Prospective effects of traumatic event re-exposure and post-traumatic stress disorder in syringe exchange participants


Correspondence to: Jessica M. Peirce, Johns Hopkins University School of Medicine, Mason F. Lord, 6th Floor East, 5200 Eastern Avenue, Baltimore, MD 21224, USA. E-mail:



Determine the effect of traumatic event re-exposure and post-traumatic stress disorder (PTSD) symptom severity on proximal drug use and drug abuse treatment-seeking in syringe exchange participants.


Prospective longitudinal 16-month cohort study of new syringe exchange registrants enrolled in a parent study of methods to improve treatment engagement.


Data were collected in a research van next to mobile syringe exchange distribution sites in Baltimore, Maryland.


Male and female (n = 162) injecting drug users (IDUs) registered for syringe exchange.


Traumatic event re-exposure was identified each month with the Traumatic Life Events Questionnaire. PTSD symptoms were measured with the Modified PTSD Symptom Scale–Revised, given every 4 months. Outcome measures collected monthly were days of drug use (heroin, cocaine) and drug abuse treatment-seeking behavior (interest, calls to obtain treatment, treatment participation).


Each traumatic event re-exposure was associated with about 1 more day of cocaine use after accounting for the previous month's cocaine use [same month adjusted B, standard error = 1.16 (0.34); 1 month later: 0.99 (0.34)], while PTSD symptoms had no effect. Traumatic event re-exposure increased interest in drug abuse treatment [same month adjusted odds ratios with 95% confidence intervals = 1.34 (1.11–1.63)] and calling to obtain treatment [same month 1.58 (1.24–2.01); 1 month later 1.34 (1.03–1.75)]. Each 10% increase in PTSD symptom severity was associated with persistent increased interest in treatment [same month 1.25 (1.10–1.42); 1 month later 1.16 (1.02–1.32); 2 months later 1.16 (1.02–1.32)] and calling to obtain treatment [same month 1.16 (1.02–1.32)]. Neither traumatic events nor PTSD symptoms were associated with participants receiving treatment.


Becoming exposed again to traumatic events among injecting drug users is associated with an increase in cocaine use up to 1 month later, but drug use is not related to post-traumatic stress disorder symptoms. Both traumatic event re-exposure and post-traumatic stress disorder symptoms predict drug abuse treatment-seeking behavior for up to 2 months.