Brief online cognitive behavioural intervention for dysfunctional worry related to the covid-19 pandemic: Pre-specified interim results from a randomised trial
Objective: To investigate if a brief self-guided, online cognitive behavioural intervention can reduce the degree of dysfunctional worry related to the covid-19 pandemic.Design: Randomised waiting list controlled trial.Setting: Swedish general population. Participants: Self-referred adults reporting daily uncontrollable worry about covid-19 and its possible consequences. The trial aims to include 670 participants in total. Here we present the results of a pre-specified interim analysis on data from the first 300 randomised participants. Intervention: A brief (3-week) self-guided, online cognitive behavioural intervention targeting dysfunctional worry related to the covid-19 pandemic. Main outcome measure: A covid-19 adapted version of the self-rated Generalised Anxiety Disorder 7-item scale assessed at baseline, week 1, week 2 and week 3 (primary endpoint). Results: The main pre-specified intention-to-treat analysis indicated significant reductions in covid-19-related worry for the intervention compared to waiting list (=2.64, Z=4.02, p<.001), corresponding to a medium effect size (bootstrapped d=0.69 [95% CI; 0.43 to 0.95]). Improvements were also seen on several secondary measures, including mood, daily functioning and intolerance of uncertainty. Participant satisfaction was high. No serious adverse events were recorded.Conclusions: A brief digital and easily scalable self-guided psychological intervention can significantly reduce dysfunctional worry and associated behavioural symptoms related to the covid-19 pandemic. The full trial will provide more precise estimates of the magnitude of the effects, their long-term durability, and potential adverse effects. Trial registration: ClinicalTrials.gov registration ID: NCT04341922, registered on April 10 2020 before inclusion of the first participant.