Table 3.

Linear Mixed Effects Model of IQ Change Over Time by RT Group for CSI Only (n = 69)^*

Parameter	Beta†	95% CI	P
Time since RT, years	−0.8	−1.9 to 0.4	.203
RT group (XRT) × time since RT, years	−0.1	−1.6 to 1.4	.890
RT group (XRT)	−12.5	−21.1 to −3.9	.004
Age at RT, years	−0.5	−1.6 to 0.6	.381
Total RT dose to tumor, Gy	0.0	−1.0 to 1.1	.964
VP shunt	−5.0	−12.9 to 2.9	.217
Tumor location‡	2.7	−9.9 to 15.2	.680
Tumor diameter, cm‡	−1.6	−4.4 to 1.1	.251
Histology			.608
Glioma	—
Medulloblastoma/PNET	0.8	−34.3 to 35.8	.966
Germ cell tumor	1.9	−31.8 to 35.7	.911
Other§	14.8	−22.9 to 52.4	.441
Performance score ≤ 80‡║	−14.4	−22.7 to −6.0	.001
SES‡	−16.1	−46.4 to 14.1	.296
Race/ethnicity‡			< .001
White	—
Black	−16.0	−26.2 to −5.8	.002
Hispanic/Latino	0.3	−9.2 to 9.9	.946
Other¶	16.5	3.7 to 29.2	.011
IQ test type			< .001
Leiter	—
Woodcock-Johnson	13.4	6.1 to 20.7	< .001
Wechsler	3.9	−2.3 to 10.0	.218

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

^*Of the patients who underwent CSI, 13 were excluded from the model because of missing data on covariates.

^†Beta = slope.

^‡Data were missing for tumor location (n = 1), tumor diameter (n = 3), performance score (n = 7), SES (n = 1), and race/ethnicity (n = 2).

^§Other histology category includes choroid plexus carcinoma (n = 3), ganglioneuroblastoma (n = 1), epidermoid (n = 1), and undetermined (n = 1).

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

^¶Other race category includes Asian (n = 5) and American Indian (n = 1).