Transdiagnostic Internet treatment for anxiety disorders: A randomized controlled trial Nickolai Titov a, * , Gavin Andrews a , Luke Johnston a , Emma Robinson b , Jay Spence b a School of Psychiatry, University of New South Wales, Sydney, Australia b Clinical Psychologist, St Vincent’s Hospital, Sydney, Australia article info Article history: Received 23 March 2010 Received in revised form 13 May 2010 Accepted 18 May 2010 Keywords: Internet cognitive behavioural therapy (iCBT) Randomized controlled trial (RCT) Anxiety Transdiagnostic Treatment Internet abstract Clinician-guided Internet-based cognitive behavioural therapy (iCBT) programs are clinically effective at treating specific anxiety disorders. The present study examined the efficacy of a transdiagnostic Internet- based cognitive behavioural treatment (iCBT) program to treat more than one anxiety disorder within the same program (the Anxiety Program). Eighty six individuals meeting diagnostic criteria for general- ized anxiety disorder (GAD), panic disorder, and/or social phobia were randomly assigned to a treatment group, or to a waitlist control group. Treatment consisted of CBT based online educational lessons and homework assignments, weekly email or telephone contact from a clinical psychologist, access to a moderated online discussion forum, and automated emails. An intention-to-treat model using the baseline-observation-carried-forward principle was employed for data analyses. Seventy-five percent of treatment group participants completed all 6 lessons within the 8 week program. Post-treatment data was collected from 38/40 treatment group and 38/38 control group participants, and 3-month follow-up data was collected from 32/40 treatment group participants. Relative to controls, treatment group participants reported significantly reduced symptoms of anxiety as measured by the Generalized Anxiety Disorder e 7 Item, Social Phobia Screening Questionnaire, and the Panic Disorder Severity Rating Scale e Self Report Scale, but not on the Penn State Worry Questionnaire, with corresponding between-groups effect sizes (Cohen’s d) at post-treatment of 0.78, 0.43, 0.43, and 0.20, respectively. The clinician spent a total mean time of 46 min per person over the program, participants rated the procedure as moderately acceptable, and gains were sustained at follow-up. Modifications to the Anxiety program, based on post- treatment feedback from treatment group participants, were associated with improved outcomes in the control group. These results indicate that transdiagnostic programs for anxiety disorders may be successfully administered via the Internet. Crown Copyright Ó 2010 Published by Elsevier Ltd. All rights reserved. Introduction Anxiety disorders are common, affecting 1 in 7 adults. By themselves, these conditions result in considerable disability and distress (Australian Bureau of Statistics, 2008). However, anxiety disorders frequently co-occur, and comorbidity is associated with increased distress, disability, and service utilization (Andrews, Slade, & Issakidis, 2002). Anxiety disorders can be effectively treated with disorder- specific treatment plans (Andrews et al., 2003) or, as indicated by an emerging literature, transdiagnostic or unified programs that target the common elements and symptoms across disorders (Barlow, Allen, & Choate, 2004). The potential benefits to patients and clinicians of requiring only one transdiagnostic program compared to numerous disorder-specific programs are consider- able. For example, patients with different disorders may be treated with the same program, thus reducing waiting list times for disorder-specific programs, while patients with comorbid anxiety disorders or depression may concurrently learn to manage multiple disorders. Recent meta-analyses of transdiagnostic treatment for the anxiety disorders (Norton & Price, 2007), and for anxiety combined with depression (McEvoy, Nathan, & Norton, 2009), while based on a relatively small number of studies, indicate that transdiagnostic treatment can result in similar outcomes to disorder-specific treatment. Despite the existence of effective disorder-specific or trans- diagnostic treatments, fewer than 50% of people with anxiety seek treatment and less than one quarter receive evidence-based * Correspondence to: Dr Nickolai Titov, CRUFAD at St Vincent’s Hospital, 299 Forbes Street, Darlinghurst, NSW 2010, Australia. Tel.: þ61 2 8382 1732; fax: þ61 2 8382 1721. E-mail address: nickt@unsw.edu.au (N. Titov). Contents lists available at ScienceDirect Behaviour Research and Therapy journal homepage: www.elsevier.com/locate/brat 0005-7967/$ e see front matter Crown Copyright Ó 2010 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.brat.2010.05.014 Behaviour Research and Therapy 48 (2010) 890e899