Background: Symptoms of post-traumatic stress disorder (PTSD) have been reported even years after the terrorist attacks of September 11, 2001 (9/11).
Methods: We used screening tools to assess the prevalence of probable PTSD in 9/11-exposed firefighters at two time points, within 6 months of 9/11 (baseline) and 3-4 years post-disaster (follow-up).
Results: Five thousand six hundred fifty-six individuals completed assessments at both times. 15.5% reported probable PTSD post-9/11, 8.6% at baseline and 11.1% at follow-up, on average 2.9 (SD 0.5) years later. Analyses revealed that nearly half of all probable PTSD occurred as delayed onset (absent baseline, present follow-up). Compared with the resilient group (no probable PTSD at either time), probable PTSD at baseline, and delayed onset at follow-up were each associated with concomitant functional impairment (OR 19.5 and 18.9), respectively.
Conclusion: Similar percentages of firefighters met criteria for baseline and delayed onset probable PTSD at follow-up, years later. Both were associated with substantial functional impairment. Early risk identification could provide opportunities for mental health interventions before symptoms compromise work and social relationships.