In the study, researchers compared socioeconomic status against six of the main risk factors defined by the World Health Organisation in its Global Action Plan for the Prevention and Control of Non-Communicable Diseases. The plan aims to reduce non-communicable diseases by 25% by 2025, but omits socioeconomic status as a risk factor for these diseases.
– Education, income, and work are known to affect health, but few studies have examined how important these socioeconomic factors actually are. Our study aims to compare the effect of socioeconomic status with the major risk factors targeted in global health strategies, says Professor Mika Kivimaki, University of Helsinki and University College London, the senior author of the study.
The meta-analysis included data from 48 studies comprising more than 1.7 million people from Europe, USA and Australia. The study used a person’s job title to estimate their socioeconomic status and looked at whether they died early.
In the study, 41% of men and 27% of women had low socioeconomic status. Low socioeconomic status was associated with reduced life expectancy of 2.1 years, similar to being physically inactive (2.4 years). The greatest reductions were for smoking and diabetes (4.8 and 3.9 years, respectively). Comparatively, high blood pressure, obesity and high alcohol consumption were associated with smaller reductions in life expectancy (1.6, 0.7 and 0.5 years, respectively) than low socioeconomic status.
Limitations of the study include that the researchers only used occupational position as the indicator of socioeconomic status. While it is a commonly used measure, it can risk over simplifying the complexity of socioeconomic status. Although the study analysed and controlled for low socioeconomic status as an independent risk factor, the authors say it is difficult to separate the effects of socioeconomic status from other risk factors, highlighting the importance of targeting it alongside conventional risk factors for health included in global health targets.
Professor Mika Kivimäki, University of Helsinki
Reference: Silvia Stringhini, Mika Kivimäki & al, for the LIFEPATH consortium: Socioeconomic status and the 25 × 25 risk factors as determinants of premature mortality: a multicohort study and meta-analysis of 1·7 million men and women. Lancet 31st January 2017.