Table 4.

Linear Mixed Effects Model of IQ Change Over Time by RT Group for Focal RT Only (n = 54)^*

Parameter	Beta†	95% CI	P
Time since RT, years	−0.6	−2.0 to 0.8	.401
RT group (XRT) × time since RT, years	−1.0	−3.0 to 1.0	.342
RT group (XRT)	−3.0	−12.6 to 6.6	.541
Age at RT, years	−0.3	−1.5 to 0.9	.602
Total RT dose to tumor, Gy	−0.5	−1.6 to 0.6	.360
VP shunt	−1.5	−10.3 to 7.2	.730
Tumor location‡	3.0	−9.4 to 15.4	.640
Tumor diameter, cm‡	−3.0	−6.0 to 0.0	.051
Histology			.323
Glioma	—
Medulloblastoma/PNET	−12.0	−31.9 to 8.0	.241
Ependymoma	6.4	−10.0 to 22.8	.446
Germ cell tumor	−12.6	−31.8 to 6.6	.199
Other§	0.3	−10.6 to 11.2	.955
Performance score ≤ 80‡║	2.4	−9.5 to 14.2	.697
SES‡	−79.2	−125.7 to −32.8	.001
Race/ethnicity‡			.065
White	—
Black	−1.5	−14.4 to 11.5	.825
Hispanic/Latino	−1.6	−13.6 to 10.3	.789
Other¶	−26.5	−45.9 to −7.1	.007#
IQ test type
Leiter	—
Wechsler	−15.1	−28.9 to −1.3	.031

Abbreviations: —, reference group; IQ, intelligence quotient; PNET, primitive neuroectodermal tumor; RT, radiation therapy; SES, socioeconomic status; VP, ventriculoperitoneal; XRT, photon radiation therapy.

^*Fourteen focal patients were excluded from the model because of missing data on covariates.

^†Beta = slope.

^‡Data were missing for tumor location (n = 1), tumor diameter (n = 4), performance score (n = 8), and race/ethnicity (n = 1).

^§Other histology category includes craniopharyngioma (n = 13), choroid plexus carcinoma (n = 1), meningioma (n = 2), and neuronal glial (n = 1).

║Performance score was obtained from the Lansky/Karnofsky rating at the first clinic visit after diagnosis.

^¶Other race category includes Asian (n = 3) and American Indian (n = 1).

^#Because the overall effect for race/ethnicity was not significant, the significant result for the other versus white contrast is not interpreted as a significant effect.