An evaluation of the effectiveness of a Transdiagnostic Bibliotherapy Program for anxiety and related disorders: results from two studies using a benchmarking approach

Anxiety and related disorders are common and cognitive behavior therapy (CBT) has been demonstrated to be an effective treatment for these disorders. However, patients face many barriers to accessing this treatment. Remote delivery of treatment using bibliotherapy-administered CBT (BCBT) has the potential to increase accessibility to evidence-based treatment for patients with anxiety and related disorders. This study investigated the effectiveness of a transdiagnostic BCBT intervention in two open trials. While the BCBT intervention in both studies were identical, the first study was unguided (i.e., no clinician support provided), and the second study was guided (i.e., patients were provided with brief clinician support via telephone). Twenty-three participants with mixed anxiety disorders completed the first Study (unguided treatment) and results exhibited significant reductions on the primary outcome measure with within-group effect sizes of d = 1.29 (95% CI 0.64–1.91) at post-treatment and d = 1.52 (95% CI 0.84–2.15) at 3-month follow up. Forty-one participants with various anxiety and related disorders completed Study 2 (guided intervention) and results were similar to Study 1 with large within-group effect sizes seen at post-treatment (d = 0.95; 95% CI 0.49–1.40) and 3-month follow up (d = 0.87; 95% CI 0.41–1.31). In both studies participants found the intervention to be highly acceptable, and benchmarking analyses indicated that the outcomes were largely consistent with those of controlled trials. These are the first studies to investigate the effectiveness of a transdiagnostic BCBT program for the treatment of anxiety and related disorders and the results demonstrate preliminary support for this treatment methodology