2.3 | Statistical analysis
Descriptive statistics were generated to describe demographic, disease characteristics, and treatment variables to compare the distributions between patients treated at pediatric versus adult cancer centers, using chi-square tests for categorical variables and t‐tests or Kruskal-Wallis tests for continuous variables.
Kaplan-Meier survival analysis was performed to determine EFS. The log-rank test was used to compare survival between groups. Univariate and multivariable Cox proportional hazard (PH) survival analyses were performed to identify factors associated with EFS. Cox PH survival analysis results were presented as hazard ratios (HR) with 95% confidence intervals (CI). Variables that had a p-value less than 0.1 in univariate analysis were included in multivariable analysis. Prognostic factors previously reported in the literature (LOC, primary site, and sex in OGS and LOC and primary site in EWS) were included a priori in multivariable analysis.
All analyses were performed using SAS (Enterprise Guide) statistical software for Unix environment, version 9.4 (SAS Institute Inc, Cary, NC, USA). Statistical significance was defined as p-value less than 0.05. All data are reported as per the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guideline (Appendix 2 ).