Judith M. Katzenellenbogen

The Prevalence and Identification of Risk Factors for NIDDM in Urban Africans in Cape Town, South Africa

OBJECTIVE To determine the prevalence of NIDDM and associated risk factors in urban Africans in Cape Town, South Africa. RESEARCH DESIGN AND METHODS With a three-stage, proportional, stratified, random cluster method, we sampled 1000 Africans, > 30 yr of age, living in African residential areas in Cape Town. We assessed glucose tolerance with a 75-g oral glucose tolerance test, according to World Health Organization criteria, and obtained anthropometric and demographic data. RESULTS The response rate was 79%. The prevalence of NIDDM was 8.0% (confidence interval 5.8–10.3%), age-adjusted to world population figures and that of impaired glucose tolerance, 7.0% (confidence interval 4.9–9.1%). Multivariate analysis indicated that increased age (odds ratio 4.18), upper-segment fat distribution (odds ratio 2.94), proportion of life spent in an urban area (odds ratio 2.32), and obesity (odds ratio 2.31) were significant independent risk factors for NIDDM. In contrast, sex, family history, alcohol intake, and physical activity were not independent risk factors. Only increased age (odds ratio 4.06) was a significant risk factor for impaired glucose tolerance. CONCLUSIONS The prevalence of NIDDM in urban Africans in Cape Town, South Africa, is moderately high, and considerably higher than previous reports from Africa. The association of NIDDM with urbanization has important implications in view of the large-scale urbanization occurring in southern Africa.

Incidence of and Case Fatality Following Acute Myocardial Infarction in Aboriginal and Non-Aboriginal Western Australians (2000–2004): A Linked Data Study

BACKGROUND Despite Coronary Heart Disease exacting a heavy toll among Aboriginal Australians, accurate estimates of its epidemiology are limited. This study compared the incidence of acute myocardial infarction (AMI) and 28-day case fatality (CF) among Aboriginal and non-Aboriginal Western Australians aged 25-74 years from 2000-2004. METHODS Incident (AMI hospital admission-free for 15 years) AMI events and 28-day CF were estimated using person-based linked hospital and mortality data. Age-standardised incidence rates and case fatality percentages were calculated by Aboriginality and sex. RESULTS Of 740 Aboriginal and 6933 non-Aboriginal incident events, 208 and 2352 died within 28 days, respectively. The Aboriginal age-specific incidence rates were 27 (males) and 35 (females) times higher than non-Aboriginal rates in the 25-29 year age group, decreasing to 2-3 at 70-74 years. The male:female age-standardised incidence rate ratio was 2.2 in Aboriginal people 25-54 years compared with 4.5 in non-Aboriginal people. Aboriginal age-standardised CF percentages were 1.4 (males) and 1.1 (females) times higher at age 25-54 years and 1.5 times higher at age 55-74 years. CONCLUSION These data suggest higher CF and, more importantly, AMI incidence contribute to the excess ischaemic heart disease mortality in Aboriginal Western Australians. The poorer cardiovascular health in Aboriginal women, particularly in younger age groups, should be investigated.

Burden of Stroke in Indigenous Western Australians A Study Using Data Linkage

Background and Purpose— Despite the disproportionate burden of cardiovascular disease among indigenous Australians, information on stroke is sparse. This article documents the incidence and burden of stroke (in disability-adjusted life years) in indigenous and non-indigenous people in Western Australia (1997–2002), a state resident to 15% of indigenous Australians comprising 3.4% of the population of Western Australia. Methods— Indigenous and non-indigenous stroke incidence and excess mortality rates were estimated from linked hospital and mortality data, with adjustment for nonadmitted events. Nonfatal burden was calculated from nonfatal incidence, duration (modeled from incidence, excess mortality, and remission), and disability weights. Stroke death counts formed the basis of fatal burden. Nonfatal and fatal burden were summed to obtain disability-adjusted life years, by indigenous status. Results— The total burden was 55 099 and 2134 disability-adjusted life years in non-indigenous and indigenous Western Australians, respectively. The indigenous to non-indigenous age-standardized stroke incidence rate ratio (≥15 years) was 2.6 in males (95% CI, 2.3–3.0) and 3.0 (95% CI, 2.6–3.5) in females, with similar rate ratios of disability-adjusted life years. The burden profile differed substantially between populations, with rate ratios being highest at younger ages. Conclusions— The differential between indigenous and non-indigenous stroke burden is considerable, highlighting the need for comprehensive intersectoral interventions to reduce indigenous stroke incidence and improve outcomes. Programs to reduce risk factors and increase access to culturally appropriate stroke services are required. The results here provide the quantitative basis for policy development and monitoring of stroke outcomes.

The quality of Indigenous identification in administrative health data in Australia: insights from studies using data linkage

BackgroundMissing or incorrect Indigenous status in health records hinders monitoring of Indigenous health indicators. Linkage of administrative data has been used to improve the ascertainment of Indigenous status. Data linkage was pioneered in Western Australia (WA) and is now being used in other Australian states. This systematic review appraises peer-reviewed Australian studies that used data linkage to elucidate the impact of under-ascertainment of Indigenous status on health indicators.MethodsA PubMed search identified eligible studies that used Australian linked data to interrogate Indigenous identification using more than one identifier and interrogated the impact of the different identifiers on estimation of Indigenous health indicators.ResultsEight papers were included, five from WA and three from New South Wales (NSW). The WA papers included a self-identified Indigenous community cohort and showed improved identification in hospital separation data after 2000. In CVD hospitalised patients (2000–05), under-identification was greater in urban residents, older people and socially more advantaged Indigenous people, with varying algorithms giving different estimates of under-count. Age-standardised myocardial infarction incidence rates (2000–2004) increased by about 10%-15% with improved identification. Under-ascertainment of Indigenous identification overestimated secular improvements in life expectancy and mortality whereas correcting infectious disease notifications resulted in lower Indigenous/ non-Indigenous rate ratios. NSW has a history of poor Indigenous identification in administrative data systems, but the NSW papers confirmed the usefulness of data linkage for improving Indigenous identification and the potential for very different estimates of Indigenous disease indicators depending upon the algorithm used for identification.ConclusionsUnder-identification of Indigenous status must be addressed in health analyses concerning Indigenous health differentials – they cannot be ignored or wished away. This problem can be substantially diminished through data linkage. Under-identification of Indigenous status impacts differently in different disease contexts, generally resulting in under-estimation of absolute and relative Indigenous health indicators, but may perversely overestimate Indigenous rates and differentials in the setting of stigma-associated conditions such as sexually-transmitted and blood-borne virus infections. Under-numeration in Census surveys also needs consideration to address the added problem of denominator undercounts.

Australia's National Bowel Cancer Screening Program: does it work for Indigenous Australians?

BackgroundDespite a lower incidence of bowel cancer overall, Indigenous Australians are more likely to be diagnosed at an advanced stage when prognosis is poor. Bowel cancer screening is an effective means of reducing incidence and mortality from bowel cancer through early identification and prompt treatment. In 2006, Australia began rolling out a population-based National Bowel Cancer Screening Program (NBCSP) using the Faecal Occult Blood Test. Initial evaluation of the program revealed substantial disparities in bowel cancer screening uptake with Indigenous Australians significantly less likely to participate in screening than the non-Indigenous population.This paper critically reviews characteristics of the program which may contribute to the discrepancy in screening uptake, and includes an analysis of organisational, structural, and socio-cultural barriers that play a part in the poorer participation of Indigenous and other disadvantaged and minority groups.MethodsA search was undertaken of peer-reviewed journal articles, government reports, and other grey literature using electronic databases and citation snowballing. Articles were critically evaluated for relevance to themes that addressed the research questions.ResultsThe NBCSP is not reaching many Indigenous Australians in the target group, with factors contributing to sub-optimal participation including how participants are selected, the way the screening kit is distributed, the nature of the test and comprehensiveness of its contents, cultural perceptions of cancer and prevailing low levels of knowledge and awareness of bowel cancer and the importance of screening.ConclusionsOur findings suggest that the population-based approach to implementing bowel cancer screening to the Australian population unintentionally excludes vulnerable minorities, particularly Indigenous and other culturally and linguistically diverse groups. This potentially contributes to exacerbating the already widening disparities in cancer outcomes that exist among Indigenous Australians. Modifications to the program are recommended to facilitate access and participation by Indigenous and other minority populations. Further research is also needed to understand the needs and social and cultural sensitivities of these groups around cancer screening and inform alternative approaches to bowel cancer screening.

High body mass index overtakes tobacco as the leading independent risk factor contributing to disease burden in Western Australia

Until recently, smoking was estimated as the leading independent risk factor contributing to the burden of disease in Australia. However, the prevalence of overweight and obesity is increasing in Australia, which now has one of the highest rates of overweight and obesity in the world. Concurrently, the prevalence of tobacco smoking has significantly decreased as a result of public health efforts. This letter presents results of a recent investigation into the contribution of selected risk factors to the burden of disease in Western Australia (WA) in 2006. The study was based on the comparative risk assessment (CRA) approach developed by the Global Burden of Disease study. This approach represents a systematic evaluation of the changes in population health, which would result from modifying the distribution of exposure to a risk factor or group of risk factors in the population. Central to CRA is the calculation of the Population Attributable Fraction (PAF), reflecting the proportion of current disease burden attributable to current and past exposure to a risk factor. The PAF is determined from the relative risks (RR) of disease in those exposed (compared to those not exposed) and the prevalence of the risk factor in the population. The RRs used in the calculation of PAFs in the WA study were consistent with those used in the Australian 2003 study, while estimates of the prevalence of high body mass and tobacco use were obtained from the WA Health and Wellbeing Surveillance System. The population burden was estimated in Disability Adjusted Life Years (DALYs). DALYs provide comparable information on the years of life lost to premature mortality and the equivalent ‘healthy’ years lost due to disability, thus reflecting both fatal and non-fatal burden. Mortality data for WA in 2006 were used to determine mortality burden. Disability burden was derived by applying the Australian 2003 baseline disease models, derived for the Australian 2003 study to more recent WA data derived from death and hospitalisation trends Table 1: The changing impact of high body mass and tobacco as independent risk factors for disease burden in various Australian studies. Study High BMI Tobacco Ranka % total DALY Ranka % total DALY Australia 19962 4 4.30% 1 9.70% WA 20003 4 3.90% 1 8.60% Australia 20031 3 7.50% 1 7.80% WA 2006 1 8.70% 2 6.50%

Aboriginal to non-Aboriginal differentials in 2-year outcomes following non-fatal first-ever acute MI persist after adjustment for comorbidity:

Background: We investigated the relationship between Aboriginality and 2-year cardiovascular disease outcomes in non-fatal first-ever myocardial infarction during 2000⊟04, with progressive adjustment of covariates, including comorbidities. Design: Historical cohort study. Methods: Person-linked hospital and mortality records were used to identify 28-day survivors of first-ever myocardial infarction in Western Australia during 2000⊟04 with 15-year lookback. The outcome measures were: (1) cardiovascular disease death; (2) recurrent admission for myocardial infarction; and (3) the composite of (1) and (2). Results: Compared with non-Aboriginal patients, Aboriginals were younger and more likely to live remotely. The proportions having 5-year histories of diabetes and chronic kidney disease were double and triple those of non-Aboriginals. When adjusting for demographic variables alone, the Aboriginal to non-Aboriginal hazard ratios for cardiovascular death or recurrent myocardial infarction were 3.6 (95% CI 2.5–5.3) in men and 4.5 (95% CI 2.8–7.3) in women. After adjustment for comorbidities, including diabetes, chronic kidney disease and heart failure, the hazard ratios decreased 36% and 47% to 2.3 (1.6–3.0) and 2.4 (1.5–4.0) in males and females, respectively. Conclusions: The high prevalence of comorbidities in Aboriginal people, including diabetes, kidney disease, heart failure, and other risk factors contribute substantially to the disparity in post-myocardial infarction outcomes in Aboriginal people, reinforcing the importance of both primary prevention and comprehensive management of chronic conditions in this population. Aboriginality remains a significant independent risk factor for disease recurrence or mortality, even after adjusting for comorbidity, suggesting the need for society-level interventions addressing social disadvantage.

Heart failure among Indigenous Australians: a systematic review

BackgroundCardiovascular diseases contribute substantially to the poor health and reduced life expectancy of Indigenous Australians. Heart failure is a common, disabling, progressive and costly complication of these disorders. The epidemiology of heart failure and the adequacy of relevant health service provision in Indigenous Australians are not well delineated.MethodsA systematic search of the electronic databases PubMed, Embase, Web of Science, Cinahl Plus, Informit and Google Scholar was undertaken in April 2012 for peer-reviewed journal articles relevant to the topic of heart failure in Indigenous Australians. Additionally, a website search was done to identify other pertinent publications, particularly government reports.ResultsThere was a paucity of relevant peer-reviewed research, and government reports dominated the results. Ten journal articles, 1 published conference abstract and 10 reports were eligible for inclusion. Indigenous Australians reportedly have higher morbidity and mortality from heart failure than their non-Indigenous counterparts (age-standardised prevalence ratio 1.7; age-standardised hospital separation ratio ≥3; crude per capita hospital expenditure ratio 1.58; age-adjusted mortality ratio >2). Despite the evident disproportionate burden of heart failure in Indigenous Australians, the accuracy of estimation from administrative data is limited by poor indigenous identification, inadequate case ascertainment and exclusion of younger subjects from mortality statistics. A recent journal article specifically documented a high prevalence of heart failure in Central Australian Aboriginal adults (5.3%), noting frequent undiagnosed disease. One study examined barriers to health service provision for Indigenous Australians in the context of heart failure.ConclusionsDespite the shortcomings of available published data, it is clear that Indigenous Australians have an excess burden of heart failure. Emerging data suggest that undiagnosed cases may be common in this population. In order to optimise management and to inform policy, high quality research on heart failure in Indigenous Australians is required to delineate accurate epidemiological indicators and to appraise health service provision.

Incidence of first heart failure hospitalisation and mortality in Aboriginal and non-Aboriginal patients in Western Australia, 2000–2009

OBJECTIVES To compare the incidence of first heart failure (HF) hospitalisation, antecedent risk factors and 1-year mortality between Aboriginal and non-Aboriginal populations in Western Australia (2000-2009). METHODS A population-based cohort aged 20-84 years comprising Aboriginal (n=1013; mean 54±14 years) and non-Aboriginal patients (n=16,366; mean 71±11 years) with first HF hospitalisation was evaluated. Age and sex-specific incidence rates and HF antecedents were compared between subpopulations. Regression models were used to examine 30-day and 1-year (in 30-day survivors) mortality. RESULTS Aboriginal patients were younger, more likely to reside in rural/remote areas (76% vs 23%) and to be women (50.6% vs 41.7%, all p<0.001). Aboriginal (versus non-Aboriginal) HF incidence rates were 11-fold higher in men and 23-fold in women aged 20-39 years, declining to about 2-fold in patients aged 70-84 years. Ischaemic and rheumatic heart diseases were more common antecedents of HF in younger (<55 years) Aboriginal versus non-Aboriginal patients (p<0.001). Hypertension, diabetes, chronic kidney disease, renal failure, chronic obstructive pulmonary disease, and a high Charlson comorbidity index (>=3) were also more prevalent in younger and older Aboriginal patients (p<0.001). Although 30-day mortality was similar in both subpopulations, Aboriginal patients aged<55 years had a 1.9 risk-adjusted hazard ratio (HR) for 1-year mortality (p=0.015). CONCLUSIONS Aboriginal people had substantially higher age and sex-specific HF incidence rate and prevalence of HF antecedents than their non-Aboriginal counterparts. HR for 1-year mortality was also significantly worse at younger ages, highlighting the urgent need for enhanced primary and secondary prevention of HF in this population.

The disability adjusted life years due to stroke in South Africa in 2008

Background South Africa is experiencing epidemiological transition, with the burden of chronic diseases increasing. Stroke is currently the second leading cause of death in South Africa; however, limited data are available on incidence, prevalence and resulting disability. Quantifying the epidemiological parameters and disease burden is important in the planning of health services. Aims To synthesize the data surrounding stroke in South Africa and calculate disability adjusted life years attributable to stroke in South Africa in 2008. Methods We undertook a systematic review to identify studies on the prevalence and mortality of stroke in South Africa. We used the DisMod program to calculate missing epidemiological parameters, in particular incidence and duration. Using these values, we calculated the burden of disease in years of life lost (YLL), years lived with disability (YLD) and disability adjusted life years (DALY). Results Data on prevalence and mortality of stroke in South Africa are scarce. We estimate there are 75 000 strokes in South Africa each year, with 25 000 of these fatal within the first month. The burden of disease due to stroke in South Africa was 564 000 DALYs. Of this, 17% is contributed by YLD (14–20% in sensitivity analysis). Conclusions This study provides information on prevalence, incidence and disease burden of stroke at the national level in South Africa. The results of this analysis will enable further work on priority setting and health service planning for primary and secondary prevention of stroke in South Africa.