Projected socioeconomic disparities in the prevalence of obesity among Australian adults

Objective: To project prevalence of normal weight, overweight and obesity by educational attainment, assuming a continuation of the observed individual weight change in the 5-year follow-up of the national population survey, the Australian Diabetes, Obesity and Lifestyle study (AusDiab; 2000–2005).

Methods: Age-specific transition probabilities between BMI categories, estimated using logistic regression, were entered into education-level-specific, incidence-based, multi-state life tables. Assuming a continuation of the weight change observed in AusDiab, these life tables estimate the prevalence of normal weight, overweight and obesity for Australian adults with low (secondary), medium (diploma) and high (degree) levels of education between 2005 and 2025.

Results: The prevalence of obesity among individuals with secondary level educational attainment is estimated to increase from 23% in 2000 to 44% in 2025. Among individuals with a degree qualification or higher, it will increase from 14% to 30%. If all current educational inequalities in weight change could be eliminated, the projected difference in the prevalence of obesity by 2025 between the highest and lowest educated categories would only be reduced by half (to a 6 percentage point difference from 14 percentage points).

Conclusion: We predict that almost half of Australian adults with low educational status will be obese by 2025. Current trends in obesity have the potential to drive an increase in the absolute difference in obesity prevalence between educational categories in future years.

Implications: Unless obesity prevention and management strategies focus specifically on narrowing social inequalities in obesity, inequalities in health are likely to widen.

Incidence of cardiovascular risk factors by education level 2000-2005 : the Australian diabetes, obesity and lifestyle (AusDiab) cohort study

Lower socioeconomic status (SES) is associated with a higher prevalence of major risk factors for cardiovascular disease (CVD). However, few longitudinal studies have examined the association between SES and CVD risk factors over time. We aimed to determine whether SES, using education as a proxy, is associated with the onset of CVD risk factors over 5 years in an Australian adult cohort study.

Participants in the Australian Diabetes, Obesity and Lifestyle study (AusDiab) study aged 25 years and over who attended both baseline and 5-year follow-up examinations (n=5 967) were categorised according to educational attainment. Cardiovascular risk factor data at both time points were ascertained through questionnaire and physical measurement.

Women with lower education had a greater risk of progressing from normal weight to overweight or obesity than those with higher education (age-adjusted OR 1.57, 95% CI 1.06-2.31). Both men and women with lower education were more likely to develop diabetes (age-adjusted OR from higher education 1.75, 95% CI 1.14-2.71 and 3.01, 95% CI 1.26-7.20, respectively). A lower level of education was associated with a greater number of risk factors accumulated over time in women (OR of progressing from having two or less risk factors at baseline to three or more at follow up, 2.04, 95% 1.32-3.14).

In this Australian population-based study, lower educational attainment was associated with an increased risk of developing both individual and total CVD risk factors over a 5-year period. These findings suggest that SES inequalities in CVD will persist into the future.

Best practice for prevention and treatment of cardiovascular disease through an equity lens : a review

Background Despite declining rates of cardiovascular disease (CVD) mortality in developed countries, lower socioeconomic groups continue to experience a greater burden of the disease. There are now many evidence-based treatments and prevention strategies for the management of CVD and it is essential that their impact on the more disadvantaged group is understood if socioeconomic inequalities in CVD are to be reduced.

Aims To determine whether key interventions for CVD prevention and treatment are effective among lower socioeconomic groups, to describe barriers to their effectiveness and the potential or actual impact of these interventions on the socioeconomic gradient in CVD.

Methods Interventions were selected from four stages of the CVD continuum. These included smoking reduction strategies, absolute risk assessment, cardiac rehabilitation, secondary prevention medications, and heart failure self-management programmes. Electronic searches were conducted using terms for each intervention combined with terms for socioeconomic status (SES).

Results Only limited evidence was found for the effectiveness of the selected interventions among lower SES groups and there was little exploration of socioeconomic-related barriers to their uptake. Some broad themes and key messages were identified. In the majority of findings examined, it was clear that the underlying material, social and environmental factors associated with disadvantage are a significant barrier to the effectiveness of interventions.

Conclusion Opportunities to reduce socioeconomic inequalities occur at all stages of the CVD continuum. Despite this, current treatment and prevention strategies may be contributing to the widening socioeconomic-CVD gradient. Further research into the impact of best-practice interventions for CVD upon lower SES groups is required.

Acute rheumatic fever associated with household crowding in a developed country

Background: Acute rheumatic fever (ARF) and its sequelae, chronic rheumatic heart disease, remain important causes of morbidity and mortality worldwide, but there is little recent information about risk factors. The aim of this study was to examine the association between ARF and household crowding in New Zealand between 1996 and 2005.

Methods: This ecologic study used hospitalization data and census data to calculate incidence rates by census area unit (CAU). Rates of ARF were examined in relation to individual factors (age, ethnicity) and area factors based on the CAU of home address (household crowding, New Zealand deprivation index, household income, and proportion of children aged 5–14 years). The multivariate relationship between ARF incidence and CAU-based variables was assessed using a zero-inflated negative binomial model.

Results: This study included 1249 new cases of ARF between 1996 and 2005. At the univariate level, ARF rates were associated with household crowding across all age groups and ethnicities. ARF rates were significantly and positively related to household crowding after controlling for age, ethnicity, household income, and the density of children in the neighborhood. The incidence rate ratio was 1.065 (95% confidence interval, 1.052–1.079) for the total population.

Conclusions: In New Zealand, ARF rates are associated with household crowding at the CAU level. This finding supports action to reduce household crowding to improve health and reduce health inequalities. Our conclusion could be further investigated using a case-control study.

Sacrificial girls : a case study of the impact of streaming and setting on gender reform

This article reports on research funded by the Australian Research Council to investigate school responses to gender equity. It addresses the efforts of a disadvantaged school to tackle what they perceived to be gender inequalities, but in the process of constructing a top-set and bottom-set/ stream class they are developing new forms of old inequalities and new forms of inequalities. This research indicates that despite popular assertions that girls’ education has become the priority of schools and education systems, girls are being further disadvantaged through attempts to implement market strategies coupled with gender reform agendas grounded in liberal notions of equity and relying on unsophisticated notions of affirmative action. In addition, this study highlights the extent to which a media-driven debate about boys’ education has influenced the constitution of boys as the ‘new disadvantaged’ with the capacity to determine the nature of gender reform agendas and programmes in schools.

Exponential stabilization for state and input delay systems via output feedback

This paper considers the exponential stabilization problem via static and dynamic output feedback controllers of linear systems with a time delay in both the state and input. By using a change of the state variable and combining with the Lyapunov-Krasovskii method, new sufficient conditions for exponential stabilization via static and dynamic output feedback controllers are proposed. The conditions are expressed in terms of matrix inequalities but with only one parameter needs to be tuned and therefore can be efficiently solved by incorporating an one-dimensional search method into the Matlab’s LMI toolbox. Two numerical examples are provided to illustrate the obtained results.

Observer-based controller design of time-delay systems with an interval time-varying delay

This paper considers the problem of designing an observer-based output feedback controller to exponentially stabilize a class of linear systems with an interval time-varying delay in the state vector. The delay is assumed to vary within an interval with known lower and upper bounds. The time-varying delay is not required to be differentiable, nor should its lower bound be zero. By constructing a set of Lyapunov–Krasovskii functionals and utilizing the Newton–Leibniz formula, a delay-dependent stabilizability condition which is expressed in terms of Linear Matrix Inequalities (LMIs) is derived to ensure the closed-loop system is exponentially stable with a prescribed α-convergence rate. The design of an observerbased output feedback controller can be carried out in a systematic and computationally efficient manner via the use of an LMI-based algorithm. A numerical example is given to illustrate the design procedure.

An examination of the mediating role of salt knowledge and beliefs on the relationship between socio-demographic factors and discretionary salt use: a cross-sectional study

Background Discretionary salt use varies according to socio-demographic factors. However, it is unknown whether salt knowledge and beliefs mediate this relationship. This study examined the direct and indirect effect of socio-demographic factors on salt knowledge and discretionary salt use in a sample of 530 Australian adults.

Methods An internet based cross-sectional survey was used to collect data for this study. Participants completed an online questionnaire which assessed their salt knowledge, beliefs and salt use behaviour. Mplus was used to conduct structural equation modelling to estimate direct and indirect effects.

Results The mean age of the participants was 49.2 years, and about a third had tertiary education. Discretionary salt use was inversely related to age (r=-0.11; p<0.05), and declarative salt knowledge (knowledge of factual information) scores (r = -0.17; p<0.01), but was positively correlated with misconceptions about salt (r = 0.09; p<0.05) and beliefs about the taste of salt (r = 0.51; p<0.001). Structural equation modelling showed age, education and gender were indirectly associated with the use of discretionary salt through three mediating pathways; declarative salt knowledge, misconceptions about salt and salt taste beliefs.

Conclusions Inequalities observed between socio-demographic groups in their use of discretionary salt use can potentially be reduced through targeted salt knowledge and awareness campaigns.

Commentary : Obesity - why governments must act

The commercial drivers of the obesity epidemic are so influential that obesity can be considered a robust sign of commercial success – consumers are buying more food, more cars, and more energy-saving machines (1). It is unlikely that these powerful economic forces will change sufficiently in response to consumer desires to eat less and move more, or to corporate desires to be more socially responsible. When the 'free market' creates substantial population detriments and health inequalities, government policies are needed to change the ground-rules in favour of population benefits.

Design of H∞ control of neural networks with time-varying delays

This paper deals with the H∞ control problem of neural networks with time-varying delays. The system under consideration is subject to time-varying delays and various activation functions. Based on constructing some suitable Lyapunov-Krasovskii functionals, we establish new sufficient conditions for H∞ control for two cases of time-varying delays: (1) the delays are differentiable and have an upper bound of the delay-derivatives and (2) the delays are bounded but not necessary to be differentiable. The derived conditions are formulated in terms of linear matrix inequalities, which allow simultaneous computation of two bounds that characterize the exponential stability rate of the solution. Numerical examples are given to illustrate the effectiveness of our results.

Observer-based control for time-varying delay neural networks with nonlinear observation

This paper studies the problem of designing observer-based controllers for a class of delayed neural networks with nonlinear observation. The system under consideration is subject to nonlinear observation and an interval time-varying delay. The nonlinear observation output is any nonlinear Lipschitzian function and the time-varying delay is not required to be differentiable nor its lower bound be zero. By constructing a set of appropriate Lyapunov-Krasovskii functionals and utilizing the Newton-Leibniz formula, some delay-dependent stabilizability conditions which are expressed in terms of Linear Matrix Inequalities (LMIs) are derived. The derived conditions allow simultaneous computation of two bounds that characterize the exponential stability rate of the closed-loop system. The unknown observer gain and the state feedback observer-based controller are directly obtained upon the feasibility of the derived LMIs stabilizability conditions. A simulation example is presented to verify the effectiveness of the proposed result.

Demographic and socio-cultural correlates of medical mistrust in two Australian states:Victoria and South Australia

Studies on medical mistrust have mainly focused on depicting the association between medical mistrust and access/utilization of healthcare services. The effect of broader socio-demographic and psycho-social factors on medical mistrust remains poorly documented. The study examined the effect of broader socio-demographic factors, acculturation, and discrimination on medical mistrust among 425 African migrants living in Victoria and South Australia, Australia. After adjusting for socio-demographic factors, low medical mistrust scores (i.e., more trusting of the system) were associated with refugee (β=−4.27, p<0.01) and family reunion (β=−4.01, p<0.01) migration statuses, being Christian (β=−2.21, p<0.001), and living in rural or village areas prior to migration (β=−2.09, p<0.05). Medical mistrust did not vary by the type of acculturation, but was positively related to perceived personal (β=0.43, p<0.001) and societal (β=0.38, p<0.001) discrimination. In order to reduce inequalities in healthcare access and utilisation and health outcomes, programs to enhance trust in the medical system among African migrants and to address discrimination within the community are needed.