Effectiveness and cost-effectiveness of a self-guided internet intervention for social anxiety symptoms in a general population sample : randomized controlled trial

Background: Many people are accessing digital self-help for mental health problems, often with little evidence of effectiveness.Social anxiety is one of the most common sources of mental distress in the population and many people with symptoms do not seek help for what represents a significant public health problem. Objective: Two group randomized controlled trial conducted in England between 11th May 2016 and 27th June 2018. Adults with social anxiety symptoms who were not receiving treatment for social anxiety were recruited using online advertisements. All participants had unrestricted access to usual care and were randomized in a 1:1 ratio to either a web-based unguided self-help intervention based on cognitive-behavioural principles, or to a waiting list control group. All outcomes were collected through self-report online questionnaires. The primary outcome was the change in 17-item self-report Social Phobia Inventory (SPIN-17) score from baseline to 6 weeks using a linear mixed-effect model that used data from all timepoints (6 weeks, 3, 6, 12 months). Methods: Two group randomized controlled trial conducted in England between 11th May 2016 and 27th June 2018. Adults with social anxiety symptoms who were not receiving treatment for social anxiety were recruited using online advertisements. All participants had unrestricted access to usual care and were randomized in a 1:1 ratio to either a web-based unguided self-help intervention based on cognitive-behavioural principles, or to a waiting list control group. All outcomes were collected through self-report online questionnaires. The primary outcome was the change in 17-item self-report Social Phobia Inventory (SPIN-17) score from baseline to 6 weeks using a linear mixed-effect model that used data from all timepoints (6 weeks, 3, 6, 12 months). Results: 2212 participants were randomized. Six were excluded from analyses as ineligible. Of the 2116 eligible randomized participants (mean age 37 years, 80% women), 70.1% (1484/2116) had follow-up data available for analysis, and 56.9% (1205/2116) had data on the primary outcome, although attrition was higher in the intervention arm. At 6 weeks the mean (95% CI, P value) adjusted difference in change in SPIN-17 score in the intervention group compared to control, was -1.94 (-3.13 to -0.75, P=0.0014), a standardised mean difference effect size of 0.2. The improvement was maintained at 12 months. Given the high drop-out, sensitivity analyses explored missing data assumptions and were consistent with the primary analysis finding. The economic evaluation demonstrated cost-effectiveness with a small health status benefit and a reduction in health service utilisation. Conclusions: For people with social anxiety symptoms who are not receiving other forms of help, this study suggests that an online self-help tool based on cognitive behavioural principles can provide a small improvement in social anxiety symptoms compared with no intervention, although drop-out rates were high. Clinical Trial: ClinicalTrials.gov NCT02451878. https://clinicaltrials.gov/ct2/show/NCT0245187