The Relationship between Income and Health: Evidence from Nationwide Health Exams in Korea

We examine how physical health, health behaviors, and mortality vary with income for prime-age adults. To do so, we leverage population-wide, individual-level cardiovascular health exams linked to income tax records and subsequent mortality for a representative sample of about 350,000 Koreans aged 47--57. For both men and women, there is a negative disease-income gradient for high blood pressure, high blood glucose, and high body mass index, but not for high cholesterol. Disease-income gradients are steeper for women than men, and tend to be concentrated in the top half of the income distribution; similar patterns hold for health behavior-income gradients. Subsequent mortality-income gradients are also concentrated in the top half of the income distribution, but are steeper for men than women. Although physical health and behavior measures are highly predictive of subsequent mortality, differences in these measures by income explain very little of the income-mortality gradient, even for cardiovascular mortality. Our findings suggest that something other than differences in disease burden at prime age drives most of the income-mortality gradient at older ages.