The cost of diabetes in adults in Australia
Introduction
The global diabetes epidemic shows no signs of slowing [1]. Reliable costing data are required to assist policy makers in making informed decisions about future health policy and budgets. The International Diabetes Federation previously estimated total healthcare expenditures due to diabetes in 2010 for countries with appropriate health expenditure data [2]. Although their estimates were comparable to those reported by some countries, the estimates do not reflect the total healthcare cost of people with diabetes since they did not include expenditures not associated with diabetes.
In Australia, approximately 1.0 million people aged ≥25 years had diabetes in 2000 and this is projected to reach 2.0–2.9 million by 2025 [3]. Previous economic impact studies such as that undertaken by the Australian Institute of Health and Welfare [4] applied a ‘top down’ approach where the cost of a disease such as diabetes is obtained by apportioning known total healthcare costs according to the attributable fraction of the disease. This approach, however, may not reflect the total cost incurred by people with the disease since costs not directly associated with the disease are not considered in the estimation. A method which takes into account all healthcare expenses borne by an individual with a disease is the ‘bottom up’ approach where cost data from individuals are collected and extrapolated to the cost to society. The DiabCo$t study applied the ‘bottom up’ approach but relied on self-reported co-morbidity data and did not include a non-diabetic comparison group [5].
The Australian Diabetes, Obesity and Lifestyle study (AusDiab) is the largest Australian population-based study on diabetes and its complications [6]. The initial AusDiab survey was conducted in 1999–2000 with individual data on the use of health services and health related expenditure collected in a 5 year follow-up of the baseline cohort in 2004–2005. These data provided an opportunity to compare costs in people with and without diabetes and lesser forms of glucose intolerance in Australia. The aim of this study was to use data collected in the AusDiab follow-up study to perform a comparative costing analysis in people with different glucose tolerance status using the more robust ‘bottom up’ approach.
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Study participants
In 1999–2000, 11247 adults aged ≥25 years participated in the AusDiab baseline study. In 2004–2005, 6400 of those participants attended the 5-year follow-up survey. Details of the study have been published elsewhere [6], [7]. The current study included participants with glucose tolerance status data and cost data collected in 2004–2005. Glucose tolerance was classified according to the World Health Organization diagnostic criteria [8]. Known diabetes included participants who answered yes to
Characteristics of participants
A total of 6101 participants [54.0% females; mean (SD) age = 56.6 (12.7) years; mean BMI = 27.7 (5.1) kg/m2] were included in the analysis. According to glucose tolerance status in 2004–2005, 6.0% had known diabetes, 3.1% had newly diagnosed diabetes, 9.1% had impaired glucose tolerance (IGT), 4.8% had impaired fasting glucose (IFG) and 77.0% had normal glucose tolerance (NGT). Compared with the entire cohort, those with diabetes were older [mean age = 63.9 (11.4) years], more overweight [mean BMI =
Discussion
The annual direct cost of diabetes in 2005 for the Australian population aged ≥30 years was A$4.4 billion and a further A$6.2 billion was spent on government subsidies making a total of A$10.6 billion. In 2010 dollars, this equates to A$14.6 billion.
The estimated costs increased as glucose intolerance progressed from NGT to IGT and diabetes, except for IFG where the costs were not significantly different to NGT. The reason for the lack of difference in health related expenditure between people
Conflict of interest
The authors declare that they have no conflict of interest.
Acknowledgements
This research was supported by a Diabetes Australia Research Trust grant and an unrestricted grant from Sanofi-Aventis Australia. C Lee and A Cameron are supported by NHMRC training fellowships. R Colagiuri is a Medical Foundation Fellow. J Shaw has a NHMRC Senior Research Fellowship. The AusDiab study co-coordinated by the Baker IDI Heart and Diabetes Institute, gratefully acknowledges the generous support given by:
National Health and Medical Research Council (NHMRC grant 233200), Australian
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