Effectiveness of Transdiagnostic Internet-Delivered Cognitive Behavioral Therapy for Symptoms of Adjustment Disorder: A Longitudinal Observational Study in a Routine Online Care Setting

Background : Trials of disorder-specific Internet-delivered cognitive-behavioral therapy (ICBT) for Adjustment Disorder (AD) show moderate effect sizes but may have limited scalability in routine care settings, where clients present with a range of concerns. Transdiagnostic ICBT, which addresses common emotional and behavioral concerns irrespective of diagnosis, could address the need for effective and scalable treatments for symptoms of AD. Objective: This study aimed to evaluate the effectiveness of a transdiagnostic ICBT course for patients with high AD symptoms, and to investigate predictors of treatment outcomes, and treatment satisfaction. Methods: 793 participants received a therapist-guided, transdiagnostic ICBT course. The study measured changes in AD symptoms from pre-treatment to post-treatment to 3-month follow-up using the Adjustment Disorder – New Module 8 (ADNM-8). Results: The prevalence of high AD symptoms (defined as a score >23 on the ADNM-8) was 54.8% at pre-treatment. The study found large reductions in AD symptoms from pre-treatment to post-treatment ( d  = 1.29, 95% CI [1.13, 1. 45]) and from pre-treatment to the 3-month follow-up ( d  = 1.67, 95% CI [1.49, 1.85]). These effect sizes were comparable to those found in previous ICBT trials of AD-specific treatments. Approximately 70% of participants scored below clinical cut-off for high AD symptoms at post-treatment, and 79 % met this criterion at follow-up. Engagement in treatment and post-treatment satisfaction were similar between individuals with high AD symptoms and those without, with the majority (76.9%) completing four or more lessons and 81.7% reporting overall satisfaction. Conclusions: The findings suggest that transdiagnostic ICBT is an effective and acceptable treatment for AD symptoms, with results comparable to those of AD-specific interventions. The high prevalence of AD symptoms and stressful life events among participants in a routine care setting underscores the importance of early identification of individuals with high AD symptoms.