To observe the clinical characteristics and dynamic changes of laboratory results in severe and non-severe COVID-19 patients, and to analyze the related risk factors for the occurrence of severeCOVID-19.

59 patients confirmed with COVID-19 infection were included from Tongcheng People's Hospital and Xianning Central Hospital, including 12 severe patients and 47 non-severe patients. The clinical characteristics and the dynamic changes of laboratory test during hospitalization of the two groups were compared, univariate as well as multiple logistic regressions were used to analyze the risk factors of severe COVID-19.

Severe patients was older on the average age than non-severe patients, and often accompanied by a history of diabetes, hypertension, coronary heart disease and COPD. The time from symptoms onset to treatment and fever days were longer and the peak temperature were higher in severe patients (P＜0.05). Severe patients had a higher proportion of shortness of breath and bone-muscle pain, often accompanied by increased neutrophils, lymphopenia, thrombocytopenia. Elevated D-dimer, CRP, procalcitonin, AST and serum creatinine were also found in severe COVID-19 patients(P＜0.05). In the second week of hospitalization, the proportion of lymphopenia in severe and non-severe patients increased to 83.34% and 32.60%, the proportion of elevated D-dimer increased to 66.67% and 26.09%, and the proportion of elevated ALT (＞100 U/L) increased to 16.67% and 4.35%. In the third and fourth weeks, the lymphocytes of most non-severe patients returned to normal, and D-dimer, CRP and PCT decreased to normal levels. While the lymphocytes of some severe patients were still low, with high levels of ALT, D-dimer, CRP, and PCT.

In the multivariate regression analysis, it was found that elevated D-dimer was the risk factors of severe COVID-19.