Associations between ICD-11 trauma-related disorders, treatment engagement and outcomes of substance-use treatment

Purpose The co-occurrence of post-traumatic stress disorder (PTSD) and substance use disorder (SUD) presents significant challenges for substance-use treatment services. There is mixed evidence, however, regarding how this presentation impacts on treatment engagement and outcome, and no existing research has examined this in the context of ICD-11 PTSD and Complex PTSD (CPTSD). This study aims to then examine associations between trauma-related disorders, treatment engagement and substance use outcomes – in the context of the ICD-11 diagnostic system. Design/methodology/approach In all, 72 individuals entering substance use treatment were recruited into this prospective cohort study. Data on treatment engagement were obtained from medical records and was available for all participants. Data on trauma-related symptoms and substance use outcomes were obtained via interviews undertaken at baseline and three-month follow-up (n = 40, follow-up rate = 55.6%). Findings Both PTSD- and CPTSD-related functional impairment were associated with higher levels of treatment engagement; however, no trauma-related symptoms demonstrated associations to premature disengagement from treatment. There was little evidence of reliable changes in trauma-related symptoms or substance use outcomes. Changes in CPTSD- but not PTSD-related symptoms were associated with changes in psychological dependence. Neither PTSD- nor CPTSD-related symptom changes were associated with changes in recent substance use. Individuals presenting with comorbid trauma-related symptoms are no more likely to disengage from treatment; however, those with greater functional impairment related to their symptoms will likely require higher levels of service. Further research is required to determine the added benefit of trauma-focussed treatment in addition to substance-use treatment alone. Originality/value This study provides the first examination of how symptoms of ICD-11 PTSD and Complex PTSD change during substance use treatment. The results of this study can inform the expansion of trauma-informed and trauma-focussed treatment approaches embedded in substance use treatment.