This study is unique in its use of a case-cohort sampling design. Cases were cocaine dependent participants recruited from chemical dependency treatment settings and this group was compared to a cohort recruited from the same community. We examined the types of traumatic events and risk of PTSD after experiencing a traumatic event (conditional risk of PTSD) in cocaine dependent cases and community-based cohort. Overall, the pattern of traumatic events in this study is consistent with previous reports (Breslau et al., 1998; Kessler et al., 1995). What differs is the magnitude of the violence and traumatic events experienced by both cocaine dependent cases recruited from treatment and individuals in the community-based cohort.
