Concordance of health states in couples: Analysis of self-reported, nurse administered and blood-based biomarker data in Understanding Society

There is limited evidence on the association of health status and comorbidities of marital/cohabitated partners despite the consequences for public policy on disability. Any tendency for disease or disability to be concentrated within couples will affect the social cost of disease. A second reason for interest in comorbidity within couples is that it may give useful insights regarding the causal processes generating health outcomes later in life. We develop a simple theoretical model that shows that the variation of the intra-couple health correlation with elapsed marriage/cohabitation duration is informative about the relative importance of homogamy (a tendency for people to choose partners similar to themselves) and causal concordance (increasing concordance of health states caused by lifestyle influences shared within the marriage). Using longitudinal data, we find important differences between the results for different health indicators, with strongest homogamy correlations observed for obesity (adiposity), associated biomarkers like blood pressure, heart rate, blood sugar and cholesterol, and also self-assessed general health. We find this correlation between partners’ health is unaffected by elapsed marriage/cohabitation duration, and we show theoretically that this implies – perhaps counterintuitively – that shared lifestyle factors and homogamous partner selection make roughly equal contributions to the concordance we observe in most of the health measures we examine. Keywords: Biomarkers; Health; Homogamy; Spousal concordance; Understanding Society