Background and Objective: There is increased interest in nature-based interventions (NBIs) to support mental health. These interventions are complex, operating across sectors, with a variety of activities, populations and environments. Previous research has highlighted poor elucidation of how and why context influences the outcomes observed in NBIs. In the United Kingdom, a rise in social prescribing, where people are supported into community/voluntary organisations, has expanded without concomitant evidence-based guidance to underpin intervention development. This presented an imperative to work with stakeholders to coproduce a nature-based intervention development resource.
Methods: A realist review was conducted to develop initial programme theory and inform a set of stakeholder interviews. Interviews explored identified mechanisms in the context of real-world experience. Subsequently, a workshop series engaging a wider pool of providers was carried out to refine guidance documentation.
Results: The realist review [n=1,343 results identified through database searches (n=5), plus reference scanning of key topic reviews, and grey literature review] identified 10 key mechanisms through which health and well-being benefits are likely to accrue through NBIs (Being outside, Making a difference, Being in a group, Physical activity, Personal achievement, Having fun, Personal growth, Creativity, Caring, Relationship to Nature). Interviews (n=13) helped to define pathways linking these mechanisms to 10 specific intervention activities and four types of outcomes. Preliminary guidance based on this logic model was developed. In workshops (n=4) (44 participants), theoretical exercises allowed providers to consider implementation of the guidance for their particular context and requirements; the results were used to refine the guidance. Conclusion: Coproduction allowed us to integrate the best available evidence with contemporary experience, to produce an evidence-based handbook which has validity for providers and is based on robust programme theory. Relevance and Importance to Patients: The handbook has more than 2,100 downloads, from 60 countries. It has been accessed by activity providers, health professionals, professional institutes, government departments and local authorities. Ongoing commissioned work, testing the feasibility of nature-based activities reached through social prescribing, builds on our programme theory. The aim is to provide patients with access to interventions that are appropriate, effective and safe.