Statistical Analyses
Descriptive statistics were used to characterize the sample at baseline and follow-up. The Behavior Assessment System for Children (BASC)42-43 Behavioral Symptoms Index and Adaptive Skills Composite and the Behavior Rating Inventory of Executive Functioning (BRIEF)44-45 Global Executive Composite, Behavioral Regulation Index, and Metacognition Index were used as primary outcome measures. One-way analysis of variance (ANOVA) was conducted to determine the differential impact of demographic, diagnostic, and treatment-related characteristics on these primary outcome measures. Pearson correlation was used to investigate the relationship between the primary outcome measures by age at baseline, SES, and the time interval between baseline and follow-up.
One-sample t-tests were used to compare mean T-scores with published normative means. Rates of impairment were calculated and defined as the frequency of scores > 1.5 S.D. above the mean of 50 (T-score > 65). Chi-square test of independence was conducted to evaluate the differences in rates of impairment by radiation field (CSI or focal). One-way ANOVA was performed to evaluate the rates of impairment by age at baseline.
Analyses were performed using SPSS version 24 (IBM 2016, Chicago, IL). Two-tailed analyses were used in all comparisons; statistical significance was defined as p < 0.05.