Area-level socioeconomic characteristics and incidence of metabolic syndrome: a prospective cohort study
1 Social Epidemiology and Evaluation Research Group, Sansom Institute for Health Research, and School of Population Health, University of South Australia, Adelaide 5001, Australia
2 Research Centre of the Douglas Mental Health University Institute, Verdun, Québec H4H 1R2, Canada
3 The Health Observatory, Discipline of Medicine, The University of Adelaide, Adelaide, South Australia 5005, Australia
4 Population Research and Outcome Studies, Discipline of Medicine, The University of Adelaide, Adelaide, South Australia 5005, Australia
5 Department of Medicine, The University of Melbourne, St Vincent’s Hospital, Melbourne, Victoria 3065, Australia
6 Social Epidemiology and Evaluation Research Group, Sansom Institute for Health Research, and School of Population Health, University of South Australia, P4-18F, Playford Building, City East Campus, Adelaide 5000, Australia
BMC Public Health 2013, 13:681 doi:10.1186/1471-2458-13-681Published: 25 July 2013
The evidence linking socioeconomic environments and metabolic syndrome (MetS) has primarily been based on cross-sectional studies. This study prospectively examined the relationships between area-level socioeconomic position (SEP) and the incidence of MetS.
A prospective cohort study design was employed involving 1,877 men and women aged 18+ living in metropolitan Adelaide, Australia, all free of MetS at baseline. Area-level SEP measures, derived from Census data, included proportion of residents completing a university education, and median household weekly income. MetS, defined according to International Diabetes Federation, was ascertained after an average of 3.6 years follow up. Associations between each area-level SEP measure and incident MetS were examined by Poisson regression Generalised Estimating Equations models. Interaction between area- and individual-level SEP variables was also tested.
A total of 156 men (18.7%) and 153 women (13.1%) developed MetS. Each percentage increase in the proportion of residents with a university education corresponded to a 2% lower risk of developing MetS (age and sex-adjusted incidence risk ratio (RR) = 0.98; 95% confidence interval (CI) =0.97-0.99). This association persisted after adjustment for individual-level income, education, and health behaviours. There was no significant association between area-level income and incident MetS overall. For the high income participants, however, a one standard deviation increase in median household weekly income was associated with a 29% higher risk of developing MetS (Adjusted RR = 1.29; 95%CI = 1.04-1.60).
While area-level education was independently and inversely associated with the risk of developing MetS, the association between area-level income and the MetS incidence was modified by individual-level income.