Statistical analysis
The pEFS and pOS were estimated by using the Kaplan-Meier method . Comparison between the HR-I treatment (CoALL08-09) group vs. the historical standard HR-treatment (CoALL07-03) group was performed by using the log-rank test. pEFS was defined as the time from diagnosis to first event including relapse, death by any cause in remission, second malignancy or censoring at last follow-up. pOS was defined as the time from diagnosis to death by any cause or censoring at last follow-up.
The status of patients was monitored annually on protocol-specific forms reviewed by the trial data center before data entry. A recent update of the database (September 2021) was used for this analysis.