1. Case source and inclusion criteria
This study was approved by the Medical Ethics Review Board of Wuhan University of Science and Technology (No. 202009).
1) All cases came from Tianyou Hospital and Puren Hospital, affiliated Hospital of Wuhan University of Science and Technology from January 18, 2020 to February 26, 2020, tested for SARS-CoV-2 pathogenic nucleic acid Positive hospitalized cases;
2) Completed the laboratory data collection and clinical condition assessment at the three time points required by this study;
3) Study composite endpoint cures discharged patients and deaths before February 26, 2020; cases being treated in hospital on February 26, 2020.
2. Exclusion criteria
Those who failed to collect laboratory data in three times.
3. Criteria for evaluation of clinical conditions
1) Case classification
According to the COVID-19 diagnosis and treatment plan issued by the National Health Commission of China, it is divided into 4 types: mild, moderate, severe and critical. In the analysis of this study, the patients of mild type were merged into moderate type.
Mild type: mild clinical symptoms, no pneumonia on imaging
Moderate type: Symptoms such as fever, respiratory tract, pneumonia can be seen on imaging.
Severe type: According with any of the following.
(1) Shortness of breath, RR > 30 Times / minute.
(2) At rest, Oxygen saturation ≤ 93%.
(3) PaO2 /FiO2 ≤ 30mmHg(1mmHg = 0.133kPa), Pulmonary imaging showed significant progression of > 50% within 24 to 48 hours.
Critical type: One of the following conditions:
(1) Have respiratory failure and require mechanical ventilation;
(3) Combining other organ failure requires ICU monitoring treatment.
This study mainly studied the demographic characteristics, disease severity and outcome of COVID-19 patients. To optimize the research program, we mixed light and common types into light and common types according to the research purpose and clinical practice.
2) Clinical outcome
According to the clinical characteristics, the patients were divided into four types: discharge, improvement, aggravation and death.
4. Treatment method
According to the COVID-19 diagnosis and treatment plan issued by the National Health Commission of China, patients generally receive effective oxygen therapy, lopinavir / ritonavir and other drug antiviral treatments, and provide respiratory and circulatory support treatment for patients with severe and critical illness.
5. Composite endpoints of the study
By February 26, 2020, the number of discharge and death cases before February 26, 2020 should be counted, and the length of stay in the hospital should be more than 7 days. The changes of their conditions should be evaluated, and the outcome indicators should be improved, aggravated and stable.
6. Experimental data collection
The experimental data were collected at three time points: admission, 3–5 days of hospitalization, and the composite end point. At the same time, clinical typing, disease severity and outcome were determined, and the corresponding length of hospitalization was collected.
The specific methods of blood routine test and CRP test were as follows:
1) The venous blood of the subjects was extracted in the fasting state of the patients in the morning, and the venous blood was placed in a 2 ml EDTA-K2 anticoagulant tube and a 5 mL procoagulant tube respectively, mixed upside-down, and sent for timely examination.
2)2 ml EDTA-K2 anticoagulant whole blood samples were put into automatic hemocyte analyzer for routine blood test.
3)The 5 ml procoagulant tube was put into an ordinary low-speed centrifuge and centrifuge at 3000 rpm/min for 10 min. After the serum was separated, the sample was put into a biochemical analyzer and the CRP level in the blood samples was detected by immunoturbidimetry.
4) The normal reference range of CRP is < 3 mg/L; The normal reference range of lymphocytes is 1.1 × 109/ L-3.2 × 109/ L.
7. Analytical methods
SPSS25.0 software was used for statistical analysis. Non-parametric test (Mann-Whitney test) was used for quantitative data with skewed distribution and uneven variance to analyze differences between groups, and chi-square test was used for qualitative data to analyze differences between groups, if the theoretical frequency is less than 1, the Fisher exact probability test method is adopted. Survival analysis was used to determine the difference in survival time distribution of patients under different conditions during clinical observation. The risk degree of admission type and death outcome of each factor was analyzed by binary regression model and multiple regression model. The diagnostic value of CRP, L and other indicators on the death outcome was analyzed by the receiver operating characteristic curve (ROC), and the area under the curve (AUC) and its 95% CI were calculated. The optimal threshold value is determined by the maximum approximate index, providing both sensitivity and specificity. The test level selected for this statistical analysis was α = 0.05, and P < 0.05 indicated that the difference was statistically significant.