Marital status may influence risk of cardiovascular outcomes after myocardial infarction

Chun Wai Wong (Cardiovascular Research Group, Keele University, Stroke-on-Trent, UK) and others report in Heart that, following a myocardial infarction, single people have a significantly increased risk of all-cause mortality compared with their married counterparts. In this commentary, Wong outlines the key findings of the study and their implications.

Our meta-analysis on marital status and cardiovascular diseases included 34 studies with more than two million people aged between 42 and 77 from Europe, Scandinavia, North America, the Middle East, and Asia. Pooled analysis of the data revealed that—compared with married individuals—those who were single (defined as never married, divorced or widowed) were at heightened risk of developing cardiovascular diseases (42%) and coronary heart disease (16%). Additionally, not being married was also associated with a heightened risk of dying from both coronary heart disease (42%) and stroke (55%). When the data were broken down further, the analysis showed that divorce was associated with a 35% higher risk of developing coronary artery disease for both men and women and that widows and widowers were 16% more likely to have a stroke.

While there was no difference in the risk of death following a stroke between the married and the unmarried, this was not the case after a myocardial infarction; the risk of which was significantly higher (42%) among those who had never married. Additionally, contrary to the previous studies that suggested men benefit more from being married, our analysis found no significant gender difference in the cardiovascular disease risks according to marital status.

Theories to account for the protective effect of marriage include earlier recognition of, and response to, health symptoms; better adherence to medication and rehabilitation; healthier lifestyle; and greater emotional support and financial security.

Myocardial infarctions account for nearly 200,000 hospital visits each year in the UK and represent the most common cause of death from coronary heart disease.² Thus, identifying at-risk patients and optimising post intervention care are of paramount importance. Possible ways for physicians to better support single patients after a myocardial infarction revolve around reinforcing the current good practice. For example, more detailed explanation of the role of medications to promote adherence; patient education to understand disease and recognise symptoms of deterioration or recurrence; optimise cardiovascular risk profiles by referral to smoking cessation service, exercise programme or dietician review if applicable; and shorter time to follow ups.

Loneliness/social isolation vs. marital status on cardiovascular diseases

There is readily available evidence documenting the association between loneliness or social isolation with greater morbidity and mortality.^3,4 A meta-analysis published in 2016, with pooled results from 15 studies, reported an increased risk of coronary heart disease (29%) and stroke (32%) among individuals with poor social relationships.⁵ As marital status is a form of personal relationship, there are similarities observed in our study.

However, it is important to understand the different nature of our study on marital status and the other studies on loneliness or social isolation. In previous studies, the definition of loneliness was often subjective and determined by the questionnaires that elicited participants’ inner feelings.⁵ Furthermore, social isolation was assessed using screening tools such as the Berkman–Syme Social Network Index, Lubben Social Network Scale, Duke Social Support Index and other tools that were based on the availability and frequency of contacts.^5–8

Briefly, of the three screening tools mentioned above, only Berkman–Syme Social Network Index included marital status as independent criteria.⁶ Whereas for the other two screening tools, marital status carries an indirect influence. As their questionnaires predominantly focused on the frequency and quality of contacts with relatives, an individual with a spouse would be expected to score higher and thus less likely to be socially isolated.

However, as highlighted by Vujcic et al, living alone does not always equate to low degree of social support and living with someone does not assure a high level of social support.⁹ Some people are able to maintain a large social network while living alone, whereas others receive little social support from a spouse, friend or relative with whom they live.⁹

Nonetheless, cohabitation represents a potential confounder in this study and was not thoroughly considered in every studies we analysed. Fortunately, few studies provided some insight on this. In Kilpi et al, when compared to unmarried cohabitating individuals, married men have a significant lower risk of developing myocardial infarction.¹⁰ Similarly Quinones et al found that, when compared to unmarried cohabitating individuals, married individuals of both sexes have a considerably lower risk of cardiovascular deaths.¹¹ These findings suggest that there might be extra elements in a marriage that confer better health in addition to the social support received from cohabitation.

The senior author of our study,  Mamas A Mamas (Cardiovascular Research Group, Keele University, Stroke-on-Trent, UK), mentioned in a recent interview that while social relationships are important, the question is more how close the relationship needs to be to have an impact on health benefits.¹²

References

1. Wong et al. Heart 2018. Epub.
2. CVD statistics—BHF UK factsheet. https://bit.ly/2O7jqBc [date accessed 23 July 2018]
3. Holt-Lunstad et al. Perspect Psychol Sci 2015; 10(2): 227–37.
4. Holt-Lunstad et al. PLoS Med 2010; 7(7): e1000316..
5. Valtorta et al. Heart 2016; 102(13): 1009–16.
6. Berkman et al. Health and ways of living. New York: Oxford University Press, 1983.
7. Lubben J. Fam Community Health 1988; 11: 42–52.
8. George et al. Br J Psychiatry 1989; 154(4): 478–85.
9. Vujcic et al. Ir J Med Sci 2015; 184: 153–58.
10. Kilpi et al. Soc Sci Med 2015; 133: 93–100.
11. Quinones et al. BMC Public Health 2014; 14: 98.
12. The Naked Scientist. https://bit.ly/2JManlT [date accessed 23 July 2018]

Chun Wai Wong is at Cardiovascular Research Group, Keele University, Stroke-on-Trent, UK.