Study spotlights link between socioeconomic position and death risk
A report that analysed the health status of nearly 10,000 civil servants in London, UK over a 25-year period has uncovered a strong association between risk of death and socioeconomic position. The findings are published in the Journal of the American Medical Association (JAMA). The British Whitehall Longitudinal Study began in 1985 and was carried out by researchers from the Centre for Research in Epidemiology and Population Health of the National Institute for Health and Medical Research (INSERM) in France. The civil servants participating in the study all lived in London and were aged between 35 and 55. Their socioeconomic status was classified from their employment grade (high, intermediate or low), and their health choices including smoking, drinking, exercise and diet were assessed four times over the timeframe of the study. The researchers examined the role played by health behaviours and choices in the association of socioeconomic position and poorer health or mortality. Much of the connection between economic status and risk of death was found to be due to health choices such as smoking, drinking alcohol, diet and exercise. Higher rates of unhealthy behaviour such as drinking and smoking in lower socioeconomic groups are usually seen to be key factors linking lower status to poorer health. However, the authors of the study pointed out: 'Major changes have occurred in population lifestyles. These include the decreasing prevalence of smoking and a remarkable increase in obesity since the 1990s. Given that changes in health behaviours may be socially patterned, previous studies with a single assessment of behaviours may have provided an inaccurate estimation of their contribution to the association between socioeconomic factors and mortality.' A total of 654 participants died during the 24-year follow-up period of the study. The researchers found that those with the lowest socioeconomic position had a 1.6 times higher risk of death from a variety of causes than those from the highest. Health behaviours assessed at baseline explained 42% of the association between socioeconomic position and death from a variety of causes. All the health behaviours taken together at baseline explained 29% of the gradient for cardiovascular mortality and 45% if they were entered as time-dependent covariates. 'The difference between the baseline only and repeated assessments of health behaviours was mostly due to an increased explanatory power of diet, physical activity, and alcohol consumption,' the authors wrote. 'The role of smoking, the strongest mediator in these analyses, did not change when using baseline or repeat assessments.' Health behaviours and choices explained a large proportion of the notable social inequalities in mortality in the study and they demonstrate the importance of taking into account changes over a period of time in health behaviour and choices when studying social inequality. 'Our findings may not necessarily have straightforward policy implications,' the authors commented. 'On the one hand, the findings imply that health policies and interventions focusing on individual health behaviours have the potential not only to increase the population's health but also to substantially reduce inequalities in health. 'On the other hand, if health behaviours are socially patterned and determined, for example, by financial factors, the capacity to respond to health education messages, or the environment in which [people] live, the same policies aimed at improving the population's health may contribute to an increase in social inequalities in health.'
Countries
France, United Kingdom