June 18, 2018

expert reaction to study looking at marital status and risk of heart disease, stroke and death

A new systematic review and meta-analysis, published in Heart, examines the association between marital status and risk of cardiovascular disease.

Prof Kevin McConway, Emeritus Professor of Applied Statistics, The Open University, said:

“This is far from being the first study that has found lower risk of serious diseases in married people compared to other groups.  In putting together data from several previous studies, it’s certainly very large, and competently performed and interesting, though most of the comparisons that are reported are based on relatively small proportions of the 2 million that were involved in total.

“However, one has to be a bit cautious about what the study is telling us.  The studies that were pooled to produce these results were all observational.  So they can’t rule out the possibility that the observed differences between married and unmarried people had nothing directly to do with their marital status.  Perhaps there are other factors that affect one’s chance of being, or staying, married and also, independently, affect the chances of heart diseases and stroke.  The individual studies that were combined to produce these new findings would all have made statistical adjustments to allow for some potential factors like this.  But as the researchers make clear, they did not all do this in the same way, and not all potential factors would have been allowed for, because of lack of the necessary data if nothing else.

“Even if the differences really are a consequence of marital status in some way, this new study cannot throw much light on how that could work.  The researchers do suggest several possible mechanisms – for example, support from a spouse in several different ways, negative effects from the loss of a spouse, lower chance of marriage to begin with if one’s health is already poor.  But this new study has no new way of investigating the evidence for any of these.  It does provide further impetus for investigating what might be behind differences in disease risk according to marital status, but that’s not going to be easy.  For instance, as the researchers point out, there was no information on people living together without being married, and the great majority of participants in the studies that were considered come from countries where cohabitation without formal marriage is relatively common, and where same-gender cohabitation or marriage relationships may well have importance but have not generally provided data to this study.  Maybe studies that concentrate on the potential mechanisms, some of which might well work in exactly the same way in cohabitation and in same-gender relationships as in heterosexual marriages, might throw more light on what’s going on.

“A minor point is that the press release says that the research drew on studies published between 1963 and 2015 – in fact they were all published after 2000 (and indeed, because of social change, studies older than that many well have shown different patterns).  A small amount of the data on which the original studies were based does date back to 1963, though most is more recent.”

* ‘Marital status and risk of cardiovascular diseases: a systematic review and meta-analysis’ by Chun Wai Wong et al. published in Heart on Monday 18 June 2018. 

Declared interests

Prof Kevin McConway: “Kevin McConway is a member of the Science Media Centre’s Advisory Committee.”