Abstract
Background/Aim:: In adolescents with low birth weight, specific deficits in cognitive abilities have been reported. For practical purposes it is customary to estimate IQ by using short forms in larger studies. If few tests are used and some of them tap into specific difficulties in these adolescents, IQ estimates may be artificially low compared to controls. The aim of this study was to compare the estimated IQ of two short forms of the WISC-III in adolescents with low birth weight and controls.
Design/methods: At age14, two groups of adolescents with low birth weight (54 prematures with birth weight < 1500 g (VLBW), and 60 small for gestational age born at term (SGA)) were compared to 83 controls with normal birth weight at term. IQ was estimated using four subtests from WISC-III: arithmetics and vocabulary from the verbal subscales and picture arrangement and block design from the performance scales ( Kaufman 1976) or by using two subtests: vocabulary and block design (Sattler 1992). Execpt for vocabulary, these subtests are associated with perceptual and spatial abilities.
Results: Both ways of estimating IQ resulted in significantly lower scores in the VLBW group than the SGA and the control group (p< 0.001). The score on vocabulary was similar in all groups, the VLBW group scored lower on the three other subtests than the two other groups. Estimating IQ by four subtests resulted in a reduction of 8.2 points in the VLBW group, 3.7 in the SGA group and 2.5 in the controls.
Conclusion: Estimates of IQ in VLBW adolescents are influenced by the choice of short forms of WISC-III. Using several subtests that load on perceptual and spatial abilities may indicate a level of intellectual functioning in these adolescents that may be too low. Caution is therefor warranted when using short forms of IQ tests.
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Kulseng, S., Skranes, J., Vik, T. et al. 139 Estimate Scores of Iq in Adolescents with Low Birthweight. The Choice of Shortforms Make A Difference. Pediatr Res 56, 487 (2004). https://doi.org/10.1203/00006450-200409000-00162
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DOI: https://doi.org/10.1203/00006450-200409000-00162