Social isolation and risk of fatal cardiovascular events
Authors: Janine Gronewold, Dirk M Hermann
Journal: The Lancet Public Health (2021)

Since the start of the COVID-19 pandemic in March, 2020, in-person contact with family members, friends, and colleagues has been heavily restricted. These mitigation measures can worsen pre-existing social isolation.1Cudjoe TKM Kotwal AA "Social Distancing" amid a crisis in social isolation and loneliness.J Am Geriatr Soc. 2020; 68: e27-e29Crossref PubMed Scopus (45) Google Scholar In this phase of widespread insecurity, evidence on the prevalence and cardiovascular consequences of social isolation represents an important guideline for estimating the health consequences of COVID-19. Despite continuous therapeutic progress, coronary heart disease and stroke remain the leading causes of death globally.2WHOThe top 10 causes of death.https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-deathDate: Dec 9, 2020Date accessed: December 14, 2020Google Scholar Social isolation has previously been associated with increased risk of coronary heart disease and stroke events,3Gronewold J Engels M van de Velde S et al.Effects of life events and social isolation on stroke and coronary heart disease.Stroke. 2021; (published online Jan 15.)https://doi.org/10.1161/STROKEAHA.120.032070Crossref PubMed Scopus (5) Google Scholar, 4Valtorta NK Kanaan M Gilbody S Ronzi S Hanratty B Loneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and meta-analysis of longitudinal observational studies.Heart. 2016; 102: 1009-1016Crossref PubMed Scopus (588) Google Scholar however, the impact of isolation on coronary heart disease and stroke survival remains unclear. In The Lancet Public Health, Robert Smith and colleagues5Smith RW Barnes I Green J Reeves GK Beral V Floud S Social isolation and risk of heart disease and stroke: analysis of two large UK prospective studies.Lancet Public Health. 2020; (published online March 1.)https://doi.org/10.1016/S2468-2667(20)30291-7Google Scholar have attempted to address this knowledge gap through a combined analysis of data from 481 946 participants included in the Million Women Study and 456 612 participants from UK Biobank Study without previous coronary heart disease or stroke. In this large dataset, 42 402 first coronary heart disease events (1834 fatal events) and 19 999 first stroke events (529 fatal events) occurred during a mean follow-up of 7 years (SD 2). In the Million Women Study and UK Biobank social isolation was assessed quantitatively via a summary index of the number of people living together in a household and the frequency of contact with family, friends, and groups. Based on this index, participants were categorised into least isolated (379 031 [40%] of 938 558 participants), moderately isolated (429 541 [46%]), and most isolated (129 986 [14%]) groups, with the least isolated group defined as the reference group. Consistent with previous literature,3Gronewold J Engels M van de Velde S et al.Effects of life events and social isolation on stroke and coronary heart disease.Stroke. 2021; (published online Jan 15.)https://doi.org/10.1161/STROKEAHA.120.032070Crossref PubMed Scopus (5) Google Scholar, 4Valtorta NK Kanaan M Gilbody S Ronzi S Hanratty B Loneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and meta-analysis of longitudinal observational studies.Heart. 2016; 102: 1009-1016Crossref PubMed Scopus (588) Google Scholar, 6Gronewold J Kropp R Lehmann N et al.Association of social relationships with incident cardiovascular events and all-cause mortality.Heart. 2020; 106: 1317-1323Crossref PubMed Scopus (6) Google Scholar individuals in the most isolated group reported more pronounced health-risk behaviours, such as smoking and physical inactivity, and were more likely to be obese, in poor health (self-rated), and live in more deprived areas (based on the Townsend Deprivation index) than the least isolated group. Multivariable Cox regression analyses controlling for health behaviours and established cardiovascular risk factors (age, sex, region of recruitment, deprivation, smoking, alcohol intake, physical activity, body-mass index, and self-rated health) identified no significant overall association between social isolation (most isolated vs least isolated) and non-fatal coronary heart disease (combined risk ratio [RR] for both studies 1·01 [95% CI 0·98–1·04]) and non-fatal stroke (1·13 [1·08–1·18]). In contrast, there were clear associations with fatal coronary heart disease (1·86 [1·63–2·12]) and fatal stroke (1·91 [1·48–2·46]). When different types of social isolation were analysed separately, associations were stronger for participants living alone than not alone (RR 1·60 [95% CI 1·46–1·75] for fatal coronary heart disease and stroke combined) and for participants with few versus more social contacts (1·27 [1·16–1·38]). Results did not differ significantly between the two studies, or by self-rated health, sex, or cardiovascular risk profile. Considering that fatal events were defined as death due to first coronary heart disease or stroke event without previous hospital admission, the association observed between social isolation and fatal events, but not with non-fatal events, could imply that this association is mediated by the absence of another person who can assist in seeking health-care following a cardiovascular event. This interpretation is supported by the stronger effect of living alone than having few social contacts. Considering the large sample size of this combined analysis, this observation provides strong rationale for future intervention studies, in which the potential benefits of personal emergency alarms and internet-based surveillance in reducing fatal coronary heart disease and stroke events are assessed. To date, a variety of methods for evaluating social relationships have been used in the literature. One limitation of the study by Smith and colleagues5Smith RW Barnes I Green J Reeves GK Beral V Floud S Social isolation and risk of heart disease and stroke: analysis of two large UK prospective studies.Lancet Public Health. 2020; (published online March 1.)https://doi.org/10.1016/S2468-2667(20)30291-7Google Scholar is the authors were only able to evaluate the consequences of having few contacts, but not of an excess of contacts, which can also be stressful. Furthermore, the quality of social contacts6Gronewold J Kropp R Lehmann N et al.Association of social relationships with incident cardiovascular events and all-cause mortality.Heart. 2020; 106: 1317-1323Crossref PubMed Scopus (6) Google Scholar was not assessed. The social isolation index used in the Million Women Study included questions about email, phone, and in person contacts, whereas the UK Biobank study only included questions on in-person contact. To achieve better comparability, future studies should seek consensus on how different aspects of social relationships can best be assessed. In-person contacts and virtual contacts should be differentiated in future studies, considering that virtual contacts such as video conferences have predominated social interactions during the COVID-19 pandemic. In the context of psychiatric disorders, it has already been shown that in-person social contacts protect against mood disorders, but this has not been observed for online contacts.7Teo AR Chan BK Saha S Nicolaidis C Frequency of social contact in-person vs. on Facebook: an examination of associations with psychiatric symptoms in military veterans.J Affect Disord. 2019; 243: 375-380Crossref PubMed Scopus (9) Google Scholar For the assessment of health consequences, the differentiation between contacts with family versus friends and other groups also requires attention in future studies. Social contacts have largely been restricted to household members during COVID-19 lockdowns. For the outcome of all-cause mortality, it has been shown that support from family members was more beneficial than support from friends.8Shor E Roelfs DJ Yogev T The strength of family ties: a meta-analysis and meta-regression of self-reported social support and mortality.Soc Networks. 2013; 35: 626-638Crossref Scopus (108) Google Scholar Smith and colleagues suggested that the absence of another person who could assist with health-care seeking during acute events might explain the association between social isolation and fatal cardiovascular disease.5Smith RW Barnes I Green J Reeves GK Beral V Floud S Social isolation and risk of heart disease and stroke: analysis of two large UK prospective studies.Lancet Public Health. 2020; (published online March 1.)https://doi.org/10.1016/S2468-2667(20)30291-7Google Scholar Such findings contradict the results of the REGARDS cohort study, which showed that having contact with family or friends in the past months—but not having anyone to care for you if you become ill or disabled—was significantly associated with incident fatal coronary heart disease.9Safford MM Reshetnyak E Sterling MR et al.Number of social determinants of health and fatal and nonfatal incident coronary heart disease in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study.Circulation. 2020; (published online Dec 3.)https://doi.org/10.1161/CIRCULATIONAHA.120.048026Google Scholar Smith and colleagues observed little effect modification of social isolation-related health consequences by sex, however, it has previously been shown that men who live alone have a significantly higher long-term mortality risk following acute myocardial infarction than women.10Schmaltz HN Southern D Ghali WA et al.Living alone, patient sex and mortality after acute myocardial infarction.J Gen Intern Med. 2007; 22: 572-578Crossref PubMed Scopus (70) Google Scholar In addition to sex, social determinants, character traits, previous experiences, and genetic factors can modify the cardiovascular impact of social isolation.3Gronewold J Engels M van de Velde S et al.Effects of life events and social isolation on stroke and coronary heart disease.Stroke. 2021; (published online Jan 15.)https://doi.org/10.1161/STROKEAHA.120.032070Crossref PubMed Scopus (5) Google Scholar The COVID-19 pandemic has highlighted the need to develop of a more comprehensive view of the health consequences of social isolation. The analysis by Smith and colleagues5Smith RW Barnes I Green J Reeves GK Beral V Floud S Social isolation and risk of heart disease and stroke: analysis of two large UK prospective studies.Lancet Public Health. 2020; (published online March 1.)https://doi.org/10.1016/S2468-2667(20)30291-7Google Scholar provides an important contribution to this task. With a better understanding of social isolation, and a focus on internet-based surveillance and telemedicine interventions, prevention of the devastating, and specifically fatal, health effects of such isolation might be possible. We declare no competing interests. Social isolation and risk of heart disease and stroke: analysis of two large UK prospective studiesSocial isolation seems to have little direct effect on the risk of developing a first coronary heart disease or stroke. By contrast, social isolation substantially increases the risk that the first such event is fatal before reaching hospital, particularly among people who live alone, perhaps because of the absence of immediate help in responding to an acute heart attack or stroke. Full-Text PDF Open Access