Definitions and statistical analysis
According to our clinical practice guidelines which were drafted in
2005, failure of induction is defined as MRD>=1% at day
35-42 of remission induction. Refractory disease (RD) was defined as
leukemia persistence in patients surviving induction. Relapse was
defined as disease recurrence at any site after achieving remission.
Treatment‐related mortality (TRM) was defined as death in remission in
patients receiving treatment for ALL. Rapid early (RER) was defined as
M1 marrow (<5% blasts) on day 15, and M1 marrow with negative
MRD status (< 0.01%) at the end of Induction. Slow early
responder (SER) M2 (5-25% blasts) or M3 (>25% blasts)
marrow on Day 15 or positive MRD status (>=0.01%) at end
of induction.
Overall survival (OS) was measured from the time of entry in the
protocol to the time of death by any cause or last follow‐up. Event‐free
survival (EFS) was defined from the time of entry in the protocol to the
date of relapse or date of refractory disease post FLAG and/or
re-intensification chemotherapy, date of second cancer or death from any
cause or date of last follow up. Data analysis was performed using R
software (V4.0.4.) with calculation of Kaplan Meier estimates and
log-rank tests using “survival” package and drawing survival curves
using “survminer” package. We iterated through all possible covariates
to calculate the p-values using log-rank test. Significant covariates
were included in a multivariate Cox-regression model. Chi-square test
and Mann-Whitney test were used to evaluate categorical and numeric
variables, respectively. A p-value of =< 0.05 was considered
significant.