Using base rates of low scores to interpret the ANAM4 TBI-MIL battery following mild traumatic brain injury

Base rates of low ANAM4 TBI-MIL scores were calculated in a convenience sample of 733 healthy male active duty soldiers using available military reference values for the following cutoffs: 2nd percentile (2 SDs), 5th percentile, <10th percentile, and <16th percentile (1 SD). Rates of low scores were also calculated in 56 active duty male soldiers who sustained an mTBI an average of 23 days (SD = 36.1) prior. 22.0% of the healthy sample and 51.8% of the mTBI sample had two or more scores below 1 SD (i.e., 16th percentile). 18.8% of the healthy sample and 44.6% of the mTBI sample had one or more scores 5th percentile. Rates of low scores in the healthy sample were influenced by cutoffs and race/ethnicity. Importantly, some healthy soldiers obtain at least one low score on ANAM4. These base rate analyses can improve the methodology for interpreting ANAM4 performance in clinical practice and research.