ABSTRACT
BACKGROUND: Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) continues to make a deadly impact on human life all over the world. Therefore, we aimed to analyze the changes in clinical characteristics of coronavirus disease 2019 (COVID-19) patients over time. METHODS: We recruited 896 patients who were admitted to the Renmin Hospital of Wuhan University between 30th January 2020 and 16st March 2020. We conducted a retrospective study collecting clinical characteristics, radiologic and laboratory findings, treatments administered, and clinical outcomes in the patients. The data collected were compared between patients with onset of illness in January 2020 and patients with onset of illness in February 2020, in Wuhan, China. Categorical data and non-normally distributed continuous data were examined by the χ2 test and the Mann-Whitney-Wilcoxon test respectively, and the Kaplan-Meier plot was used to analyze survival data. Univariate and multivariate logistic regression methods were used to explore the risk factors associated with in-hospital death. RESULTS: A total of 896 patients were enrolled; the median age was 60 (range, 47-69) years, 685 (76.5%) were categorized into group A (patients with onset of illness in January 2020), and 211 (23.5%) were categorized into group B (patients with onset of illness in February 2020). Compared with group B, group A had a higher incidence of fever (P<0.001), and a lower rate of asymptomatic individuals (P<0.001). Group A patients had a higher incidence of neutrophilia (P=0.043), an elevated D-dimer (P<0.001), and an increased lactate dehydrogenase (LDH) (P=0.002), but a lower incidence of a normal computed tomography (CT) scan (P=0.001). CD3 cell counts (P=0.015) and CD4 cell counts (P=0.04) were significantly reduced in group A patients. Critically ill patients were less frequent (P=0.005) and patients with milder disease were more common (P=0.001) in group B. The fatality rate was significantly less in group B patients (P=0.028). Multivariate regression indicated that older age (odds ratio 1.086, 95% CI: 1.061-1.111, per year increase; P<0.001) increased the risk of in-hospital death. Female sex (odds ratio 0.523, 95% CI: 0.316-0.865; P=0.012) and being in group B (odds ratio 0.423, 95% CI: 0.212-0.844; P=0.015) significantly decreased the risk of in-hospital death. CONCLUSIONS: The condition of patients with onset of illness in January was more serious than that of patients with onset of illness in February 2020. The time of onset of illness was an independent risk factor for in-hospital death comparing January and February 2020. Changing pathogenicity of SARS-CoV-2 and improved healthcare may have contributed to the results, however, more basic research is required to support this hypothesis.