By Andrew Tan
Hayes A, Tan EJ, Killedar, Lung T. Socioeconomic inequalities in obesity: modelling future trends in Australia. BMJ Open 2019: forthcoming.
Why we studied this topic
In high income countries, including USA, UK, Canada and Australia, a higher burden of obesity is seen in lower socioeconomic groups. However, the current literature is mixed on whether inequalities in obesity are persistent, widening or narrowing over time.
People generally accrue BMI during their life course and, as a result, there has been great interest in identifying BMI trajectories through longitudinal studies or modelling BMI growth trajectories to understand the epidemiology of disease and to identify at-risk populations. Beyond their value in epidemiological studies, models are regarded as powerful tools for informing policy decisions, yet current models of obesity rarely take account of socioeconomic position (SEP), thus overlooking a key policy-relevant determinant of obesity.
There are currently few analytical tools to evaluate which interventions are most effective in reducing inequalities. Simulation models may provide insights in this context that are not possible with traditional statistical methods but their use is just beginning.
What this paper adds
We developed a new version of a microsimulation model for Australia adults, which projects obesity in different socioeconomic subgroups, based on educational attainment. Accordingly, in this study, we validate our model projections against observed BMI trajectories and obesity progression, stratified by SEP, and then use the model to determine future trends in socioeconomic inequalities in obesity —both within and between generations. In other words, we predicted future obesity and severe obesity for different birth cohorts, born 10 years apart.
What was surprising
While our results suggest that lower SEP groups have higher burden of obesity, we also found that more recent birth cohorts are at higher risk of obesity and severe obesity, and its consequences in middle age.
What it means for policy/ practice
Our model provides a framework for further research to investigate which interventions will be most effective in narrowing the gap in socioeconomic disparities in obesity in adulthood. Prevention efforts should focus on these vulnerable population groups in order to avoid future disparities in health outcomes.