A-104 Meta-Analysis of Neuropsychological Intra-Individual Variability in Mild- and Moderate/Severe-Traumatic Brain Injury

Objective Intra-individual variability (IIV) applied to cognition refers to scatter of performances at the individual level. This study meta-analyzed research that examined consistency (i.e., within-task) IIV in mild-traumatic brain injury (mTBI) and moderate/severe-traumatic brain injury (msTBI) compared to normal controls. Method Using PRISMA-guided search parameters, eight databases within the EBSCO network as well as ProQuest Dissertations & Theses were searched for studies comparing cognitive IIV between TBI and control samples. Random-effects modeling was used for all analyses. Hedge’s g was used as the index of combined effect size, and Q and I2 were evaluated for heterogeneity analyses. Results This study was a part of a broader meta-analysis looking at IIV across all clinical samples. The initial search strategy yielded 2,962 results, which were reduced to 87 studies for final inclusion. This meta-analysis included 12 studies (mTBI: k = 9, 64 effect sizes; msTBI: k = 5, 10 effect sizes). Meta-analysis resulted in a significant combined effect size across all TBI studies (g = 0.45, Q = 23.49, I2 = 53.17). When stratifying for TBI severity, msTBI samples yielded a greater combined effect size (g = 0.66, Q = 10.70, I2 = 62.61) than mTBI (g = 0.39, Q = 10.49, I2 = 23.74). Highest degree of between-study heterogeneity was noted in the msTBI studies. Conclussions Broad TBI as well as mTBI and msTBI studies yielded significant combined effect sizes, consistently showing elevated cognitive IIV in TBI samples compared to healthy controls. The combined effect size approximately doubled from mTBI to msTBI. This provides evidence that consistency-based IIV is sensitive and possibly specific to neurologic/pathologic burden. This supports prior literature framing IIV as an index of neurological health.