Statistical analysis
Quantitative data were described by median and enumeration data was expressed as a percentage(%).We conduct Chi-square statistical significant test on categorical variables and Fisher’s exact test on observations which were less than five in number.The final follow-up was on march, 2020 and the median follow-up time was 14 months (range: 1 to 39 months). Event-free survival (EFS) was calculated from the time point of diagnosis until the following events:induction treatment failure,any relapse afterCR,second malignancy (SMN),death due to any cause. Survival rates were calculated and compared using Kaplan–Meier analysis and log-rank tests on univariable data.Cox regression analysis for multivariate data.Variables that were found statistically significant or P -value approximate to 0.1 will be included in multivariable Cox regression analysis.Statistical significance was defined as a P -value of less than 0.05.All analyses were performed using SPSS 23.0 software.