Reliability, practice effects, and change indices for Rao's brief repeatable battery

The role of cognitive impairment in multiple sclerosis is now widely recognized. However, there is a dearth of research on variability and practice effects of neuropsychological measures when repeated over time. The objective was to assess reliability and practice effects for Rao's Brief Repeatable Battery of neurophysiological tests and the Stroop Test, and to provide data for correction for variability and practice effects in serial assessments. In 54 healthy controls (34 women, mean age 38.3 +/- 9.1 years, mean education 12.9 +/- 3.3 years), the Brief Repeatable Battery and Stroop Test were administered 3 times with an 18-month interval. Reliability was assessed by intraclass correlation coefficient and practice effects by an analysis of variance with Bonferroni's correction for repeated measures. Test-retest reliability was from adequate to good on the Symbol Digit Modalities Test, the Stroop Test, and the Paced Auditory Serial Addition Test. The great majority of tests showed at least a moderate practice effects. Data for calculation of an individual's change in cognitive performance for each test of the Brief Repeatable Battery and the Stroop Test were provided. Our results provide relevant information for planning and interpreting longitudinal studies on cognition and cognitive rehabilitation in multiple sclerosis.