Comparison of baseline-referenced versus norm-referenced analytical approaches for in-theatre assessment of mild traumatic brain injury neurocognitive impairment

Abstract

Primary objective: To examine differences between the baseline-referenced and norm-referenced approaches for determining decrements in Automated Neuropsychological Assessment Metrics Version 4 TBI-MIL (ANAM) performance following mild traumatic brain injury (mTBI).

Research design: ANAM data were reviewed for 616 US Service members, with 528 of this sample having experienced an mTBI and 88 were controls.

Methods and procedures: Post-injury change scores were calculated for each sub-test: (1) normative change score = in-theater score – normative mean and (2) baseline change score = in-theater score – pre-deployment baseline. Reliable change cut-scores were applied to the change and the resulting frequency distributions were compared using McNemar tests. Receiver operator curves (ROC) using both samples (i.e. mTBI and control) were calculated for the change scores for each approach to determine the discriminate ability of the ANAM.

Main outcomes and results: There were no statistical differences, p < 0.05 (Bonferonni-Holm corrected), between the approaches. When the area under the curve for the ROCs were averaged across sub-tests, there were no significant differences between either the norm-referenced (0.65) or baseline-referenced (0.66) approaches, p > 0.05.

Conclusions: Overall, the findings suggest there is no clear advantage of using the baseline-referenced approach over norm-referenced approach.

Keywords:

• mTBI
• military
• ANAMA
• neurocognitive
• baseline
• normative

Declaration of interest

This report was supported by the US Navy Bureau of Medicine and Surgery Project #255. The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense or the U.S. Government. Approved for public release; distribution is unlimited. This study protocol was reviewed by the Navy Experimental Diving Unit Institutional Review Board and determined to not qualify as human subject research in compliance with all applicable Federal regulations governing the protection of human subjects. LT Haran and MAJ Dretsch are military service members. This work was prepared as part of their official duties. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.