Differentiating "types" of treatment dropout: Nonstarters in an RCT of prolonged exposure versus sertraline

Despite effective interventions for posttraumatic stress disorder (PTSD), many patients prematurely drop out. Differentiating "types" of dropout at various stages of treatment may improve our ability to predict and prevent attrition. Using data from a doubly randomized preference trial, this study examined patient dropout prior to treatment and compared these "nonstarters" with treatment starters and in-treatment dropouts. Patients (N = 200) with chronic PTSD were randomized to "choice" (prolonged exposure [PE] or sertraline) or "no choice" (re-randomized to PE or sertraline) and received up to 10 weeks of treatment. Overall dropout rate was 33.0% (n = 66). A substantial minority were nonstarters (n = 19; 28.8%). Relative to patients who began treatment, nonstarters reported less severe PTSD symptomatology (p = .03, d = 0.57) and were less likely to have received their preferred treatment (p < .001). These differences remained even when comparing nonstarters to patients that began treatment but eventually dropped out. Differences in beliefs (i.e., perceived credibility) toward one treatment versus the other were also linked to pretreatment dropout. Reasons underlying dropout likely differ during various treatment stages. Better understanding risk factors for types of dropout may inform strategies to boost engagement and retention, ultimately improving patient outcomes.