This study assessed the acceptability, appropriateness, feasibility and initial efficacy of the gPM+ intervention, delivered by non-specialists to adults with moderate levels of common mental health problems in an urban informal settlement in Kenya. The findings show that lay facilitators from a local grassroot organization can be trained to achieve the desired competency to effectively implement the intervention in the community under supervision. Overall, intervention uptake was excellent, with gPM+ considered appropriate, acceptable and therapeutic by participants and lay facilitators. The outcome evaluation, which was not powered, nonetheless demonstrated relevant improvements in symptoms of anxiety, depression, PTSD, functioning, social support, general wellbeing and self-identified problems across all the timepoints. The feasibility of assessments, procedures and intervention suggests that a fully powered gPM+ evaluation trial is achievable in this context.

To the best of our knowledge, this is the first formative study in Kenya to look at the appropriateness, acceptability, feasibility and potential efficacy of the gPM+. Previous PM+ studies in this setting have examined the acceptability, feasibility and effectiveness of the individual version of PM+ among young people at the coast of Kenya (Nyongesa et al. 2022) and women with a history of gender-based violence in urban Kenya (Bryant et al. 2017; Van’t Hof et al. 2018). Our findings add to the body of research evidence on PM+ in Kenya and further supports the implementation and dissemination of this low-intensity psychological intervention among adults facing adversities in urban informal settlements. Notably, group-based programs may be more cost-effective than individually implemented mental health interventions (Huntley et al. 2012), and when they can be successfully delivered by lay facilitators, this further enhances the likelihood that programs like gPM+ could be implemented in informal settlements in low-resource countries (Hamdani et al. 2020).

In LMICs, the use of trained and supervised lay counsellors for the implementation of mental health interventions has been preferred given the high treatment gap and severe shortage of mental health specialists (Chibanda et al. 2011; Van Ginneken et al. 2011). This study extends the growing evidence in support of task-shifting approaches in the delivery of evidence-based psychological interventions (Van Ginneken et al. 2011). The high acceptability and successful implementation of this feasibility study suggests that lay facilitators can effectively deliver gPM+ after training and continued supervision. Local religious and administrative leaders introduced the lay facilitators to the community as part of community engagement before participants’ recruitment began. This was ideal as they are trusted and respected in the communities, overcoming a likely barrier in accessing study participants. Additionally, our partnership with representatives of a grassroot organization as implementers of gPM+ likely ensured acceptability and an ability to relate well to their participants. There is evidence showing participants can have preference for delivery agents from within their localities over outside agents, as they are easily accessible and reduce the stigma attached to help seeking (Singla et al. 2014). Moreover, local selection is considered to increase the potential for future intervention scale-up. The lay facilitators had at least 12 years of education, and with some experience in community mental health promotion, enabling access to a large pool of potential people who can take up this role. Furthermore, locally selected facilitators could be more conscious of the local context, which is important in intervention implementation. The use of lay facilitators was also found to be acceptable in previous PM+ exploratory studies in Kenya (Nyongesa et al. 2022; Van’t Hof et al. 2018).

The supervision models utilized in this study are potentially scalable, with a few specialists in another location able to provide group supervision to several facilitators through virtual meetings. Moreover, the group format of supervision enabled lay facilitator support and supervision, which was found to be essential in managing difficult situations during field activities e.g. facilitators’ psychological wellbeing.

The high recruitment of respondents into the project supports the feasibility of enrolling adults in urban informal settlements into gPM+ intervention. We observed a 100% retention at the end of the intervention, and a good retention of 88% at 3-months follow-up, which is higher than that reported in previous formative studies (Nyongesa et al. 2022). It is important to note however, that the recruitment of male participants was met with hesitancy at first due to their belief that only those with severe mental illnesses needed support, their busy schedules and fear of sharing their issues with others, especially the opposite gender. Similar observations have been reported elsewhere and emphasize the importance of using de-stigmatizing local idioms and language during the planning and community engagement phase with different stakeholders (Kohrt and Hruschka 2010). As experienced by the facilitators in this project, sensitization meetings, worked to normalize experiencing adversity and distress, as well as to emphasize that gPM+ was for those experiencing common mental health problems. To enhance the recruitment of men, facilitators expanded their recruitment places to include workplaces, and areas mostly frequented by men. During the implementation of the programme, we held separate groups for men and women. The overall feasibility and acceptability of conducting the intervention amongst men indicates that it is possible to include both genders in a large trial in the Kenyan context, with some potential barriers in recruitment.

Exit interviews with participants revealed that all gPM+ strategies were contextually appropriate. This was corroborated by the qualitative interviews with the lay facilitators. When implemented, we observed a consistent trend towards a reduction in symptoms of common mental disorders across all timepoints, which was statistically significant relative to baseline assessments although the study was not powered to detect clinically significant differences on outcome measures. We also observed a similar pattern for the other psychosocial and functional outcomes, i.e. social support, functional impairment, general wellbeing and self-identified problems. These results are consistent with previous findings in Kenya (Dawson et al. 2016; Nyongesa et al. 2022; Van’t Hof et al. 2018) and other settings (Acarturk et al. 2022; Sangraula et al. 2020).

The results of this study suggest that the implemented gPM+ appears contextually appropriate in an urban informal settlement at the coast of Kenya. Additionally, the use of lay facilitators drawn from a local community-based organization is also feasible and acceptable. Additionally, it is feasible to recruit and retain participants in the gPM+ intervention, evidenced by the good response rate and retention rates, with some potential barriers in the recruitment of men. It is also feasible to implement five weekly sessions of about 2 hours each via face-to-face meetings. Initial feasibility data indicates that gPM+ has the potential to alleviate symptoms of common mental disorders and improve participants’ psychosocial and functional wellbeing. The findings from this study give preliminary evidence important in guiding the community implementation of gPM+ in this setting. There may be need to assess and ascertain to what extent lay facilitators can retain the gPM+ knowledge and skills for continued therapy in the community. A further qualitative evaluation of gPM+ with different stakeholders, e.g. local leaders, gPM+ participants and providers, county ministry of health officials, and healthcare providers, can provide additional insights into the possible barriers and facilitators of implementing gPM+ in this setting.