According to a study by Silvia Stringhini and colleagues from INSERM, (U1018 Centre for Research in Epidemiology and Population Health) and University College London, (Department of Epidemiology and Public Health), published in this week's PLoS Medicine, although socioeconomic status and health behaviors are strong predictors of mortality, there are major differences in the social patterning of unhealthy behaviors in different countries.
The authors investigated whether health behaviours are equally important mediators of the association between socio-economic status and health in different cultural settings. They compared recent findings of the British Whitehall II study with those of another European cohort, the French GAZEL study. Both large cohort studies have comparable designs and have a similar age range and follow-up period. The Whitehall II study started in 1985, with the aim of examining the socioeconomic gradient in health among 10308 London-based civil servants (6895 men and 3413 women) aged 35-55. The GAZEL study started in 1989 among employees of the French national gas and electricity company totalling 20625 employees (15011 men and 5614 women), aged 35-50.
The authors found that the socioeconomic gradient in smoking and unhealthy diet was greater in Whitehall II than in GAZEL. Socioeconomic differences in mortality were similar in the two cohorts, a hazard ratio of 1.62 in Whitehall II and 1.94 in GAZEL for lowest versus highest occupational position. Health behaviours weakened the association between socio-economic status and mortality substantially in Whitehall II (by 75%) but only by 19% in GAZEL. The supplementary analysis the researchers conducted using education and income as socio-economic markers gave similar results.
These findings are important as they show that health behaviours are only likely to be major contributors towards socioeconomic differences in health in settings with a marked social characterisation of those behaviours. The authors conclude that in order to identify the common and unique determinants of social inequalities in health in different populations, "there needs to be further comparative research on the relative importance of different pathways linking socioeconomic status to health."
Funding: The Whitehall II study was supported by grants from the British Medical Research Council (grant number: G0902037); the British Heart Foundation (grant number: RG/07/008/23674); the British Health and Safety Executive; the British Department of Health; the National Heart, Lung, and Blood Institute, NIH (grant number: R01HL036310); the National Institute on Aging, NIH (grant numbers: R01AG013196 and R01AG034454). The GAZEL Cohort Study was funded by EDF-GDF and INSERM, and received grants from the Cohortes Sante TGIR Program, Agence nationale de la recherche (ANR) and Agence francaise de securite sanitaire de l'environnement et du travail (AFSSET). This work was supported by a ''European Young Investigator Award'' from the European Science Foundation to AS-M, a grant from the British Heart Foundation to MS, grants from the BUPA Foundation, UK; EU OSH ERA research program and the Academy of Finland to MK. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Citation: Stringhini S, Dugravot A, Shipley M, Goldberg M, Zins M, et al. (2011) Health Behaviours, Socioeconomic Status, and Mortality: Further Analyses of the British Whitehall II and the French GAZEL Prospective Cohorts. PLoS Med 8(2): e1000419. doi:10.1371/journal.pmed.1000419
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