PURPOSE: Many people with mental illness experience self-stigma and stigma-related stress and struggle with decisions whether to disclose their condition to others. The peer-led Honest, Open, Proud (HOP) group program supports them in their disclosure decisions. In randomized controlled trials, HOP has shown positive effects on self-stigma and stigma stress on average. This study examined individual predictors of HOP outcomes and tested the hypothesis that stigma stress reduction at the end of HOP mediates positive HOP effects at follow-up.

METHODS: Six RCTs were included with data at baseline, post (after the HOP program) and at 3- or 4-week follow-up. Baseline variables were entered in meta-regression models to predict change in self-stigma, stigma stress, depressive symptoms and quality of life among HOP participants. Mediation models examined change in stigma stress (post) as a mediator of HOP effects on self-stigma, depressive symptoms, and quality of life at follow-up.

RESULTS: More shame at baseline, and for some outcomes reduced empowerment, predicted reduced HOP effects on stigma stress, self-stigma, depressive symptoms, and quality of life. Younger age was related to greater improvements in stigma stress after the HOP program. Stigma stress reductions at the end of HOP mediated positive effects on self-stigma, depressive symptoms and quality of life at follow-up.

CONCLUSION: Participants who are initially less burdened by shame may benefit more from HOP. Stigma stress reduction could be a key mechanism of change that mediates effects on more distal outcomes. Implications for the further development of HOP are discussed.