Conditional probability of posttraumatic stress disorder in the Canadian Armed Forces: A longitudinal study

Posttraumatic stress disorder (PTSD) can be impacted by the type of trauma exposure. This is important to consider when evaluating the likelihood of having PTSD among Canadian veterans, which previous literature has not examined. The aim of this study was to: 1) Examine the prevalence and conditional probability of PTSD over a 16 year period by trauma type, differentiating by sex, and 2) Explore this relationship by worst trauma type.

We examined the prevalence of PTSD by sex among those with any exposure to 26 traumatic events, and used logistic regressions to examine trauma type and PTSD. The conditional probability of having PTSD over the 16-year follow-up period (2002-2018) and in the past year was calculated using population attributable fractions (PAFs). Identical analyses were used to examine the conditional probability of PTSD related to a self-reported 'worst event'.

Over the 16-year follow-up, we found that males showed higher conditional likelihood of developing PTSD from exposure to sexual trauma while females showed a higher conditional likelihood of developing PTSD from exposure to an accidentrelated trauma. For the probability of PTSD conditional on the worst event, accidentrelated or sexual trauma in females, and sexual and deployment-related trauma in males showed the highest PAF and strongest relationship.

This research supports differences in PTSD prevalence depending on the type of traumatic exposure. Importantly, different patterns of conditional probability of PTSD emerged by sex. These findings can provide important information for mental health providers within the military treating multiple traumas.