The purpose of the analyses was to compare lifetime prevalence of traumatic events and PTSD between the cocaine dependent cases recruited from treatment and the community-based participants. We also examined lifetime prevalence of PTSD among those who have experienced a traumatic event (i.e., conditional risk for PTSD). Analyses were conducted separately for males and females because of the known gender differences in rates of drug dependence, exposure to violence, and PTSD (Breslau, 2009; Compton et al., 2005; Kandel et al., 1997). The prevalence rate ratio (PRR) was calculated to compare lifetime prevalence between the cases and community-based participants (Rothman and Greenland, 1998; Zocchetti et al., 1995). There was no correction for multiple testing. In addition, regression analyses were performed to assess the predictors of conditional risk for PTSD and number of traumatic events, whereby number of events refers to the 15 different types of events queried. All analyses were performed using the Statistical Package for the Social Sciences (SPSS, 2008).
