The aim of this randomized, two-arm, investigator initiated, multi municipal, parallel-group superiority trial is to compare the effect on self-reported personal recovery of the following interventions: (1) 10-week group-based peer support intervention "Paths to everyday life" (PEER) added to service as usual (SAU); and (2) SAU alone. The primary outcome is self-reported personal recovery at end of intervention. Secondary and exploratory measures include empowerment, quality of life, functioning, hope, self-efficacy, self-advocacy and social network. The investigators, hypothesize that the superiority of the PEER intervention will be applicable for secondary outcomes and exploratory measures at end of intervention so that improvement in empowerment, hope, self-efficacy, self-advocacy, social network, quality of life and functioning will be improved among participants allocated to the PEER intervention.

The "Paths to everyday life" (PEER) intervention is a newly developed community-based peer support intervention targeting persons with mental vulnerability and mental health difficulties. The development of the PEER intervention is conducted in a collaboration between the Peer partnership association and the Copenhagen Research Center for Mental Health (CORE), Recovery & Inclusion, Mental Health Center Copenhagen.

The PEER intervention is inspired from: Peer support groups in the MIND Leeds organization; Manuals for peer support services and peer training, which has shown positive effect on measures of personal recovery in RCTs; Practical guides to everyday life developed by consumers of mental health treatment in Denmark; and lived experiences of mental illness and recovery within the project group. The content of the ten group sessions is developed from themes identified in the CHIME (Connectedness; Hope; Identity; Meaning; Empowerment) framework as promoting the personal recovery process, as well as knowledge from systematic reviews and meta-analyses in the field focusing on the effect of peer support. The entire PEER intervention is described in a comprehensive manual and detailed instructions have been prepared for the volunteer peers to make it accessible and ensure similarity across the groups. The manual of the PEER intervention has been further developed in a pilot study of the 10 week group sessions in a qualitative evaluation (N=25) in the period Feb.-Sept. 2020 in the collaborative municipalities Copenhagen, Elsinore and Fredericia.

The PEER intervention consists of a 10-week group course and the opportunity of individual companionship to e.g. local activities in civil society, municipal social services, education, health and employment. It is mandatory for the participants to participate in an introductory meeting with the purpose of informing about the group process, the individual companionship and the RCT, so that participation in the intervention becomes the participants' own informed choice. The group sessions are delivered by two volunteer peers with their own experiental knowledge of mental vulnerability and personal recovery. The volunteer peers must complete a basic peer education to facilitate the group course and enter individual companionship. A fidelity scale is developed and used for biannual fidelity reviews to ensure intervention program adherence and continuous focus on program implementation and improvement.

The overall purpose of the PEER intervention is to find a way to live life in a meaningful, energizing way - despite still finding some things challenging. The aim is to form a constructive community through group sessions where exchanges of lived experiences, mutuality and opportunities for social network development can form. The investigators hypothesize, that the volunteer peers by sharing their own experiences with mental vulnerability and personal recovery can create trust and inspire the participants to safely share their own experiences. Additionally, that the volunteer peers by presenting group themes and by participating on an equal footing with the participants in the group exercises can contribute to the participants' experience of connectedness with others, as well as promote the participants self-esteem and belief in possibilities, dreams and aspirations to regain meaning in life circumstances, control and responsibility for own life.

The PEER intervention will be evaluated in a two armed randomized controlled trial. The primary hypothesis for the trial is that participants allocated to the PEER intervention added to service as usual (SAU) gain a significantly increased experience of self-reported personal recovery at end of intervention than participants who are allocated to SAU alone.

The PEER intervention is not expected to have any severe side effects. However, when trial recruitment and the intervention phase has ended, safety measures i.e. number of somatic and psychiatric hospitalization days, death, suicide and probable self-harm is obtained from the Danish central registers to examine any severe adverse effects during the intervention period.

The sample size and power calculations was conducted using PS Power and Sample Size Calculations software. With an allocation ratio of 1:1 and a minimum clinically relevant difference of 5, a power of 80% and a significance level of 0.05%, we need 284 participants, i.e. 142 in the intervention group and 142 in the control group in order to reject the null hypothesis that self-assessed personal recovery is equal in the control group and the PEER group. Data analyzes will be based on the intention-to-treat principle i.e. that data from all participants will be included corresponding to the group to which the participants have been allocated. In case of missing data, multiple multivariate imputations will be used.

Inclusion Criteria:

• Citizens using the municipal social service in the participating municipalities for support and assistance due to mental vulnerability and mental health difficulties, corresponding to the target group for §82 in the law of social service - i.e. citizens diagnosed with a mental illness and/or who is affected by mental dissatisfaction to a degree that limits the unfolding of life. Additionally, citizens who self-refer to the trial with similar mental health challenges.
• Are residents of collaborating municipalities at baseline.
• Can understand, speak, and read Danish.
• Are aged 18 years or older.
• Have given verbal and written consent to participate in the trial.

Exclusion criteria:

1. Citizens intoxicated by alcohol and/or other substances - if they according to the local coordinator's judgment cannot participate in the peer group, they are advised to contact professional help.
2. Citizens with specific suicide plans - if they according to the local coordinator's judgment cannot participate in the peer group, they are advised to contact professional help.

The individual participant data that support the findings in this article will be made available after de-identification, along with the statistical analysis plan, upon reasonable request from researchers who provide a methodologically sound proposal. To request access, proposals should be directed to the corresponding author. Data requestors will need to sign a data access agreement to gain access to the data. The register-based data cannot be provided on request because it is hosted by Statistics Denmark. The data was only accessible to researchers connected to the project, and it was not possible to download the final trial data set.

The data will be available in 5 years from publication of the results.

To request access, proposals should be directed to the corresponding author. Data requestors will need to sign a data access agreement to gain access to the data.

The participants, the local coordinators and the volunteer peers cannot be blinded to the group allocation. The REDCap randomization tool will be used to facilitate randomization. To ensure concealment, the randomization schedule is stored away from the research team and the block sizes are not disclosed. The allocation is performed by a not-blinded research coordinator, who informs the participants allocated to the control group through a central telephone. Moreover, the research coordinator informs the local coordinators in each municipality about participants allocated to the intervention group through submitting the record id via secure email. The local coordinators will be able to identify the participants through their access to REDCap. The researchers will be blinded to group allocation during the process of data analysis.