March 26, 2018 | News | News

The poor are less healthy. But why?

It is well known that there is a connection between socioeconomic status and health. But to this day, we do not know whether being poor makes people ill or whether poor health leads to poverty. MPIDR researcher Rasmus Hoffmann has now investigated this relation and found that there is not one answer that applies to all stages of life.

(this news is based on the scientific article Pathways between socioeconomic status and health: Does health selection or social causation dominate in Europe?, that has been the instantly published in the journal Advances in Life Course Research on February 24, 2018, the final version of this article has been published on March 24, 2018)

The poor are less healthy and die earlier. It has long been known that there is a connection between income and education on the one hand and health and life expectancy on the other. It is obvious that this difference has something to do with health and health behavior. Still unknown, however, is the relationship between health and the so-called socioeconomic status, a common measure in the social sciences consisting of an array of components, such as educational attainment, occupation and income, place of residence and ownership.

"The big question is whether health affects socioeconomic status or whether it's just the other way round, namely that a low socioeconomic status has a negative impact on health," says MPIDR researcher Rasmus Hoffmann. He is the lead author of a study published online in the journal Advances in Life Course Research. In the paper, he addresses this very question.

Researchers call it "social causation" when socioeconomic status has an impact on health. One example is a lack in understanding healthy lifestyle due to a low level of education. "Health selection" is called the assumption that health has an impact on socioeconomic status. For instance, frequent illness in childhood may have led to longer periods missed at school and thus to a lower education level. This again may later affect income levels.

"We wanted to identify the prdominant causal direction. So we examined the direction in which the two factors influence each other in order to understand what the cause is and what the effect is," explains Hoffmann.

The data source used by the researchers is the Survey of Health Aging and Retirement in Europe (SHARE). For this survey, people aged 50 and over are questioned about health and social issues across the entire life course. The researchers used data from 10 European countries from this data set, and this provided them with a data set of over 20,000 interviews.

"The difficulty with this kind of research is that both socioeconomic status and health not only change throughout the life course, but also affect each other," explains Hoffmann.

The researchers thus divided their data into three stages of the life course to examine the predominance of causal direction at two stages of transition: from childhood to adulthood and from working ages to old ages. “This is a unique feature of this study,” says Hoffmann. "Previous studies looked at just one phase of the life course or the life course as a whole. Our study examines for the first time ever whether and how the relative importance of 'social causation' and 'health selection' change over the course of a lifetime."

The calculations of the researchers confirmed that socioeconomic status and health are directly linked and mutually influential: Low socioeconomic status for the most part is associated with poorer health, whereas people of higher socioeconomic status on average are healthier. The researchers could also confirm that socioeconomic status is consolidated over the life course. Most importantly, however, they noted that during the transition from childhood to working age the two causal directions – social causation (socioeconomic status influences health) and health selection (health influences socioeconomic status) – were equally important. Interestingly, this situation did not last, but changed when looking at the transition from working ages to old ages. Here the influence of socioeconomic status on health clearly prevails. Possible explanations are that health problems arising during the aging process depend in particular on social factors and that health can only have a small impact on the socio-economic status when people receive a pension, Hoffmann said.

The results of the researchers are relevant for societies because illness causes high costs to the healthcare system. Hoffmann: "Only when we know how health and wealth interact in the life course, can the right policy action be taken in every age group to reduce health inequalities."