Peer support interventions seeking to improve physical health and lifestyle behaviours among people with serious mental illness: A systematic review.

People with serious mental illness (SMI) experience a premature mortality gap of between 10 and 20 years. Interest is growing in the potential for peer support interventions (PSI) to improve the physical health of people with SMI. We conducted a systematic review investigating if PSI can improve the physical health, lifestyle factors, and physical health appointment attendance among people with SMI. A systematic search of major electronic databases was conducted from inception until February 2016 for any article investigating PSI seeking to improve physical health, lifestyle, or physical health appointment attendance. From 1347 initial hits, seven articles were eligible, including three pilot randomized, control trials (interventions: n = 85, controls: n = 81), and four pretest and post-test studies (n = 54). There was considerable heterogeneity in the type of PSI, and the role of the peer support workers (PSW) varied considerably. Three studies found that PSI resulted in insignificant reductions in weight. Evidence from three studies considering the impact of PSI on lifestyle changes was equivocal, with only one study demonstrating that PSI improved self-report physical activity and diet. Evidence regarding physical health appointment attendance was also unclear across four studies. In conclusion, there is inconsistent evidence to support the use of PSW to improve the physical health and promote lifestyle change among people with SMI. The small sample sizes, heterogeneity of interventions, outcome measures, and lack of clarity about the unique contribution of PSW means no definitive conclusions can be made about the benefits of PSW and physical health in SMI.