TABLE 2

Comparisons of WISC-III Scores Between Preterm and Term Children at 12 Years' Chronological Age

IQPreterm (N = 375)Term (N = 111)All Children Included, Adjusted Mean Difference or OR (95% CI)Children With Severe Brain Injury Excluded, Adjusted Mean Difference or OR (95% CI)a
nMean (SD)nMean (SD)
WISC-III
    Verbal IQ36990.8 (18.9)111103.9 (16.0)−10.8 (−14.3 to −7.3)b−8.9 (−12.0 to −5.7)b
    Performance IQ36786.8 (17.9)111103.1 (15.7)−14.6 (−18.1 to −11.1)b−12.7 (−15.9 to −9.5)b
    FSIQ36687.9 (18.3)111103.8 (15.7)−13.7 (−17.1 to −10.3)b−11.7 (−14.7 to −8.7)b
    Verbal comprehension36992.3 (18.6)108104.3 (15.4)−9.9 (−13.4 to −6.5)b−8.1 (−11.2 to −4.9)b
    Perceptual organization36786.9 (17.7)111102.9 (15.8)−14.6 (−18.1 to −11.2)b−12.8 (−16.0 to −9.6)b
    Freedom of distractibility36789.9 (16.8)110101.7 (16.4)−10.1 (−13.5 to −6.8)b−8.3 (−11.5 to −5.1)b
    Processing speed36194.5 (19.9)108108.5 (16.7)−12.0 (−15.9 to −8.0)b−10.0 (−13.7 to −6.3)b
Subtest scaled score
    Information3688.7 (3.8)11010.7 (3.6)−1.6 (−2.3 to −0.9)b−1.3 (−2.0 to −0.6)b
    Similarities3698.9 (3.5)11111.1 (3.1)−1.8 (−2.5 to −1.2)b−1.5 (−2.1 to −0.9)b
    Arithmetic3667.7 (3.4)11110.3 (3.6)−2.4 (−3.1 to −1.6)+−2.0 (−2.7 to −1.3)b
    Vocabulary3658.8 (3.8)11010.7 (3.0)−1.5 (−2.2 to −0.8)b−1.2 (−1.9 to −0.6)b
    Comprehension3687.8 (3.9)11110.3 (3.3)−2.1 (−2.8 to −1.3)b−1.7 (−2.4 to −1.0)b
    Digit span3698.4 (3.2)11010.0 (3.0)−1.3 (−1.9 to −0.6)b−1.0 (−1.6 to −0.4)b
    Picture completion3688.0 (3.4)11110.1 (2.9)−2.0 (−2.7 to −1.3)b−1.7 (−2.4 to −1.0)b
    Coding3658.4 (3.8)11010.6 (3.4)−1.7 (−2.4 to −0.9)b−1.4 (−2.1 to −0.6)b
    Picture arrangement3677.9 (3.8)11110.5 (3.5)−2.3 (−3.1 to −1.6)b−2.0 (−2.7 to −1.3)b
    Block design3687.7 (3.9)11111.2 (3.7)−3.1 (−3.9 to −2.3)b−2.7 (−3.5 to −2.0)+
    Object assembly3677.0 (3.5)1119.7 (3.0)−2.4 (−3.1 to −1.7)b−2.1 (−2.8 to −1.5)b
    Symbol search3639.1 (4.3)10912.4 (3.5)−3.0 (−3.8 to −2.1)b−2.6 (−3.4 to −1.7)b
WISC-III, n/N(%)
    Verbal IQ < 7042/369 (11.4)1/111 (0.9)14.0 (1.9 to 105.1)c11.1 (1.4 to 87.6)c
    Performance IQ < 7061/367 (16.6)0
    FSIQ < 7052/366 (14.2%)0
  • Adjustment for male gender, maternal age < 20 years, maternal years of education, minority status, and single-parent household.

  • a Severe brain injury: grade 3 and 4 IVH, PVL, grade 2 and above ventriculomegaly.

  • b P < .005.

  • c P < .05.