Patients in the death group exhibited significantly lower lymphocyte count (0.63 [0.40, 0.79] × 10/L vs. 1.00 [0.72, 1.27] × 10/L, Z = 8.037, P < 0.001) and lymphocyte/WBC ratio (7.10 [4.45, 12.73]% vs. 23.5 [15.27, 31.25]%, Z = 10.315, P < 0.001) on admission, and the lymphocyte/WBC ratio continue to decrease during hospitalization (7.10 [4.45, 12.73]% vs. 2.91 [1.79, 6.13]%, Z = 5.242, P < 0.001).