BACKGROUND: Privacy and data security concerns are frequently cited barriers to the adoption of internet-based interventions. Allowing anonymous use may reduce these barriers, but whether anonymity affects clinical outcomes is unclear.
OBJECTIVE: This study compared an internet-based self-help intervention for social anxiety offering platform-level anonymity with a conventional account-based version and investigated whether anonymity preferences were associated with outcomes.
METHODS: In this partially randomized patient preference trial, 452 adults with heightened social anxiety symptoms were assigned by randomization or preference to an anonymous or account-based 8-week unguided cognitive behavioral self-help program. Assessments occurred at baseline, post-treatment, and 24-week follow-up. The primary outcome was social anxiety severity, analyzed with mixed-effects models testing superiority of the account-based version.
RESULTS: Participants showed substantial reductions in social anxiety symptoms (within-group d = -0.81 to -0.62). The account-based version was not superior in either arm. The post-treatment between-version difference was small (d = 0.09, 95% CI: -0.17 to 0.35) and robust across sensitivity analyses. Secondary outcomes including depressive symptoms and mental quality of life also improved. Improvements were maintained at follow-up. Most participants preferred the account-based version. Exploratory analyses provided no robust evidence of outcome differences by preference or preference match.
DISCUSSION: The platform-level anonymous intervention was not outperformed by the conventional account-based program. Because the trial was powered for superiority and included no non-active control, formal equivalence and absolute efficacy remain to be established. Within these limits, the findings provide no evidence that the privacy-protective, account-free design came at the cost of reduced symptom improvement.
