CHRONIC KIDNEY DISEASE

Kidney disease is a chronic disease in which a person's kidney function is reduced or damaged. This affects the kidney's ability to filter blood and therefore control the body's water and other hormone levels, leading to increased fluid and waste within the body.¹ Kidney disease is also associated with several other chronic diseases such as diabetes and cardiovascular disease.

Diseases of the urinary system were the 10th leading cause of death for Aboriginal and Torres Strait Islander people in 2012. The age-standardised death rate for urinary diseases was two and a half times higher for Aboriginal and Torres Strait Islander people than for non-Indigenous people.²

Chronic kidney disease has a number of stages, ranging in severity from Stage 1 to Stage 5, with the early stages often showing no symptoms. An individual's kidney function can improve or regress during the early stages of the disease but once Stages 4 and 5 are reached, kidney function is severely reduced and unlikely to improve. A person with end stage kidney disease is generally reliant on kidney replacement therapy in the form of dialysis or kidney transplant.^1,3

Data source and definitions The National Aboriginal and Torres Strait Islander Health Measures Survey (NATSIHMS) measured two aspects of kidney function: estimated glomerular filtration rate (eGFR) and the presence of albuminuria. Chronic kidney disease stages were then determined by combining the participants' eGFR results with their albumin creatinine ratio (ACR) results. The different stages were defined as follows: No indicators of chronic kidney disease - eGFR ≥60 mL/min/1.73 m² and no presence of albuminuria Stage 1 - eGFR ≥90 mL/min/1.73 m² & albuminuria Stage 2 - eGFR 60–89 mL/min/1.73 m² & albuminuria Stage 3a - eGFR 45–59 mL/min/1.73 m² Stage 3b - eGFR 30–44 mL/min/1.73 m² Stage 4–5 - eGFR <30 mL/min/1.73 m² The NATSIHMS test results only indicate a stage of chronic kidney disease as further testing would be required for a diagnosis. Note that people who live in non-private dwellings, such as hostels, hospitals or nursing homes were not in the scope of the survey. This may affect estimates of the number of people with some conditions; for example, conditions which may require periods of hospitalisation, such as kidney disease.

In 2012–13, almost one in five (17.9%) Aboriginal and Torres Strait Islander people aged 18 years and over had indicators of chronic kidney disease, with the majority being in Stage 1 (11.8%) and very few in Stages 4–5 (1.1%). Overall, the rates of chronic kidney disease were similar for Aboriginal and Torres Strait Islander men (18.9%) and women (16.9%).

After taking age differences into account, Aboriginal and Torres Strait Islander people were more than twice as likely as non-Indigenous people to have indicators of chronic kidney disease (rate ratio of 2.1). They were three times as likely as their non-Indigenous counterparts to have indicators of Stage 1 chronic kidney disease and more than four times as likely to have Stages 4–5 (rate ratio of 4.6).

Among those Aboriginal and Torres Strait Islander people who had indicators of chronic kidney disease in the NATSIHMS, 11.2% self-reported having the condition. Although this rate is significantly higher than that for the non-Indigenous population (where 6.0% with indicators of chronic kidney disease self-reported having the condition), these results still indicate that around nine in ten Aboriginal and Torres Strait Islander people with signs of kidney disease were not aware they had it.

However, this is not unexpected as unlike other tests for chronic disease, results for albuminuria or abnormal eGFR alone cannot provide a diagnosis for kidney disease and could instead indicate the presence of an acute kidney condition or infection. Kidney disease can only be confirmed if albuminuria or eGFR of less than 60 mL/min/1.73 m² are persistent for at least three months.⁴ The majority (69.8%) of people with indicators of chronic kidney disease who self-reported the condition had test results that indicated they were in the later stages of the disease (Stages 3 to 5).

Rates of chronic kidney disease were particularly high for Aboriginal and Torres Strait Islander people living in remote areas in 2012–13, where around three in every ten (33.6%) people had indicators of the disease. This compared with just over one in ten (13.1%) living in non-remote areas.

Overall, the prevalence of chronic kidney disease in the Aboriginal and Torres Strait Islander population steadily increased with age from early adulthood, whereas in the non-Indigenous population, levels of kidney disease remained very flat until late adulthood and only began to increase from the age of 65.



The higher prevalence of chronic kidney disease in the Aboriginal and Torres Strait Islander population may be due to the high prevalence of traditional chronic kidney disease risk factors, including diabetes and high blood pressure.¹ Diabetes is the most common cause of chronic kidney disease as, over time, high blood glucose levels can damage the filtering units within the kidneys.⁵ In the NATSIHMS, almost four in ten (37.7%) Aboriginal and Torres Strait Islander people with chronic kidney disease also had diabetes. This compared with less than one in ten (6.4%) people without chronic kidney disease.

High blood pressure is another important risk factor for chronic kidney disease as high blood pressure can damage the blood vessels supplying the kidneys.⁶ In 2012–13, Aboriginal and Torres Strait Islander people with high blood pressure were more than twice as likely to have indicators of chronic kidney disease compared with those who had normal blood pressure (29.4% compared with 14.9%).

Obesity was also associated with higher rates of chronic kidney disease in 2012–13. Around two in ten (20.1%) Aboriginal and Torres Strait Islander people who were obese had indicators of chronic kidney disease compared with just over one in ten (12.7%) people who were normal weight or underweight. Interestingly, however, this relationship between obesity and chronic kidney disease was not evident in the non-Indigenous population.⁷

For more information on chronic kidney disease, see Tables 1, 3, 4, 5, 6, 7, 10 and 17 on the Downloads page of this publication.

ENDNOTES

1 Kidney Health Australia, July 2014, Risk factors and symptoms of Kidney Disease?, <http://www.kidney.org.au/KidneyDisease/RiskFactorsandSymptoms/tabid/819/Default.aspx>,
2 Australian Bureau of Statistics, July 2014, Causes of Death Australia, ABS cat. no. 3303.0, <https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/3303.0~2012~Main%20Features~Leading%20Causes%20of%20Death~10001>,
3 The Renal Association, July 2014, Stage 4-5 CKD, <http://www.renal.org/information-resources/the-uk-eckd-guide/stages-4-5-ckd#sthash.sHNUuIjf.puzWwFtZ.dpbs>,
4 Kidney Health Australia, Jun 2013, Chronic Kidney Disease (CKD) Management in General Practice. 2nd Edition 2012 <http://www.kidney.org.au//LinkClick.aspx?fileticket=vfDcA4sEUMs%3d&tabid=635&mid=1584>,
5 Kidney Health Australia, July 2014, Diabetes and Chronic Kidney Disease (CKD), <http://www.kidney.org.au/ForPatients/Management/DiabetesandCKD/tabid/704/Default.aspx>,
6 Australian Institute of Health and Welfare, Jun 2013, An overview of Chronic Kidney Disease in Australia, 2009 <http://www.aihw.gov.au/WorkArea/DownloadAsset.aspx?id=6442459911>,
7 Australian Bureau of Statistics, July 2014, Australian Health Survey: Biomedical Results for Chronic Diseases, 2011-12, ABS cat. no. 4364.0.55.005, <https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4364.0.55.005Chapter4002011-12>,Back to top