Efficacy of a brief online intervention in reducing excessive worry and improving daily functioning: A randomized trial with mediation analysis.

Excessive worry is common among treatment-seeking individuals in primary care and has a negative impact on daily functioning, which may also lead to other mental health problems. The current study tested whether a worry-focused online intervention - provided in both a guided and an unguided format - was efficacious in reducing worry-related symptoms and if these effects were specifically linked to improvements in daily functioning. A total of 82 participants were randomized to intervention with therapist support (guided;  = 28), intervention without therapist support (unguided;  = 27) or to waiting list (n = 27). Results showed that the online intervention was more effective than waiting list in reducing worry at week 5 (between-group  = 0.96). The intervention was effective against waiting list irrespective of whether it was provided in a guided (between-group  = 0.90) or unguided format (between-group  = 1.07) with sustained results at the 7-week follow-up. Reduction in worry mediated improvement in daily functioning (between-group  = 0.58; indirect effect estimate = -1.06 [95 % CI: -1.76 to -0.51], 66 % mediated effect). The mediation effects were fairly robust to mediator-outcome confounding, with residual correlation values set to  = 0.3 in a sensitivity analysis. The results provide further evidence that it is beneficial to provide a low-threshold, easy access intervention to patients with excessive worry, irrespective of primary diagnosis. Clinical implications are discussed.