2.1 Study Design and Participants
This single-center retrospective study included consecutive patients diagnosed with COVID-19 at Wuhan Huoshenshan Hospital in China, between February 4 and April 10, 2020. The Wuhan Huoshenshan Hospital was built in ten days due to the extent of the pandemic, which exceeded the existing health system capacity. Most of the patients admitted to the Huoshenshan Hospital were transferred from other hospitals. The study design was approved by the institutional ethics board. Written informed consent was waived due to the urgency of the COVID-19 pandemic.
A total of 3,046 adult patients with COVID-19 were initially screened for the study. Individuals without information regarding disease severity, survival status, and patients with suspected CAD but not diagnosed were excluded. In the remaining cohort of 2,954 patients, 1,439 patients were mild/moderate cases and 1,515 were severe/critical cases. The disease severity was determined according to the clinical classification criterion in the Diagnosis and Treatment Protocol for Novel Coronavirus Pneumonia released by the National Health Commission of China (7th edition) (Pan et al., 2020). Patients who met any of the following criteria were diagnosed as a severe case: (1) shortness of breath defined by respiration rate ≥30 breaths/min, (2) oxygen saturation ≤ 93 at rest, and (3) alveolar oxygen partial pressure/fraction of inspiration O2(PaO2/FiO2) ≤ 300 mmHg (1 mmHg=0.133 kPa). Patients whose pulmonary imaging showed significant progression of lesions > 50% within 24-48 hours were also treated as severe cases. Patients who met any of the following conditions were diagnosed as critically severe: (1) respiratory failure requiring mechanical ventilation, (2) shock, and (3) organ failure needing intensive care unit (ICU) monitoring and treatment. In addition, the severe/critical cohort was categorized into two groups based on the presence or absence of pre-existing CAD (165/1,515 [10.9%] and 1350/1,515 [89.1%], respectively), according to clinical diagnosis and/or medical history on admission.