Background: People with chronic conditions experience functional impairment, lower quality of life, and greater economic hardship and poverty. Social isolation and loneliness are common for people with chronic conditions, with multiple co-occurring chronic conditions predicting an increased risk of loneliness. Peer support is a socially driven intervention involving people with lived experience of a condition helping others to manage the same condition, potentially offering a sense of connectedness and purpose, and experiential knowledge to manage disease. However, it is unclear what outcomes are important to patients across the spectrum of chronic conditions, what works and for whom. The aims of this review were to (1) collate peer support intervention components, (2) collate the outcome domains used to evaluate peer support, (3) synthesise evidence of effectiveness, and (4) identify the mechanisms of effect, for people with chronic conditions.

Methods: A systematic review of reviews was conducted. Reviews were included if they reported on formal peer support between adults or children with one or more chronic condition. Data were analysed using narrative synthesis.

Results: The search identified 6222 unique publications. Thirty-one publications were eligible for inclusion. Components of peer support were organised into nine categories: social support, psychological support, practical support, empowerment, condition monitoring and treatment adherence, informational support, behavioural change, encouragement and motivation, and physical training. Fifty-five outcome domains were identified. Quality of life, and self-efficacy were the most measured outcome domains identified. Most reviews reported positive but non-significant effects.

Conclusions: The effectiveness of peer support is unclear and there are inconsistencies in how peers are defined, a lack of clarity in research design and intervention reporting, and widely variable outcome measurement. This review presents a range of components of peer support interventions that may be of interest to clinicians developing new support programmes. However, it is unclear precisely what components to use and with whom. Therefore, implementation of support in different clinical settings may benefit from participatory action research so that services may reflect local need.