The effect of obsessive-compulsive symptoms and perfectionism on partial hospitalization program treatment trajectories

By definition, obsessions are intrusive thoughts that lead to the drive to engage in repetitive behaviors to manage distress (American Psychological Association [APA], 2022). Although often the target of treatment, obsessive-compulsive symptoms (OCS) can also interfere with treatment, as fear of uncertainty encourages avoidance of behavioral change, limiting the ability to obtain corrective information that could decrease OCS (Davis et al., 2020). To date, most studies have focused on how OCS impacts treatment outcomes among patients receiving specialized treatment for obsessive-compulsive disorder, suggesting that more severe OCS is associated with worse treatment outcomes (Kyrios et al., 2015; Keeley et al., 2008; Steketee et al., 2019). In contrast, far less is known about the role of OCS in broader, transdiagnostic treatment settings, where patients present with heterogeneous primary diagnoses but may still experience clinically meaningful OCS. Understanding whether and how OCS predict treatment response in these settings may help clarify their transdiagnostic influence on treatment engagement and recovery. A transdiagnostic factor that may be particularly relevant to understanding variability in treatment response among individuals with OCS is perfectionism. Perfectionism is defined as the need to strive for success in all aspects of life (Jiang et al., 2025; Shafran et al., 2002) and is associated with poor treatment outcomes in transdiagnostic care (Blatt & Zuroff, 2005; Zuroff et al., 2000). Given that perfectionism and OCS are associated with poorer treatment outcomes than those without these characteristics, combined they may lead to treatment disengagement due to (1) avoidance of treatment tasks driven by obsessive fear of failure, (2) emotional exhaustion due to compulsive attempts to engaging in treatment perfectly, and (3) lack of skills generalization across contexts due to cognitive rigidity (Pinto et al., 2011). These maladaptive behaviors, in turn, may lead to self-critical beliefs and distressing emotions that hinder treatment response (Hewitt & Flett, 1990). As such, those with both high OCS and greater perfectionism may represent a subset of patients that do not benefit from transdiagnostic treatment. In contrast, individuals with high OCS but low perfectionism may experience some benefit in treatment, as they may be less likely to rigidly evaluate their performance in treatment and therefore may be more willing to engage in therapeutic skills. Likewise, individuals with high perfectionism but low OCS may also experience some benefit, as perfectionistic striving may encourage greater adherence to treatment expectations. Further understanding the role of perfectionism and OCS on symptom trajectories will enable identification of treatment targets in transdiagnostic treatment programs.