WHAT HAPPENED TO THE WAITING LIST GROUP? AN ANALYSIS OF THE OUTCOMES OF THE WAITING LIST PARTICIPANTS FROM AN INTERNET-DELIVERED INTERVENTION FOR DEPRESSION: A RANDOMISED-CONTROLLED TRIAL
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Authors: Phelim Tierney, Ladislav Timulak, Derek Richards
Keywords: CBT, depression, online, intervention
Abstract: Objectives: The objective of the present study was to evaluate the effectiveness of an online intervention for reducing depression symptoms on the wait-list group of an RCT trial investigating the same intervention. Design: Internet-delivered Cognitive-Behavioural Therapy (CBT) interventions are establishing themselves as an effective, accessible and acceptable low-intensity intervention for depression. The present study represented part of an RCT trial investigating the efficacy of an 8 week internet-delivered CBT (iCBT) intervention for adults with depression symptoms, and this study investigated the waiting list group independently. Analyzing the wait-list group independently as part of the trial facilitated the analysis of spontaneous remission effects on the outcome. Methods: Participants (n=92) were self-referred from a national charity representing people with depression, and self-reported mild to moderate depression symptoms as rated by the BDI-II; which constituted the primary outcome measure. Measures were administered at signup, pre-treatment, post-treatment and 3-month follow up. Data were analyzed using the Intention to Treat (ITT) model, using a Maximum Likelihood algorithm to account for missing data. Results: A significant reduction of the primary outcome measure, depression symptoms, was observed at post-treatment, with a large effect size (d = 0.7), and the outcomes were maintained at follow up. Conclusions: The study has demonstrated the effectiveness of the Space from Depression internet-delivered intervention, demonstrating significant and reliable improvements in depression symptoms. Investigation of the waiting list group independently suggests that outcomes are not due to spontaneous remission. Implications of the research for advancing the design and implementation of internet-delivered interventions are discussed.