These examples highlight the conditional risk of PTSD, that is, the rate of PTSD among individuals who have experienced at least one traumatic event, whereas the general population prevalence reported by Kessler et al. (1995) is for all individuals. Cottler et al. (1992) examined rates of trauma and PTSD in the general population and found that alcohol and drug users were almost twice as likely to experience a traumatic event compared to non-users. This study also provides a direct comparison of conditional risk of PTSD, where drug users were three times more likely to meet criteria for PTSD than non-users (Cottler et al., 1992).
