'Known to be unhealthy': Exploring how social epidemiological research constructs the category of low socioeconomic status.

We examine how the category of low socioeconomic status (LSES) was constructed in European social epidemiological research and policy advice from 1977 to 2019. We analysed 22 empirical social epidemiological research publications on LSES and health, as well as six scientific advisory reports that offered government officials an overview of scientific evidence on health inequalities. We show the construction and reification of LSES as a problematic group in dominant thought, which consists of the following components: 1) the proliferation of SES concepts, indicators and groups labelled LSES; 2) generalisation through which LSES is constructed as a single population; 3) problematisation through which LSES is constructed as an inherently unhealthy population; and 4) individualisation by which a LSES personality is presented as an explanation of health differences. We also show how this knowledge is extrapolated into the policy domain in the form of scientific advisory reports. These findings provide evidence of the construction of LSES as an inherently unhealthy population through hyperproliferation and references to the objectivity of scientific research. With respect to the LSES category, the dynamics of research and policy resemble those regarding categories of ethnicity and gender. We conclude that if the construction of LSES remains unquestioned, social epidemiology might continue to (re)produce what it examines: LSES populations 'known to be unhealthy'.