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Reexamining the effects of epilepsy surgery on IQ in children: Use of regression-based change scores

Published online by Cambridge University Press:  27 August 2003

Elisabeth M.S. Sherman*
Affiliation:
Department of Psychology, British Columbia's Children's Hospital, Vancouver, British Columbia, Canada Department of Psychology, University of British Columbia, Vancouver, British Columbia, Canada
Daniel J. Slick
Affiliation:
Department of Psychology, British Columbia's Children's Hospital, Vancouver, British Columbia, Canada
Mary B. Connolly
Affiliation:
Division of Neurology, British Columbia's Children's Hospital, Vancouver, British Columbia, Canada Division of Neurology, University of British Columbia, Vancouver, British Columbia, Canada
Paul Steinbok
Affiliation:
Division of Neurosurgery, Section of Surgery, British Columbia's Children's Hospital, Vancouver, British Columbia, Canada Division of Neurosurgery, Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
Roy Martin
Affiliation:
University of Alabama at Birmingham Epilepsy Center, Birmingham, Alabama
Esther Strauss
Affiliation:
Department of Psychology, University of Victoria, Victoria, British Columbia, Canada
Gordon J. Chelune
Affiliation:
Mellen Center, Cleveland Clinic, Cleveland, Ohio
Kevin Farrell
Affiliation:
Division of Neurology, British Columbia's Children's Hospital, Vancouver, British Columbia, Canada Division of Neurology, University of British Columbia, Vancouver, British Columbia, Canada
*
Reprint requests to: E.M.S. Sherman, Ph.D., Department of Psychology, British Columbia's Children's Hospital, K3-122, 4480 Oak Street, Vancouver, British Columbia V6H 3V4, Canada. E-mail: esherman@cw.bc.ca

Abstract

Prior studies have found no adverse effects of pediatric epilepsy surgery on IQ. However, empirical techniques such as regression models, designed to account for confounding factors such as practice effects and test–retest reliability and able to provide a standardized method for evaluating outcome, have not been used in studying change after pediatric epilepsy. The goal of this study was to demonstrate the regression technique while empirically measuring the effect of epilepsy surgery on IQ in a group of pediatric patients. Predictors of retest IQ (e.g., baseline IQ, retest interval, demographics, epilepsy severity) were evaluated in a control group with intractable seizures (N = 23) assessed twice with the WISC–III. The resulting equation was used to evaluate IQ changes in a second group of children who underwent epilepsy surgery (N = 22). In controls, baseline IQ was a strong predictor of retest IQ. Number of AEDs was inversely related to retest IQ. Based on the control regression, four children (18%) in the surgical sample obtained significantly higher than expected postsurgical IQ scores and one child (5%) obtained a lower than expected IQ score. This study demonstrates that regression-based techniques yield informative estimates on outcome and may be an improvement over prior methods of measuring change after pediatric epilepsy surgery. (JINS, 2003, 9, 879–886.)

Type
Research Article
Copyright
Copyright © The International Neuropsychological Society 2003

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