Supplementary materials to "Worry postponement from the metacognitive perspective: A randomized waitlist-controlled trial"

Background: Pathological worry is associated with appraisals of worrying as uncontrollable. Worry postponement (WP) with a stimulus control rationale appears to be effective in non-clinical samples. However, preliminary research in participants with generalized anxiety disorder (GAD) does not support its efficacy in reducing negative metacognitions or worry. The aim of this study was to investigate the efficacy of WP with a metacognitive rationale. Method: Participants with GAD (n = 47) or hypochondriasis (HYP; n = 35) were randomly assigned to either an intervention group (IG) or waitlist (WL). The IG received a two-session long WP intervention aiming at mainly reducing negative metacognitions concerning uncontrollability of worrying. Participants were instructed to postpone their worry process to a predetermined later time during the six days between the two sessions. Participants completed questionnaires of negative metacognitions and worry at pre-assessment, post-assessment, and follow-up. Results: We observed a significant Time*Group interaction for negative metacognitions and worry. Post-hoc analyses on the total sample and separately for GAD and HYP revealed significantly lower worry scores in the treated GAD sample compared to the WL, representing the only significant effect. In the GAD group, pre-post-effect sizes were small for negative metacognitions and large for worry. Effects persisted to a four-week follow-up. Conclusion: WP with a metacognitive rationale seems to be effective in reducing worry in participants with GAD. The effectiveness for HYP seems limited, possibly due to the small sample size.