Within-treatment clinical markers of dropout risk in integrated treatments for comorbid PTSD and alcohol use disorder*

Background: Integrated interventions for comorbid posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) are effective, but many patients prematurely drop out from treatment. Little is known about withintreatment risk factors for dropout, limiting the ability during therapy to identify patients at risk for attrition. Methods: We examined measures assessing PTSD (PTSD Checklist for DSM-5; PCL-5), alcohol use (Substance Use Inventory; SUI), and patient satisfaction (Client Satisfaction Questionnaire; CSQ-8) as potential within-treatment markers of dropout risk, administered to 110 veterans in a randomized clinical trial of integrated exposure therapy versus integrated coping skills therapy for comorbid PTSD + AUD. Hierarchical Cox proportional hazard models with dropout status as the endpoint assessed effects of PCL-5, SUI, and CSQ-8 on dropout risk, and whether effects differed by treatment modality. Results: A significant interaction between treatment and changes in alcohol use was observed (HR = 2.86, p = .007), where between-session alcohol use was positively associated with dropout hazard rate for those receiving integrated exposure therapy (HR = 2.34, p = .004), but not coping skills therapy (HR = 0.73, p = .19). Specifically, an increase of one drink consumed per day in the interval since last assessment (typically 2?3 weeks) was associated with a 5-fold increase in dropout hazard rate. Conclusions: The findings provide preliminary evidence of detectable within-treatment markers of dropout during integrated treatment for PTSD + AUD. Study of within-treatment indicators proximal to dropout may help identify at-risk patients and inform timely strategies to boost retention.