Determining Reliable Cognitive Change after Epilepsy Surgery: Development of Reliable Change Indices and Standardized Regression‐based Change Norms for the WMS‐III and WAIS‐III

Abstract

Summary:Purpose: Reliable change indices (RCIs) and standardized regression-based (SRB) change scores norms were established for the recently revised Wechsler Adult Intelligence Scale-III (WAIS-III) and Wechsler Memory Scale-III (WMS-III) in patients with complex partial seizures. Establishment of such standardized change scores can be useful in determining the effects of epilepsy surgery on cognitive functioning independent of test-retest artifacts including practice effects.Methods: Forty-two nonoperated-on adult patients with complex partial seizures (primarily of temporal lobe onset) were administered the WMS-III and WAIS-III on two occasions (mean 7-month interval). All patients were receiving stable antiepileptic drug (AED) treatment at both testings. RCI and SRB change scores were calculated. Confidence interval cutoff scores (90% and 80%) and standardized regression equations were calculated for each of the WAIS-III and WMS-III Primary Indices and individual subtests. Age, gender, education, testretest interval, preoperative test performance, seizure onset, and seizure duration were predictor variables for the SRB equations.Results: Test-retest reliabilities for the WAIS-III and WMS-III Primary Indices were within acceptable ranges, although considerable individual subtest variability was found. Preoperative performance was the single largest contributor to each of the predictive regression equations. Age, gender, education, seizure onset, and seizure duration contributed modest variance to several of the regression equations.Conclusions: We calculated both RCI and SRB change score indices for the recently revised Wechsler instruments. These formulas help control for test-retest methodologic artifacts and provide a standardized method with which to examine both individual and group level cognitive change after epilepsy surgery.

Neuropsychological Outcome after Deep Brain Stimulation in the Ventral Capsule/Ventral Striatum for Highly Refractory Obsessive-Compulsive Disorder or Major Depression

“…Neuropsychological change scores were computed for every patient, including corrections for practice effects and test-retest reliability [11]. Average practice effects for each test were obtained from published data with similar test-retest intervals, where possible.…”

Effect of invasive EEG monitoring on cognitive outcome after left temporal lobe epilepsy surgery

“…While change scores revealed greater decrements in naming and working memory among patients who underwent invasive monitoring, these score changes did not exceed the recommended cutoffs for identifying clinically meaningful cognitive change using RCIs. [14][15][16] RCIs are a preferred method for assessing cognitive change after epilepsy surgery, because they adjust for methodologic artifacts (e.g., imperfect test reliability, measurement error, practice effects) that simple change scores do not take into account. As such, these methods have become commonplace for assessing cognitive change among adults who undergo epilepsy surgery.…”

The prediction of Change: Normative neuropsychological trajectories

“…Meaningful change is typically determined when an observed difference score exceeds a specified confidence interval set around the mean of the expected change score. These procedures are increasingly being used in outcomes research such as epilepsy surgery Hermann et al, 1996Hermann et al, , 1999Martin et al, 2002;Sawrie et al, 1996;Seidenberg et al, 1998), cardiac procedures (Andrew, Baker, Bennetts, Kneebone, & Knight, 2001;Bruggemans, van de Vijver, & Huysmans, 1999;Collie, Darby, Falleti, Silbert, & Maruff, 2002;Kneebone, Andrew, Baker, & Knight, 1998;Lehrner et al, 2005; M. S. Lewis, Maruff, Silbert, Evered, & Scott, 2006), traumatic brain injury (Dikman et al, 1999;Ferland, Ramsay, Engeland, & O'Hara, 1998;McCrea et al, 2005;Temkin, Heaton, Grant, & Dikmen, 1999), post-operative cognitive dysfunction (Farag, Chelune, Schubert, & Mascha, 2006;M. Lewis, Maruff, & Silbert, 2004;Maze & Todd, 2007;Murkin, 2001), and aging Ivnik et al, 1999;Knight, McMahon, Skeaff, & Green, 2007;Raymond, Hinton-Bayre, Radel, Ray, & Marsh, 2006;Sawrie, Marson, Boothe, & Harrell, 1999;Tombaugh, 2005).…”