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A new study published in the Medical Journal of Australia examines the complex interplay of socio-economic position with ten of Australia’s most prevalent chronic diseases.
Dr Joanna Y Gong and colleagues analysed data from the 2021 Australian national census to determine the prevalence of arthritis, asthma, cancer, dementia, diabetes, heart disease, kidney disease, lung disease, mental health conditions, and stroke by socio-economic position.
They found that the prevalence of chronic disease differed by socio-economic position, but the direction, magnitude, and consistency of the effect differed by disease, socio-economic position measure, age, and sex.
“Establishing which chronic diseases are associated with socio-economic position is integral to developing more effective health interventions,” Dr Gong and co-authors wrote.
“However, many studies investigating links between socio-economic position and health have been subject to selection bias.”
“Our aim was to determine whether ten chronic diseases for which census data were available differed by area- and individual-level measures of socio-economic position.”
Lower socio-economic position takes a toll
The data for 11.3 million people aged 40 years and older was included in the study, which measured socio-economic position by Index of Relative Socio-economic Disadvantage (IRSD), income category, educational level and occupational grade.
The prevalence of nine of ten included diseases (with cancer as the exception) increased with socio-economic disadvantage for people aged 40–59 or 60–79 years, with lung disease having the greatest prevalence for both men and women.
For people aged 40–59 or 60–79 years, the increase in age-standardised chronic disease prevalence by lower income category was greatest for dementia in both women and men.
For people aged 80 years or older, the increase in disease prevalence per IRSD decile decrease and lower income category was greatest for kidney disease in women and for mental health conditions in men.
The prevalence of diabetes also generally increased with lower socio-economic position.
Some unexpected findings
The prevalence of cancer decreased with increasing socio-economic disadvantage in most sex-specific age groups, which could relate to differences in access to cancer screening and detection, as well as the types of cancer which are more frequently diagnosed being associated with higher economic position (eg, breast cancer).
“Lower cancer prevalence could partly reflect higher case fatality, and therefore does not reduce the need for better health interventions for people of lower socio-economic position,” the authors wrote.
Educational level and occupational grade did not consistently influence the prevalence of chronic disease, and an unexpected finding was that the burden of chronic disease was not greatest for people without formal educational qualifications.
“This finding might be explained by lower health literacy and health care-seeking behaviour, leading to lower rates of disease detection,” the authors wrote.
“Conversely, the people in this group could be healthier than those with secondary schooling to year nine or below. For example, shift-and-persist strategies in some people of lower socio-economic position can contribute to better physical health, suggesting that more resilience protects the health of some people of lower socio-economic position.”
Targeted health interventions needed
The authors hope that by understanding the relationship between different socio-economic position measures and chronic diseases, directed interventions can be formulated.
“The influence of socio-economic position was more marked for women than men; despite some specific health interventions for women, further strategies are needed,” the authors wrote.
“Differences in the prevalence of some diseases by socio-economic position were especially marked, with some variation across age groups.”
“Groups at particular risk of these chronic diseases should be targeted by health interventions for reducing socio-economic inequalities in health.”
Read the research in the Medical Journal of Australia.
Annika Howells is the sub-editor of the MJA’s InSight+.
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