This systematic overview highlights that there is consistent evidence linking social isolation and loneliness to worse cardiovascular and mental health outcomes. The role of social isolation and loneliness in other conditions and their socio-economic consequences is less clear. More research is needed on associations with cancer, health behaviours, and the impact across the life course and wider socio-economic consequences. Policy makers and health and local government commissioners should consider social isolation and loneliness as important upstream factors impacting on morbidity and mortality due to their effects on cardiovascular and mental health. Prevention strategies should therefore be developed across the public and voluntary sectors, using an asset-based approach.

BackgroundThe influence of social relationships on morbidity is widely accepted, but the size of the risk to cardiovascular health is unclear.ObjectiveWe undertook a systematic review and meta-analysis to investigate the association between loneliness or social isolation and incident coronary heart disease (CHD) and stroke.MethodsSixteen electronic databases were systematically searched for longitudinal studies set in high-income countries and published up until May 2015. Two independent reviewers screened studies for inclusion and extracted data. We assessed quality using a component approach and pooled data for analysis using random effects models.ResultsOf the 35 925 records retrieved, 23 papers met inclusion criteria for the narrative review. They reported data from 16 longitudinal datasets, for a total of 4628 CHD and 3002 stroke events recorded over follow-up periods ranging from 3 to 21 years. Reports of 11 CHD studies and 8 stroke studies provided data suitable for meta-analysis. Poor social relationships were associated with a 29% increase in risk of incident CHD (pooled relative risk: 1.29, 95% CI 1.04 to 1.59) and a 32% increase in risk of stroke (pooled relative risk: 1.32, 95% CI 1.04 to 1.68). Subgroup analyses did not identify any differences by gender.ConclusionsOur findings suggest that deficiencies in social relationships are associated with an increased risk of developing CHD and stroke. Future studies are needed to investigate whether interventions targeting loneliness and social isolation can help to prevent two of the leading causes of death and disability in high-income countries.Study registration numberCRD42014010225.

ObjectivesWe present a novel way of classifying and comparing measures of social relationships to help readers interpret the growing literature on loneliness and social isolation and to provide researchers with a starting point to guide their choice of measuring tool.MethodsMeasures of social relationships used in epidemiological studies were identified from two systematic reviews—one review on the association between social relationships and health and social care service use, and a second review on the association between social relationships and health. Questions from each measure were retrieved and tabulated to derive a classification of social relationship measures.ResultsWe present a classification of measures according to two dimensions: (1) whether instruments cover structural or functional aspects of social relationships and (2) the degree of subjectivity asked of respondents. We explain how this classification can be used to clarify the remit of the many questionnaires used in the literature and to compare them.ConclusionsDifferent dimensions of social relationships are likely to have different implications for health. Our classification of social relationship measures transcends disciplinary and conceptual boundaries, allowing researchers to compare tools that developed from different theoretical perspectives. Careful choice of measures is essential to further our understanding of the links between social relationships and health, to identify people in need of help and to design appropriate prevention and intervention strategies.

Bible to modern critiques of the digital age, loneliness has been portrayed as part of the human condition. Recognition of the significant adverse consequences for health has come more recently, with much of the interest triggered by a rise in the death rate in Europe in 2003. Unusually high temperatures in the summer of that year were linked with the deaths of more than 40,000 mainly elderly people throughout mainland Europe. Proportionately fewer deaths were recorded among frail and sick older people living in institutions, compared with more able, but less well-supported people living in the community. These deaths stimulated much discussion and reflection on the treatment of elders in society. In France, and later the UK, nongovernmental organizations instigated campaigns to address loneliness and isolation among the aged. Such campaigns, along with research from different disciplines linking loneliness and isolation with adverse health outcomes and premature mortality, have focused attention on the problems. But despite acknowledgement of isolation in the UK National Service Framework for Older People in relation to falls and depression, 1 concern among care providers and commissioners has never matched the breadth and severity of the consequences of isolation and loneliness. In this article, we present an overview of current evidence and suggest that a renewed research agenda is required for a growing older population.