Desmintiendo el primer falso mito: “el terrorismo en el Perú ha terminado”

The above estimates are for the total Australian population; however, Australia is a multi-ethnic and multicultural society with migrants from high-risk ethnic groups, which is relevant for diabetes risk. Knowing the prevalence rates in our migrant communities and our own indigenous populations would be important; 28.5% of the estimated resident population was born overseas, or 6.9 million persons (115) and 686,800 people or 3% of the total Australian population identifies itself as Aboriginal and Torres Strait Islander in 2014 (116). Figure 3 shows the rise in the overseas born population in Australia over the years (115). Perhaps due to Australian immigration policies over the last few decades, 46% of Australians have at least one parent born overseas. Earlier migrants came predominantly from the United Kingdom, and UK migrants now account for 5.0% of Australia's total population as of the 30th of June 2016. Subsequent to this, migration from the eastern and southern European countries followed and then

migration from the Middle East and Asia. Specifically, the ABS (115) notes that the number of migrants from Nepal, Pakistan, Brazil, India and Bangladesh have had the

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highest rate of increase from 2006 to 2016. There have been progressively higher numbers of migrants from African countries in recent years and being geographically proximate, the Pacific Islands have also been a major source of migrants in the recent decade. Figure 4 shows the top 10 country of origin for overseas born people in Australia and the growth or decline of these groups of migrants in the years of 2006, 2011 and 2016.

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Figure 4: Top 10 country of origin for overseas born people in Australia and their growth or decline over 3 different years. Source: Migration, Australia (cat. no. 3412.0) (51)

The relevance is that diverse migrant groups are likely to be characterised by a differing susceptibility to diabetes and even different clinical manifestations of diabetes. Minority groups in Australia come from areas of the world with a high prevalence of type 2 diabetes signalling an ethnic specific increase in risk.

Additionally, the age structure of migrants also impacts on population risk for diabetes. For example, the ethnicities of the oldest migrant groups are shown in Table 5. It is likely that the ethnicities with a higher prevalence of older migrants have a higher

prevalence of diabetes with perhaps a longer duration of pre-existing diabetes. Migrant and ethnic specific comparative data with respect to diabetes are discussed below.

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Table 5: Oldest and youngest migrant groups, 2015 Source: The demographer’s Christmas: countdown to the census: (117; 118)

Of note is that 686,800 people or 3% of the Australian population in 2014 identified itself as Aboriginal and Torres Strait Islander (116) and there is a relative dearth of data for this indigenous Australian group. However, all information available, when compared with the general population, shows that they carry a disproportional burden of diseases, including diabetes.

In 2014 the National Aboriginal and Torres Strait Islander Social Survey (NATSISS), 2014-15 (119) found that almost half of this indigenous group were under the age of 20 years. Importantly in this survey, the authors found the prevalence of diabetes to be 12.8%, much higher than the Australian average with most diabetes being type 2 diabetes in origin. However, the authors do acknowledge that their methodology was not robust enough to provide secure prevalence data. They recommend 2012-13

National Aboriginal and Torres Strait Islander Health Survey (NATSIHS) (119; 120) data for this purpose. NATSIHS 2012-2013 is the largest biomedical survey conducted in Indigenous Australians and surveyed 3300 individuals over 18 years of age. It reported a prevalence of diabetes in this population of 11.1%, with a range of 9.4% in major cities and regional areas and 20.8% in remote areas. After adjusting for age

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non-Indigenous people to have diabetes. This survey noted that the age pattern for the prevalence of diabetes between indigenous and non-indigenous was similar but

diabetes and newly diagnosed diabetes tended to occur at a younger age in indigenous Australians. The authors found that the rate of diabetes for indigenous people aged 35- 44 years (9.0%) was equivalent to that of non-indigenous people aged 55-64 years (8.2%). Similarly, the rate for those aged 45-54 years (17.8%) was similar to those non- indigenous aged 65-74 years (15.0%). This is illustrated in Figure 5.

Figure 5: Proportion with Diabetes by Indigenous status and age (From: 4727.0.55.003 - Australian Aboriginal and Torres Strait Islander Health Survey: Biomedical Results, 2011-13)

Minges et al. in 2011 (121) performed a systematic review of the literature for studies that reported the diabetes prevalence in the Australian indigenous population. The studies were conducted between 1997 and 2010, and the diagnosis of diabetes was based on self-reports or standard diagnostic criteria. Minges found the prevalence of diabetes and impaired glucose tolerance (IGT) in Indigenous Australians to range between 3.5% to 33.1% in the 24 studies reviewed.

The current comparative data pertaining to migrant and ethnic specific diabetes prevalence are now discussed. Abouzeid et al (122) reported that using the NDSS registry and the 2006 Australian National Census data in the state of Victoria in

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Australia, in all migrant groups, the odds of them developing type 2 diabetes versus those who were Australian born was higher, even after adjusting for age and socio- economic strata. In this study, the groups from the Pacific Islands, Southern and Central Asia, North Africa and Middle East had the highest odds ratio (OR) of diabetes compared to the reference group. For example, the OR for persons born in the Pacific Islands is 6.3 for men and 7.2 for women compared to the Australian born reference group. These are illustrated further in Tables 6 and 7.

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Table 6: Crude and Adjusted prevalence rates for males with Type 2 diabetes. Table from Abouzeid et al. (114)

Table 7: Crude and Adjusted prevalence rates for females with Type 2 diabetes. Table from Abouzeid et al. (122)

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The authors in this work stated that the reference group, the Australian born group included Indigenous people, who are known to have a higher prevalence of diabetes, and thus may have artificially lowered the prevalence OR for other ethnicities reported. However, the authors further mention that they were unable to analyse the Indigenous group separately due to uncertainty over the demographic characteristics of this population in Victoria. They argue that the National Census for Victoria in 2006 only identified 0.6% of the population as Indigenous and thus their inclusion would not

greatly impact on the overall prevalence OR reported. Furthermore, this work could only account for first generation migrants because the NDSS only records country of birth rather than ethnicity data. The implication is that many of the Australian born in the reference group would be second or more generation migrants, but the authors were not able to distinguish. This issue may also mean that the OR reported are an underestimate of the relative prevalence of diabetes in migrant and indigenous communities in Australia.

The origin of this migrant specific excess risk of diabetes is not entirely clear. Of course, genetic predisposition may account for differences in risk. It has also been postulated that an increase in BMI, as a result of greater economic prosperity achieved upon migration to Australia, may also be a factor (123; 124). Montesi et al. (125)

suggest that lower the social, economic status in the country of origin the higher the risk of the population to become obese in the new country, further exacerbating any

background ethnicity specific predispositions to diabetes.

In addition to the migrant prevalence data presented above, in terms of ethnicity alone irrespective of migrant status, there are few Australian data that examine this. McGill and Twigg (126) in 2012 pointed out in an audit of more than 9000 patients in Sydney that in all non-Caucasian groups, the diabetes diagnosis occurred at a significantly

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younger age than in Caucasian groups and that they had poorer blood glucose control and higher rates of microvascular and in some cases macrovascular complications such as higher prevalence of retinopathy and ischaemic heart disease. In the Fremantle Diabetes Study, the prevalence of type 2 diabetes in Asian patients was similar to the background population; however, these Asian patients with diabetes were younger and less obese. The researchers also found that these patients had a higher prevalence of retinopathy despite accounting for similar diabetes control and duration; 27.3% for Asians vs 13.5% for Anglo-Celtic (127).

Despite the established multi ethnic composition of the Australian population, there are few data on the multi ethnic differences in diabetes outcomes in Australia and, in particular, mortality data are lacking. In this context, using a single centre eHR, ethnic specific differences in complications and survival are explored further in this thesis in

chapter 3. The potential confounding from geographic variation in the treatment of

diabetes and risk factors on mortality, in addition to variations in access to care, are attenuated by exploring data from a single site.