Methods
This is a retrospective cohort study of 59 patients with confirmed COVID-19 pneumonia hospitalized at Infection Division of Union Hospital, Huazhong University of Science and Technology in Wuhan, China from January 25 to February 15, 2020. All patients were diagnosed with COVID-19 pneumonia according to World Health Organization interim guidance7. A retrospective review of the characteristics of these patients during the whole hospital period was performed through the electronic medical record system of our hospital, the last was monitored up to March 15, 2020. The ethics committee of Union Hospital (Wuhan, China) approved this study.
The clinical classification of COVID-19 reference the Diagnosis and Treatment Plan of COVID-19 suggested by National Health Commission of China8 (the seventh edition). The ordinary COVID-19 was defined to with fever, respiratory or other symptoms, but pneumonia asterisk in imaging procedure. The severe COVID-19 was defined as meeting any one of following items: Respiratory rate≥30 breaths /min; Arterial oxygen saturation≤93% at rest; PaO2/FiO2≤300 mmHg. All patients were treated with supportive care whatever they may needed respectively, including administration of oxygen (nasal cannula, noninvasive mechanical ventilation, invasive mechanical ventilation (IMV), or IMV with extra corporeal membrane oxygenation), antibiotic, antiviral and anticoagulant therapy, immunomodulator or methylprednisolone and so on. All of patients who were treated anticoagulant therapy in this study were precautionary, Low Molecular Weight Heparin (LMWH) (40-60mg enoxaparin/day) for 6 days at least or longer. Patients underwent blood routine blood test, coagulation, and biochemical tests and chest x-rays or computed tomography many times. For example, D-Dimer monitoring per 2-4d until it became stable and normal. It should be noted that all the clinical data used in this study were collected from the first day of hospital admission except D-Dimer that from the diverse stages of the diseases many times.
The evaluation of outcomes consisted of the time of CT imaging improvement was observed first time, hospital-stay time and the clinical improvement during 7 days and 14 days, defined as the change in oxygen support reference the seven-category ordinal scale9. The seven-category ordinal scale consisted of the following categories: 1, not hospitalized with resumption of normal activities; 2, not hospitalized, but unable to resume normal activities; 3, hospitalized, not requiring supplemental oxygen; 4, hospitalized, requiring supplemental oxygen; 5, hospitalized, requiring nasal high flow oxygen therapy, noninvasive mechanical ventilation, or both; 6, hospitalized, requiring ECMO, invasive mechanical ventilation, or both; and 7, death.
Normally and abnormally distributed quantitative variables were compared using the Student’s t-test and the Mann–Whitney U test, respectively. Categorical variables were compared using the chi-squared test. The results were given as the mean± standard deviation, median (interquartile range), or number (percentage), wherever appropriate. The level of the D-Dimer was reviewed by bivariate logistic regression analysis for their ability to predict states of illness. Survival curves were developed using the Kaplan-Meier method with log-rank test. A P value<0.05 was considered statistically significant. All analyses were performed with SPSS 25.0 for windows.