Convergent Validity and Test-Retest Reliability of the Blast Exposure Threshold Survey Among Army Special Operations...

The Blast Exposure Threshold Survey (BETS) is a self-report questionnaire assessing lifetime generalized blast exposure value (GBEV). This study examined GBEV convergent validity and GBEV and BETS item-by-item test-retest reliability.

In this prospective-cohort study, Army Special Operations Forces (ARSOF) trainers and trainees completed the BETS and a demographic intake form one week before Special Forces Advanced Urban Combat (SFAUC) training. BETS was also administered 1 and 8 weeks post-training. Spearman's rho correlations assessed convergent validity from pre-SFAUC time points. A two-way mixed effect, consistency, single rater intraclass correlation coefficient (ICC3,1 [95%CI]) and percent agreement analyzed test-retest reliability for post-SFAUC time points.

Forty-one participants (17.1% trainers; mean age: 32.8 [SD 5.7] y), and 13 participants (7.7% trainers; mean age: 33.2 [SD 5.6] y; 49.7 [SD 6.5] days between test-retest) were included in convergent validity and test-retest analyses, respectively. GBEV displayed moderate convergent validity with all proxy measures of blast exposure (rho-range=0.595-0.672, P<.001 all). GBEV displayed moderate test-retest reliability (ICC3,1=0.576 [95% CI 0.160-0.818]). Individual weapon categories were poor-moderate (ICC3,1-range=0.070-0.766). Items within each section displayed poor-excellent test-retest reliability (ICC3,1range=-0.145-0.843). The difference and average from both post-SFAUC timepoint were strongly correlated indicating worse recall with higher GBEV (n=13, rho=0.907, P<.001).

GBEV has strong convergent validity but poor-moderate test-retest reliability. Caution should be used when interpreting BETS results, especially in populations experiencing excessive blast exposures. However, our small sample size limits the interpretability of the results.