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; n = 28), intervention without therapist support (unguided; n = 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 d = 0.96). The intervention was effective against waiting list irrespective of whether it was provided in a guided (between-group d = 0.90) or unguided format (between-group d = 1.07) with sustained results at the 7-week follow-up. Reduction in worry mediated improvement in daily functioning (between-group d = 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 r = 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. • This trial showed that a brief online intervention was effective in reducing degree of excessive worry. • The intervention reduced worry both in guided- and unguided format. • Reductions in excessive worry mediated improvements in daily functioning.