Predictors and moderators of treatment outcome from high- and low-intensity cognitive behavioral therapy for anxiety disorders: Association between patient and process factors, and the outcome from guided self-help, stepped care, and face-to-face cognitive behavioral therapy

The understanding of factors that are associated with the outcome from cognitive behavioral therapy (CBT) for anxiety disorders is limited. Identifying characteristics that are related to the treatment outcome can improve treatments and provide better criteria for matching of patients to treatments that they are likely to benefit from. This thesis investigates factors associated with the outcome from various formats of CBT for anxiety disorders, panic disorder and social anxiety disorder in particular. The thesis comprises three scientific articles that addressed the overall effect of self-help treatment, as well as study-level factors, patient characteristics, and factors related to the therapy process, as predictors and moderators of the treatment outcome from CBT provided as guided self-help, face-to-face treatment and stepped care. Methods: Paper I investigated the effectiveness of and factors associated with the outcome of self-help treatment for all anxiety disorders. The study sample comprised 56 studies with 82 comparisons of a self-help treatment to a no-treatment/placebo or another active treatment. The overall effectiveness of self-help treatment was investigated in two meta-analyses; one in which self-help was compared to a waiting list or placebo control group (n=56), and one in which self-help was compared to an active treatment (n=28). Potential study level predictors were investigated in subgroup analyses and meta-regression analyses. Papers II and III used data from a randomized controlled effectiveness trial: the “Assessment and Treatment- Anxiety in Children and Adults” (ATACA) study, which compared immediate face-to-face CBT (FtF-CBT) to a CBT-based Stepped Care treatment model for panic disorder and social anxiety disorder. The Stepped Care model comprised three steps: psychoeducation, Internet-delivered CBT (ICBT), and face-to-face CBT. The total study sample comprised 173 patients (69 with panic disorder and 104 with social anxiety disorder). All assessment and treatment was conducted by clinical staff in nine public mental health clinics Paper II investigated nonspecific predictors and moderators of guided self-help, stepped care, and manualized FtF-CBT for panic disorder and social anxiety disorder from the complete study sample in the ATACA study (N=173). The putative predictors and moderators were investigated in multiple regression analyses. Paper III investigated the working alliance and therapist competence as predictors of the treatment outcome of face-to-face CBT for panic disorder and social anxiety disorder. The study sample comprised the 88 patients (33 with panic disorder and 55 with social anxiety disorder) who were randomized to the immediate FtF-CBT in the ATACA study. The association between the alliance, competence, and outcome was investigated using analyses of covariance and multiple regression analyses. Results: The results from Paper I indicated a medium- to large-effect size (g=0.78) that favors self-help treatment over a wait list-placebo control group, and a small effect size that favors face-to-face treatment over self-help (g=-0.20). The subgroup analyses and metaregressions indicated that Internet- and computer-based self-help programs delivered in community settings were associated with superior outcomes to those of self-help delivered as bibliotherapy or conducted in clinical settings. Furthermore, the outcome from the self-help treatment was similar to the outcome from non-specific conventional treatment but poorer than face-to-face CBT. The results from Paper II indicated that the same patient characteristics generally appear to be associated with the treatment outcome for CBT provided in low- and high-intensity formats. The patients with lower social functioning, more severe anxiety disorder consequences, and a comorbid cluster C personality disorder had significantly less improvement from the treatment. Furthermore, having a comorbid anxiety disorder was associated with a better treatment outcome among the patients with panic disorder but not for the patients with social anxiety disorder. Comorbid depression was associated with a better outcome when the patients were treated with guided self-help but not immediate FtF-CBT. The results from Paper III indicated that the alliance and competence are independent processes that contribute to the treatment outcome in different phases of the therapy. Higher competence ratings in the early therapy sessions and higher alliance ratings in the late therapy sessions were both associated with a better treatment outcome. Conclusions: The findings from this thesis indicate that Internet-based self-help treatment can be an important, potentially cost-effective, low threshold supplement to other evidencebased treatments for anxiety disorders. Moreover, it identifies several factors related to the structure and format of the treatment, patient characteristics and factors related to the therapy process that is associated with the outcome of treatment. Thus, this thesis may have important implications for implementation of evidence-based treatment to clinical care. This includes how self-help treatment can be structured and organized, how to identify patients that are likely to improve from treatment, and issues related to the training and supervision of the therapists