Normative data and validation of a regression based summary score for assessing meaningful neuropsychological change

Abstract

Reliable detection and quantification of longitudinal cognitive change are of considerable importance in many neurological disorders, particularly to monitor central nervous system effects of disease progression and treatment. In the current study, we developed normative data for repeated neuropsychological (NP) assessments (6 testings) using a modified standard regression-based (SRB) approach in a sample that includes both HIV-uninfected (HIV–, N = 172) and neuromedically stable HIV-infected (HIV+, N = 124) individuals. Prior analyses indicated no differences in NP change between the infected and uninfected participants. The norms for change included correction for factors found to significantly affect follow-up performance, using hierarchical regression. The most robust and consistent predictors of follow-up performance were the prior performance on the same test (which contributed in all models) and a measure of prior overall NP competence (predictor in 97% of all models). Demographic variables were predictors in 10–46% of all models and in small amounts; while test–retest interval contributed in only 6% of all models. Based on the regression equations, standardized change scores (z scores) were computed for each test measure at each interval; these z scores were then averaged to create a total battery change score. An independent sample of HIV– participants who had completed 8 of the 15 tests was used to validate an abridged summary change score. The normative data are available in an electronic format by e-mail request to the first author. Correction for practice effects based on normative data improved the consistency of NP impairment classification in a clinically stable longitudinal cohort after baseline.

Keywords:

• Normative data
• Longitudinal studies
• Regression
• Regression change score
• Standard regression-based change score
• Practice effect

Acknowledgments

Request of electronic normative data: e-mail [email protected] and specify “request of change normative data” in the subject head of the e-mail. The data will also be available from the HNRC website: http://hnrc.hivresearch.ucsd.edu/

This study was supported by the HIV Neurobehavioral Research Center* (HNRC supported by Center Award MH 62512 from the National Institute of Mental Health, NIMH), the CNS HIV Anti-Retroviral Therapy Effects Research** (CHARTER) study (supported by Award N01 MH22005 from the National Institutes of Health), the MH 58076 grant, and Brain Sciences postdoctoral fellowship at the University of New South Wales. Lucette A. Cysique is supported by the Brain Sciences postdoctoral fellowship from the University of New South Wales, Sydney, Australia.

*The San Diego HIV Neurobehavioral Research Center (HNRC) group is affiliated with the University of California, San Diego, the Naval Hospital, San Diego and the Veterans Affairs San Diego Healthcare System, and it includes: Director: Igor Grant; Co-Directors: J. Hampton Atkinson, Ronald J. Ellis, and J. Allen McCutchan; Center Manager: Thomas D. Marcotte; Naval Hospital San Diego: Braden R. Hale (P.I.); Neuromedical Component: Ronald J. Ellis (P.I.), J. Allen McCutchan, Scott Letendre, Edmund Capparelli, Rachel Schrier; Neurobehavioral Component: Robert K. Heaton (P.I.), Mariana Cherner, Steven Paul Woods; Neuroimaging Component: Terry Jernigan (P.I.), Christine Fennema-Notestine, Sarah L. Archibald, John Hesselink, Jacopo Annese, Michael J. Taylor, Neurobiology Component: Eliezer Masliah (P.I.), Ian Everall, Cristian Achim; Neurovirology Component: Douglas Richman (P.I.), David M. Smith; International Component: J. Allen McCutchan (P.I.); Developmental Component: Ian Everall (P.I.), Stuart Lipton; Clinical Trials Component: J. Allen McCutchan, J. Hampton Atkinson, Ronald J. Ellis, Scott Letendre; Participant Accrual and Retention Unit: J. Hampton Atkinson (P.I.), Rodney von Jaeger; Data Management Unit: Anthony C. Gamst (P.I.), Clint Cushman (Data Systems Manager), Daniel R. Masys (Senior Consultant); Statistics Unit: Ian Abramson (P.I.), Christopher Ake, Florin Vaida. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government.

**The CNS HIV Anti-Retroviral Therapy Effects Research (CHARTER) group is affiliated with the Johns Hopkins University; Mount Sinai School of Medicine; University of California, San Diego; University of Texas, Galveston; University of Washington, Seattle; and Washington University, St. Louis; it is headquartered at the University of California, San Diego and includes: Director: Igor Grant; Co-Directors: J. Allen McCutchan, Ronald J. Ellis, Thomas D. Marcotte; Center Manager: Donald Franklin; Neuromedical Component: Ronald J. Ellis (P.I.), J. Allen McCutchan, Terry Alexander; Laboratory, Pharmacology and Immunology Component: Scott Letendre (P.I.), Edmund Capparelli; Neurobehavioral Component: Robert K. Heaton (P.I.), J. Hampton Atkinson, Steven Paul Woods, Matthew Dawson; Virology Component: Joseph K. Wong (P.I.); Imaging Component: Christine Fennema-Notestine (P.I.), Terry L. Jernigan, Michael J. Taylor, Rebecca Theilmann; Data Management Unit: Anthony C. Gamst (P.I.), Clint Cushman; Statistics Unit: Ian Abramson (P.I.), Florin Vaida; Protocol Coordinating Component: Thomas D. Marcotte (P.I.), Rodney von Jaeger; Johns Hopkins University Site: Justin McArthur (P.I.), Mary Smith; Mount Sinai School of Medicine Site: Susan Morgello (Co-P.I.) and David Simpson (Co-P.I.), Letty Mintz; University of California, San Diego Site: J. Allen McCutchan (P.I.), Will Toperoff; University of Washington, Seattle Site: Ann Collier (Co-P.I.) and Christina Marra (Co-P.I.), Trudy Jones; University of Texas, Galveston Site: Benjamin Gelman (P.I.), Eleanor Head; and Washington University, St. Louis Site: David Clifford (P.I.), Muhammad Al-Lozi, Mengesha Teshome. The views expressed in this article are those of the authors and do not reflect the official policy or position of the United States Government.