Clinical characteristics of 2019-nCoV in China

Study supervision

The study was supported by the National Health Commission of China and designed by the investigators. The study was approved by the Institutional Review Board of the National Health Committee. Written informed consent was waived in light of the urgency of data collection. Data were analyzed and interpreted by the authors. All authors reviewed the manuscript and emphasized the accuracy and completeness of the data and for the study’s adherence to the protocol, available with the full text of this article at NEJM.org.

data sources

Obtained medical records and aggregate data of inpatients and outpatients with laboratory-confirmed Covid-19 virus, as reported to the National Health Commission between December 11, 2019 and January 29, 2020; The data cut-off for the study was January 31, 2020. Covid-19 was diagnosed on the basis of interim WHO guidelines.14 A confirmed case of Covid-19 was defined as a positive result on high-throughput sequencing or real-time RT-PCR testing of nasal and oropharyngeal swab samples.1 Only laboratory-confirmed cases were included in the analysis.

We obtained data on cases outside Hubei Province from the National Health Commission. Due to the high workload of doctors, three external experts from Guangzhou conducted raw data mining at Wuhan Jinyintan Hospital, where several Covid-19 patients were treated in Wuhan.

We extracted recent exposure history, clinical symptoms or signs, and laboratory findings on admission from electronic medical records. Radiological evaluations included chest radiography or computerized tomography (CT), and all laboratory examinations were performed according to the patient’s clinical care needs. We identified a radiological abnormality based on documentation or description in medical charts; If available, imaging scans were reviewed by the treating physicians in pulmonology who extracted the data. The main disagreement between two reviewers was resolved in consultation with a third reviewer. Laboratory evaluations consist of complete blood count, blood chemical analysis, coagulation test, liver and kidney function assessment, electrolyte measurements, C-reactive protein, procalcitonin, lactate dehydrogenase, and creatine kinase. We determined a Covid-19 severity score (severe versus not severe) at the time of admission using the American Thoracic Society guidelines for community-acquired pneumonia.15th

All medical records were transcribed and sent to the data processing center in Guangzhou, coordinated by the National Health Commission. A team of experienced pulmonologists reviewed and summarized the data. The data was entered into a computerized database and reviewed. If basic data was missing, requests for clarification were sent to the coordinators, who subsequently contacted the treating physicians.

Results

The primary composite endpoint was admission to the intensive care unit (ICU), use of mechanical ventilation, or death. These findings were used in a previous study to assess the severity of other serious infectious diseases, such as H7N9 infection.16 The secondary endpoints were the rate of death and the time from symptom onset to the composite endpoint to each component of the composite endpoint.

Study definitions

The incubation period was defined as the interval between the earliest possible date of contact with the source of transmission (wildlife or a person with a suspected or confirmed case) and the earliest likely date of onset of symptoms (eg cough, fever, fatigue, or muscle pain). We excluded incubation periods of less than 1 day because some patients were constantly exposed to sources of contamination; In these cases, the last date of exposure was recorded. Summary statistics of incubation periods were calculated on the basis of 291 patients with clear information regarding the exact history of exposure.

Fever was defined as an axillary temperature of 37.5°C or higher. Lymphocytopenia was defined as the number of lymphocytes less than 1,500 cells per cubic millimeter. Thrombocytopenia was defined as a platelet count of less than 150,000 per cubic millimeter. Additional definitions—including exposure to wildlife, acute respiratory distress syndrome (ARDS), pneumonia, acute renal failure, acute heart failure, and rhabdomyolysis—are available in the Supplementary Appendix, available at NEJM.org.

laboratory confirmation

Laboratory confirmation of SARS-CoV-2 was performed at the Chinese Center for Disease Prevention and Control prior to January 23, 2020, and thereafter at approved specialized care hospitals. RT-PCR assays were performed according to the protocol established by the World Health Organization.17 Details regarding laboratory confirmation processes are provided in the Supplementary Appendix.

statistical analysis

Continuous variables were expressed as means and interquartile ranges or simple ranges, as appropriate. Categorical variables were summarized as numbers and percentages. No calculation was made for missing data. Since the group of patients in our study was not derived from random selection, all statistics are descriptive only. We used ArcGIS, version 10.2.2, to plot the numbers of confirmed patients on the map. All analyzes were performed using R software, version 3.6.2 (R Foundation for Statistical Computing).

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