Introduction
Murray Epstein, MD: Good afternoon. My name is Dr. Murray Epstein, from the University of Miami, and I'd like to welcome you to this Medscape program on a very interesting topic: the issue of the Australian Aboriginal people and end-stage kidney failure. This is not just a unique microcosm but, I think, a very important lesson that we can learn here -- outside of Australia -- with respect to healthcare delivery and this unique disease, which is so prevalent in certain parts of Australia.
We have as our guest this afternoon Professor Mark Thomas, who is the consultant nephrologist at the Royal Perth Hospital in Western Australia and who has devoted much of his academic career to studying the problem and to essentially enhancing healthcare delivery to this deprived population. Mark, welcome to the program.
Mark A. Thomas, MBBS: Thank you, Murray.
Trend in Kidney Disease in the Aboriginal Population
Dr. Epstein: Perhaps we can start off by looking at specific issues, and, initially, you could share with us the rates and trends with respect to kidney disease in this deprived population.
Dr. Thomas: Thank you. A lot of people don't realize just how much more frequent kidney disease is in the Australian Aboriginal population, sometimes also referred to by the abbreviation ATSI, standing for the Aboriginal and Torres Strait Islander population. Whereas in the general Australian population we have a new end-stage kidney failure rate of around 100 per million, in the Aboriginal population, overall, it's up to 800 and sometimes even 1500 cases per million. It does vary quite a lot around Australia.
Dr. Epstein: Are there trends that you can share with us with respect to when this problem was identified and loomed to the foreground, and why this was?
Dr. Thomas: Well, [the trend] really didn't emerge until the mid-1980s, when it rose steadily through to the end of the 1990s and has plateaued thereafter, but there is quite an interstate variation. We find that some states within Australia have instances as low as 300 cases per million, and in other cases, up in the Northern territories of Australia, we can have rates as high as nearly 2000-2300 cases per million, so there is an enormous geographic variation as well variation over time.
Aboriginal Subgroups and Disparities Among Them
Dr. Epstein: Can you shed some light on the reasons for this disparity?
Dr. Thomas: Well, often it tracks just the numbers of Aboriginal patients in that area, but even factoring per million population of that particular race, it still is disproportionately high, and so that may have to do with the mixture with the Caucasian population and also the differences as you get further away from metropolitan areas. It's almost the reversal of what you might expect, where you have a metropolitan area with access to high diagnostic facilities and where you would expect to find more of the disease, whereas you actually see the reverse in the Australian situation.
Dr. Epstein: You essentially subserve the Aboriginal population outside of Perth and Western Australia. You infer that there are differences between the Aboriginals in the Northern territories vs the Aboriginals in Western Australia. To what does that relate? Is it mostly the admixture or are there other issues that contribute to this?
Dr. Thomas: There are what they describe as different skin groups.
Dr. Epstein: Can you perhaps define that for our audience? Because I think that's an unusual term that I myself have not heard before.
Dr. Thomas: There are subdivisions of tribes and then broader classifications of skin groups. In Western Australia we have the Nyoongar tribes and the Wongi people. Then over on the East coast there are the Koori people, and each of the Aboriginal families will identify within a tribe and then within their skin groups if they follow the traditional lifestyles, but those who have lived in the metropolitan areas for longer were more acculturated and may even be 1/16 or so from the original tribal groups. For a definition of aboriginality, we leave it entirely as self-determined. If you describe yourself as Aboriginal, then you are Aboriginal.
Dr. Epstein: For Aboriginal families that have migrated from the hinterland, from the rural areas to cities, to Melbourne to Brisbane, you mention that this major problem really achieved recognition in the 1980s, so there has not been sufficient time to address the question as to whether acculturation and migration have altered propensity to susceptibility to kidney failure.
Dr. Thomas: We're not quite sure what all the drivers were, but a lot of it has to do with lifestyle and the trends of obesity, diabetes, and smoking rates, much more so than any move. The incidence of these risk factors in [all] Northern territory Aboriginals are basically the same as those of the Northern territory Aboriginals who have been stable in that area for so long. This is the same for the Western Australia Aboriginals. There haven't been recent moves to explain this change in trends.
Socioeconomic Status and Drivers for Kidney Disease in Aboriginal Groups
Dr. Epstein: Interestingly, if we look at the nexus of ethnicity in the kidney, for want of a broader term, if we look at some of our Native American population here in United States and the studies that we're aware of on Pima Indians and so on, socioeconomic duress status -- addictions if you will -- has played a role in that increased propensity, certainly for diabetes. Could you perhaps expound on that with respect to the Australian Aboriginal population?
Dr. Thomas: If we use the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) registry, which has been such a useful source of data for us, we can say that the clear obvious drivers of this tend to be age related (it's much more of a middle-aged person's disease), sex related (it tends to be affecting more females than males), and it's very much economic-place related. Looking at a graph relating disadvantage to end-stage kidney failure incidence (Figure 1), when they took some of the remote-area communities and then tried to derive an index of socioeconomic disadvantage, they weren't able to find an index that went down low enough to register just how poor the communities were. But when they ranked them from 1 to 32, they discovered that it exactly paralleled the rate of renal failure. So, starting at a rate of 1, which is the standardized incidence ratio for the normal Australian population, the most disadvantaged population had a rate of renal failure that was 32 times greater.
To understand how poor these communities are in terms of deprivation from the basic services, if you took the midpoint of that group, which would have a rate of renal disease of about 1000, which is 10 times the normal metropolitan rate, that corresponds to 50% of the school drop-outs leaving before the age of 15 (Figure 2). Seventy-five percent of the people in this midrange community are unemployed, with more than two and a half people in each bedroom, with an average income of less than 75 Australian dollars per person, and more than 15% of the babies are under 2.5 kilos. They are astoundingly and embarrassingly awful lifestyles and demographics to have in what we regard as a first-world country.
Dr. Epstein: Has the Australian government, or the government of Western Australia, taken measures to close the gap there?
Dr. Thomas: Closing the gap is very much a key focus of the health industry, of the government housing industry, of the welfare industries, and it's not been an easy job, but it's certainly something that everybody tries to do.
Dr. Epstein: Thank you very much. That was a very helpful overview of what the scope of the problem is and what some of the determinants are of these problems.