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

Aim: 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. Design: Prospective longitudinal 16-month cohort study of new syringe exchange registrants enrolled in a parent study of methods to improve treatment engagement. Setting: Data were collected in a research van next to mobile syringe exchange distribution sites in Baltimore, Maryland. Participants: Male and female (n=162) injecting drug users (IDUs) registered for syringe exchange. Measurements: 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). Findings: 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. Conclusions: 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.