Experiences of service users receiving peer support in mental health services: Qualitative findings from the international UPSIDES trial.

Although peer support is increasingly used in mental health services worldwide, service users' experiences have been studied mostly in high-income countries. The current study examined service users' experiences of peer support in the UPSIDES Trial, delivered across diverse cultural and resource contexts, including high, middle and low-income countries. Semi-structured interviews were conducted with 33 service users across six study sites (Germany [two sites], Uganda, Tanzania, Israel, and India) and analyzed using thematic analysis to identify patterns in participants' experiences. To capture diverse perspectives, service users were purposively sampled based on pre-post changes in social inclusion and personal recovery, with participants randomly selected from the top and bottom 20% ('high' and 'low' responders). Four themes emerged: (1) adaptable settings and intervention flexibility; (2) 'active ingredients' such as mutuality, reciprocity, and role-modeling; (3) positive intra-personal, inter-personal, and behavioral outcomes; and (4) barriers, including mismatches, unmet expectations, unclear boundaries and challenges to continuity. The study highlights shared relational elements of peer support alongside context-specific adaptations. Findings reinforce its value as a complementary, person-centred service with global relevance, while pointing to challenges including improving matching, reducing dropout, and clarifying expectations. Site-specific aspects are discussed, offering insights for global implementation.