Background: A growing number of studies suggest that social isolation and loneliness are associated with premature mortality and are more prevalent among people with mental illness than in the general population, outlining many potential paths to disease still to be elucidated. The purpose of this meta-analysis is to examine the relationship between loneliness, social isolation, and established cardiovascular/metabolic risk factors and disorders, especially in severe mental illness, and to account for potential heterogeneity in the literature.
Methods/design: Studies that report measures of loneliness and/or social isolation along with cardiovascular/metabolic risk factors will be identified. PubMed, EMBASE (through Ovid SP), Scopus, and PsycINFO (through Ovid SP) will be searched, along with citation lists of retrieved articles and the Cochrane Database of Systematic Reviews. Grey literature will be searched using Google Scholar. Data will be extracted from eligible studies for a random effects meta-analysis. For each study, a summary effect size, heterogeneity, risk of bias, publication bias, and the effect of categorical and continuous moderator variables will be determined.
Discussion: This proposed systematic review and meta-analysis will identify and synthesise evidence to determine if there is an association between loneliness, social isolation, and cardiovascular/metabolic risk factors, with a special focus on severe mental illnesses. The results will help determine links and promising avenues of further research.
Systematic review registration: PROSPERO CRD42018111911.
Keywords: Cardiovascular risk; Loneliness; Mental illness; Meta-analysis; Metabolic syndrome; Social isolation.