Measuring Trauma Exposure: Count Versus Variety of Potentially Traumatic Events in a Binational Sample.

Traumatic event checklists typically ask respondents to indicate whether they have experienced particular types of potentially traumatic events (PTEs) and then sum these endorsements to gauge cumulative trauma exposure. However, the sum of these endorsements indicates the variety of PTEs respondents have experienced rather than the count of exposure events. The main objective of the present study was to explore the association between PTE count and variety to examine assumptions regarding the use of traumatic event checklists to measure cumulative trauma exposure. The limited empirical research suggests that count and variety are strongly associated; however, there may be variation in magnitude concerning whether participants' environments confer an increased or decreased risk of exposure. We present Life Event Checklist data from a large sample of Mexican and U.S. participants (n = 1,820), which allowed us to compare reports of count and variety. Count and variety were strongly correlated, Kendall's tau-b = .74, such that count accounted for 54.6% of the variance in variety. A negative binomial regression analysis revealed that this association was moderated by county and municipio homicide rate, used as a proxy for violent crime, but not by natural disaster history. Variety was more strongly associated with scores on the Posttraumatic Stress Checklist for DSM-5, Kendall's tau-b = .26, than was PTE count, Kendall's tau-b = .22, Fisher's z = -8.04, p < .001. Although there are challenges in estimating PTE counts, the present findings suggest that PTE variety is not a good proxy for cumulative trauma exposure.