Determining Reliable Cognitive Change Following Epilepsy Surgery: Development of Reliable Change Indices (RCI) and Standardized Regression-Based (SRB) Change Norms for the WMS-3 and WAIS-3.
Abstract number :
3.102
Submission category :
Year :
2001
Submission ID :
274
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
R.C. Martin, Ph.D., Neurology, University of Alabama at Birmingham, Birmingham, AL; S.M. Sawrie, Ph.D., Neurology, University of Alabama at Birmingham, Birmingham, AL; M. Mackey, B.A., Neurology, University of Alabama at Birmingham, Birmingham, AL; R.C. K
RATIONALE: Within the past few years development of empirically-based statistical methodologies for determining cognitive change within a epilepsy surgery context have been proposed. Recent studies have supported the use of RCI and SRB techniques in providing standardized methodologies for establishing the direction and magnitude of cognitive change following epilepsy surgery. The objective of the present study was to calculate RCI and SRB change scores for the newly revised Wechsler Adult Intelligence Scale (WAIS-3) and Wechsler Memory Scale (WMS-3) for use in determining statistically meaningful cognitive change following epilepsy surgery.
METHODS: Thirty-five unoperated adult patients with complex partial seizures (primarily of temporal lobe origin) were administered the WAIS-3 and WMS-3 on two occasions (mean 6 month interval). All patients were on stable antiepilepsy drug treatment and free of major psychopathology. RCI and SRB change scores were calculated to correct for test-retest artifacts of practice, regression-to-the-mean, and test reliability. The SRB calcuation helped to identify and adjust for the effects of variables such as age and education. 90% confidence interval cuttoff scores and regression equations were calculated for each of the WAIS-3 and WMS-3 Primary Indices.
RESULTS: Test-retest reliablity for all WAIS-3 Indices was above .90 while WMS-3 reliablility scores ranged from .70 (Auditory Recognition) to .91 (Immediate Memory). Utilizing a modified practice adjusted RCI formula 90% CIs ranged from [underline] + [/underline]6.0 (Full Scale IQ) to [underline] + [/underline]18 (Auditory Recognition). Preoperative test performance was the largest contributor to each of the regression equations predicting postoperative performance. Age, seizure onset, and seizure duration were contributors to the Auditory Recognition equation. No other demographic or clinical variable contributed to any of the other regression equations.
CONCLUSIONS: The present study calculated both RCI and SRB change score indices for the newly revised Wechsler instruments. These empirically-based methods provide standardization when assessing cognitive change, help control for test-retest artifacts, and can be reliably employed when assessing the effects of epilepsy surgery on cognitive functioning in patients with temporal lobe epilepsy.
Support: Epilepsy Foundation of America Young Investigator Award presented to the Senior Author.