B – 144 Base Rate of Invalid Performance Among Blast-Exposed Active-Duty Military Personnel

Abstract Objective This study examined the base rate of invalid performance among active-duty military service members (SMs) with blast exposure on neuropsychological testing and whether these rates differ between blast-only and blast+PTSD groups. Method Retrospective analysis of a large military dataset (N=1,010) referred for outpatient neuropsychological evaluations following deployment was conducted (Puente et al., 2020). After removing duplicates, 880 distinct individuals remained, with 546 reporting blast exposure. Invalid performance was defined as failing ≥2 performance validity tests (PVTs). Excluding SMs with fewer than four PVTs (n=492), the final sample included Blast Only (n=187) and Blast+PTSD (n=305). Most were male (98.37%) and White (85.55%), with a mean age of 25.85 years and 12.47 years of education. Results Invalid performance rates were 10.2% (19/187, 95% CI [6.6–15.2]) in Blast Only, 11.8% (36/305, 95% CI [8.6–15.9]) in Blast+PTSD, and 11.6% (57/492, 95% CI [9.0–14.7]) overall. A chi-square analysis indicated no significant difference (χ2[1]=0.037, p=.847). Conclusion Overall rate (11.6%) is consistent with prior research in SMs receiving routine care (12.8%) but differs from other studies, including SMs, likely due to differences in methodology and evaluation context, e.g., clinical vs. disability (32-50%;Denning & Shura, 2019). Consistent with prior research (Jones et al., 2012), comorbid PTSD did not significantly increase invalid performance rates compared to blast exposure alone, suggesting factors may be more relevant to performance validity in this population. Limitations include the retrospective design and predominantly male sample. Future research should explore additional factors like time since injury, medication effects, and other comorbidities that may influence performance validity in military populations.