Prevalence, correlates, and clinical features of delayed-onset posttraumatic stress disorder in a nationally representative military sample

Since its inclusion in the Diagnostic and Statistical Manual of Mental Disorders, there has been skepticism over the validity
of delayed-onset posttraumatic stress disorder (PTSD). Paucity of research on the correlates and the clinical consequences
of delayed-onset PTSD have historically added to this skepticism. The objective of this study was to address an important
gap in the literature by examining the prevalence, the correlates, and the clinical consequences of delayed-onset PTSD using
data from a large epidemiological survey.

Data were drawn from the Canadian Community Health Survey-Canadian Forces Supplement (N = 8,441), a cross-sectional epidemiological survey of mental health in the Canadian Forces. Logistic regressions were used
to identify correlates of delayed onset. Cox regressions were used to examine the impact of delayed onset on symptom duration.

The prevalence of delayed-onset PTSD in this Canadian population was less than 1%. Delayed-onset cases accounted for 8.5%
of all PTSD cases. Experiencing trauma in early childhood, experiencing a repeated trauma, and serving in the land troops
were all associated with greater likelihood of developing delayed-onset PTSD. Delayed onset, after controlling for important
sociodemographic, military, and clinical variables, was associated with greater symptom duration.

The phenomenon of delayed-onset PTSD, albeit uncommon, does exist. Certain trauma characteristics may increase the risk for
developing delayed-onset PTSD. Delayed onset may be associated with more chronic forms of this disorder.