Table 4.

Multivariate Models of WIAT Reading (n = 65)

Covariate*	Parameter	Estimate	SE	P
Intercept	α0	84.26	4.33	.0006†‡
No. of surgeries (1 v > 1)	α1	12.05	3.52	.0008†§
Diagnosis to treatment (> 1.5 v ≤ 1.5 months)	α2	5.16	3.33	.12§
GH at diagnosis (> 10 v ≤ 10 ng/mL)	α3	−2.16	3.32	.52§
Tumor (infratentorial v supratentorial)	α4	11.21	2.56	< .0001†§
Slope	β0	0.37	0.069	.60§
No. of surgeries (1 v > 1)	β1	−0.23	0.066	.0006†§
Diagnosis to treatment (> 1.5 v ≤ 1.5 months)	β2	−0.22	0.061	.0004†§
GH at diagnosis (> 10 v ≤ 10 ng/mL)	β3	0.20	0.060	.0012†§

Abbreviations: WIAT, Wechsler Individual Achievement Test; CRT, conformal radiation therapy; GH, growth hormone; Diagnosis to treatment, the time duration between diagnosis and CRT.

^*Parameters are for the model: WIAT reading = α₀ + α₁X₁ + α₂X₂ + α₃X₃ + α₄X₄ + (β₀ + β₁X₁ + β₂X₂ + β₃X₃) × time where X₁ is the number of surgeries (= 1 for 1 surgery and 0 for > 1 surgery), X₂ is the months from diagnosis to treatment (= 1 if > 1.5 months and 0 if ≤ 1.5 months), X₃ is growth hormone at CRT diagnosis (= 1 if > 10 and 0 if ≤ 10), and X₄ is tumor location (= 1 if infratentorial and 0 if supratentorial).

^†P < .05.

^‡Compared with a normative mean of 100.

^§Group comparisons based on the categorical split for the covariate.