Study Design and Participants
One hundred eighty discharged patients were registered at WRCH. WRCH, one mile away from Huanan Seafood Wholesale Market to which SARS-CoV-2 was tracked back, is a trusteeship hospital of Union Hospital and one of the first hospitals admitting COVID-19 patients only. All patients were diagnosed with COVID-19 according to the guideline of SARS-CoV-2 (Trial Version 5 to 7 of the Chinese Government). The data of included cases have been submitted to the Chinese Center for Disease Control and Prevention. We analyzed epidemiological, demographic, clinical and radiological features, and laboratory data. Outcomes including length of stay, discharges and fatality were followed up and recorded until March 6th, 2020. The study was approved by WRCH Ethics Committee and written informed consent obtained from each subject before enrolment, followed by retrospective data collection.
Data and Specimen Collection
Individuals confirmed to have COVID-19 by SARS-CoV-2 real-time reverse transcriptase–polymerase chain reaction (RT-PCR) were eligible for inclusion in this study. Data were collected at Wuhan Red Cross Hospital that provided care for these patients. Data from electronic health records were summarized using a standardized data collection form. Two researchers independently reviewed the data collection forms for accuracy.
Specimens (nasopharyngeal swabs) were collected at multiple time points in the first 2 weeks following study enrollment and tested by RT-PCR for the presence of SARS-CoV-2. After collection, the throat swabs were placed into a collection tube with 200 μL of virus preservation solution, and total RNA was extracted within 2 hours using the respiratory sample RNA isolation kit ( Union hospital, Tongji Medical University, Huazhong university of Science and Technology and ADICON clinical laboratory). After standing at room temperature for 30 minutes, the collection tube was centrifugated at 8000 rpm/min for a few seconds. The suspension was used for RT-PCR assay of SARS-CoV-2. RT-PCR assay was performed under the following conditions: incubation at 50 °C for 15 minutes and 95 °C for 15 minutes, 45 cycles of denaturation at 94 °C for 15 seconds, and extending and collecting fluorescence signal at 55 °C for 45 seconds. RT-PCR cycle threshold values were collected. A cycle threshold value (Ct-value) less than 40 was defined as a positive test result. The cycle threshold value correlates with the number of copies of the virus in a biological sample, in an inversely proportional and exponential manner. Sequencing of PCR products of the RNA-dependent RNA polymerase (RdRp) gene were used to construct phylogenetic trees. (CoV-N-P: 5' FAM-TTGCCCCCAGCGCTTCA-BHQ1 3'; CoV-N-F: 5' TTGGGGACCAGGAACTAAT 3'; CoV-N-R: 5' GAAGGTGTGACTTCCATGC 3'; ORF1ab-P: 5' HEX-TCCCACCCAAGAATAGCATAGATGC-BHQ1 3'; ORF1ab-F1: 5' TTTAGATATATGAATTCACAGGGA 3'; ORF1a-R1: 5' ACCAACACCCAACAATTTAAT 3'; RNP-F: AGATTTGGACCTGCGAG ; RNP-R: ACTGAATAGCCAAGGTGAG ; RNP-P: 5’ Cy5-TCCACAAGTCCGCGCAGAG-BHQ2 3’)
Clinical Management
Epidemiological information, clinical manifestations, laboratory results, radiological characteristics, treatments and outcomes were recorded during the hospital stays and then collected from the medical records. All data were checked by two trained physicians (J.L. and N.X.). Patients were asked about basic information, medical history, exposure history, symptoms and comorbidities. Acute respiratory distress syndrome (ARDS) was defined according to the Berlin definition [6]. As part of standard of care, complete blood cell count, tests of kidney and liver function, and measurement of C-reactive protein and lactate dehydrogenase levels were performed. Respiratory samples were tested for influenza and other respiratory viruses with a multiplex PCR assay. Treatment measures included symptomatic therapy, antiviral therapy, corticosteroid therapy and respiratory support. All patients received supportive therapy, including supplemental oxygen when saturations as measured by pulse oximeter dropped below 92%. Patients clinically suspected of having community-acquired pneumonia were administered empirically.
Informed consent for collection of clinical data from infected individuals was granted by the Wuhan Red Cross Hospital Committee. Written informed consent was obtained from study participants for collection of biological samples after review and approval of the study protocol by the institutional ethics committee.
Imaging analysis
All COVID-19 patients were from WRCH and were imaged with1-mmslice thickness CT on a Siemens SOMATOM go.Top 64 scanner (Siemens Healthineers, Suzhou, China). Scanning field of view (FOV) 413×413mm, tube voltage 130kV, tube current 138mA, pitch 0.6, reconstruction layer thickness 1.5mm. Lung window reconstruction was performed using high-resolution algorithm. After inhaling, the patient held his breath to acquire images, and the scanning range was from the lung tip to the lung bottom. All CT images were reviewed by two fellowship-trained cardiothoracic radiologists with approximately five years of experience each (X.L, F.F, XF.L, D.Z, Y.S, S.H) using a viewing console. Imaging was reviewed independently and final decisions reached by consensus are reported. No negative control cases were examined. For each patient, the chest CT scan was evaluated for the following characteristics: (1) presence of ground-glass opacities, (2) presence of consolidation, (3) laterality of ground-glass opacities and consolidation, (4) number of lobes affected where either ground-glass or consolidative opacities were present, (5) degree of involvement of each lung lobe in addition to overall extent of lung involvement measured by means of a “total severity score” as detailed below, (6) presence of nodules, (7) presence of a pleural effusion, (8) presence of thoracic lymphadenopathy (defined as lymph node size of ≥10 mm in short-axis dimension), (9) airways abnormalities (including airway wall thickening, bronchiectasis, and endoluminal secretions), (10) axial distribution of disease (categorized as no axial distribution of disease, central “peribronchovascular” predominant disease, or peripheral predominant disease), and (11) presence of underlying lung disease such as emphysema or fibrosis. Other abnormalities, including linear opacities, opacities with a rounded morphology, opacities with a “reverse halo” sign, opacities with a “crazy-paving” pattern, and opacities with intralesional cavitation, were noted. Ground-glass opacification was defined as hazy increased lung attenuation with preservation of bronchial and vascular margins, whereas consolidation was defined as opacification with obscuration of margins of vessels and airway walls. Each of the five lung lobes was assessed for degree of involvement and classified as none (0%), minimal (1 - 25%), mild (26 - 50%), moderate (51 - 75%), or severe (76 - 100%). No involvement corresponded to a lobe score of 0, minimal to a lobe score of 1, mild to a lobe score of 2, moderate to a lobe score of 3, and severe to a lobe score of 4. An overall lung “total severity score” was reached by summing the five lobe scores (range of possible scores, 0 - 20) [7]. The amount of time between the initial appearance of patient symptoms and the date of admission as well as the date of the initial chest CT examination was noted for each patient.
Statistical Analysis
Categorical variables were described as frequency rates and percentages, and continuous variables were described using median, minimum and maximum grades. SPSS (Statistical Package for the Social Sciences, version 25) was used for all analyses. P < 0.05 was considered as statistically significant. Continuous variables were expressed as median (range) and compared between independent groups by Student’s t tests; categorical variables were expressed as number (%) and compared by χ² tests or Fisher’s exact tests.