: https://www.covid19treatmentguidelines.nih.gov/overview/clinical-spectrum/. Accessed 25 June, 2022].