Statistical analysis
Demographic and clinical characteristics of patients with COVID-19 were analyzed using descriptive statistics. The Mann-Whitney U test and Student t-test were used to determine significant differences between continuous variables, as appropriate. The adjusted Chi-square test was used to determine significant differences between categorical variables. Statistical significance was set at two-sided P-values ≤ 0.05. All analyses were performed with Statistical Product and Service Solutions (SPSS) version 21 (IBM Corp, Armonk, NY).