Number of deaths
None showed a significant difference (P > 0.05) and both with low heterogeneity (I2=0%). The time operate surgery <3 month vs. >=3 month (OR, 1.91; 95% Cl, 0.26 to 14.26);The time operate surgery <6 month vs. >=6 month (OR, 0.73; 95% Cl, 0.10 to 5.35).