Introduction

Is the Problem the Solution: Evaluating Idiosyncratic Treatment Outcomes in a Transdiagnostic Youth Sample

Child and adolescent psychopathology is common and impairing, with approximately 17.4% of youth in the United States receiving a diagnosis of a mental, behavioral, or developmental disorder by age 8 years (Cree et al., 2018). Moreover, it is common for differing forms of psychopathology to co-occur in youth (Ghandour et al., 2019). The American Psychology Association (APA) has advocated for increased use of evidence-based practices to provide the best available treatments for youth with psychopathology (American Psychological Association [APA], 2006).

Evidence-based practice (EBP) is a term that has been defined in numerous ways, but often refers to assessment or treatment practices that represent the integration of the best available research with clinical expertise in the context of patient characteristics, culture, and preferences (APA, 2002; APA, 2005).

Studies have found that EBPs sometimes outperform usual care in community settings; for instance, 58% of randomly selected youth would have better treatment outcomes after EBP than those receiving usual care (Weisz et al., 2013). However, oftentimes the reverse is true and EBPs fail to outperform usual care in community settings (Southam-Gerow et al., 2010; Morgenstern et al., 2001; Westen et al., 2004). Given this mixed evidence, many clinicians are hesitant to incorporate EBPs into their practice (Hunsley & Mash, 2007; Jensen-Doss & Hawley, 2010; Weisz et al., 2006; Southam-Gerow, 2003).

A transdiagnostic, modular approach to psychotherapy may help reduce this hesitancy, as this approach has shown greater consistency, flexibility, and efficacy in treating youth mental illness (Evans et al., 2020; Leichsenring & Salzer; 2014; Weisz et al., 2012). Indeed, Evans and colleagues (2020) found that modular, transdiagnostic psychotherapy is significantly associated with fewer post-treatment diagnoses when compared to usual care (Evans et al., 2020). The need for transdiagnostic and principle-based approaches to treatment has also increased due to the reclassification of mental disorders from a global set of descriptors, based on theoretical concepts, to a more atheoretical, empirically derived and narrowly construed criteria that has led to a substantial increase in the total number and co- occurrence of disorders (Barlow et al., 2020). A transdiagnostic, modular format to treatment has also shown the most consistently favorable pattern across multiple outcomes and measurement schedules (Evans et al., 2020). Transdiagnostic approaches may also yield longer lasting benefits regarding comorbid disorders since they target underlying vulnerability and maintenance factors across multiple groups instead of focusing on risk factors common in one condition (Bentley et al., 2017; Garcia-Escalera et al., 2020).

The Unified Protocols for Transdiagnostic Treatment of Emotional Disorders in Children and Adolescents (UP-C and UP-A, respectively; Ehrenreich-May et al., 2018) are a developmentally appropriate treatment for emotional disorders in children and adolescents based on a transdiagnostic theoretical model (Barlow et al., 2020; Barlow et al., 2018). The UP-C/A uses techniques from cognitive-behavioral therapy, such as psychoeducation, cognitive reappraisal, behavioral activation, exposure, relapse prevention, motivational enhancement, and mindfulness techniques to treat emotional disorders in youth (Ehrenreich-May, 2018). The UP- C/A is designed to address common mechanisms that account for high comorbidity of emotional disorders and has several advantages over other transdiagnostic, evidence-based practices. For instance, transdiagnostic treatments that target symptoms of diagnoses or diagnostic categories through a modular system may contain an excessive number of modules and require complicated algorithms to address comorbid symptoms (Chorpita & Weisz, 2009; Weisz et al., 2012).

However, as a principle-driven, transdiagnostic intervention, the UP-C/A has the potential to reduce clinician burden and to address comorbid diagnoses by targeting the underlying and shared mechanisms of disorders as opposed to employing specific modules for specific diagnoses (Kennedy et al., 2020). There is considerable research demonstrating the effectiveness of the UP-C/A in ameliorating youth anxiety and depression symptoms across the intervention (Trosper et al., 2009; Queen et al., 2014). Moreover, the UP-C/A has been found to outperform randomized waitlist-controlled conditions in symptom severity at mid-treatment (Ehrenreich-May et al., 2017). Evidence suggests that the UP-C may be as efficacious and may produce greater gains in emotion regulation compared to an anxiety-specific intervention (Kennedy et al., 2018).

Patient-focused, evidence-based idiographic assessments offer valuable contributions to transdiagnostic EBP, such as the UP-C/A, as they can monitor, predict, and evaluate patient progress and quantitatively measure treatment effectiveness (Camara et al., 2000). These types of client-guided assessments can also help identify therapeutic targets/goals and give rise to individualized discussions that build rapport between the clinician and client (Weisz et al., 2011). Idiographic assessments may also be more culturally relevant because the client can highlight culture-specific problems that may not be included in standardized EBPs (Wasil et al., 2021; Weisz et al., 2011). Incorporation of adaptive, idiographic assessments and measurement feedback systems (Ng & Weisz, 2016) in clinical interventions has become more common due to the increased emphasis on patient preferences to guide the trajectory of treatment (Gondek et al., 2016). Past work has found that youth treated at sites where clinicians receive weekly feedback on symptom improvement and treatment acceptability improve faster than youth treated at sites where clinicians do not receive weekly feedback (Bickman et al., 2011).

One particularly promising idiographic assessment measure is the Top Problems assessment (TPA), which assesses the severity of problem-areas identified by the individual client (Herren et al., 2018; Weisz et al., 2011). The TPA is a client- guided assessment where the clinician works with the client to list three to five problems they would like to address in treatment. The client then rates the severity of each problem at every session throughout treatment (Evans et al., 2021; Herren, 2018). The TPA is unique in that it provides weekly feedback to the clinician on problem severity which can allow the clinician to modify treatment to best fit the needs of the client. Such idiographic, measurement informed care has been found to increase treatment effectiveness (Gondek et al., 2016). Assessment of client- identified problems through the TPA may provide richer information and further specificity about an intervention’s effectiveness beyond that of standardized, nomothetic assessments (Weisz et al., 2011).

There is a paucity of existing literature utilizing the TPA; however, past work has used the TPA to measure symptom improvement, sudden gains, and early treatment response in youth treatment outcomes (Milgram et al., 2021; Dour et al., 2013; Weisz et al., 2012). For instance, Dour and colleagues (2013) found that 20- 42% of participants experienced at least one sudden gain, defined as a rapid improvement in symptom severity, measured by both the TPA and nomothetic measures. The TPA has also been used to assess standard and modular arrangements of evidence-based treatment for depression, anxiety, and conduct problems in youth compared to usual care (Weisz et al, 2012). Early top problem improvement in the UP-C/A has also been linked to younger child age and higher parent cognitive flexibility (Milgram et al., 2021). While prior work has looked at early- improvement using the TPA, the current study is unique in that it offers a more nuanced understanding of symptom reduction by looking at multiple timepoints throughout a transdiagnostic intervention for youth (UP-C/A). Importantly, the TPA has been used to determine treatment effectiveness across various transdiagnostic treatment modalities like the Modular Approach to Therapy for Children (MATCH; Chorpita & Weisz, 2009), but no study, as yet, has examined the TPA across the entirety of the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders in Children and Adolescents (UP-C/A, Ehrenreich-May et al., 2018).