Objectives

Lifetime risk of coronary heart disease (CHD) is an important yardstick by which policy makers, clinicians and the general public can assess and promote the awareness and prevention of CHD. The lifetime risk in Aboriginal people is not known. Using a cohort with up to 20 years of follow-up, we estimated the lifetime risk of CHD in Aboriginal people.

Design

A cohort study.

Setting

A remote Aboriginal region.

Participants

1115 Aboriginal people from one remote tribal group who were free from CHD at baseline were followed for up to 20 years.

Main outcome measures

During the follow-up period, new CHD incident cases were identified through hospital and death records. We estimated the lifetime risks of CHD with and without adjusting for the presence of competing risk of death from non-CHD causes.

Results

Participants were followed up for 17 126 person-years, during which 185 developed CHD and 144 died from non-CHD causes. The average age at which the first CHD event occurred was 48 years for men and 49 years for women. The risk of developing CHD increased with age until 60 years and then decreased with age. Lifetime cumulative risk without adjusting for competing risk was 70.7% for men and 63.8% for women. Adjusting for the presence of competing risk of death from non-CHD causes, the lifetime risk of CHD was 52.6% for men and 49.2% for women.

Conclusions

Lifetime risk of CHD is as high as one in two in both Aboriginal men and women. The average age of having first CHD events was under 50 years, much younger than that reported in non-Aboriginal populations. Our data provide useful knowledge for health education, screening and prevention of CHD in Aboriginal people.

Background

Chronic kidney disease (CKD) is recognized as a major public health problem in Australia with significant mortality, morbidity and economic burden. However, there is no comprehensive surveillance programme to collect, collate and analyse data on CKD in a systematic way.

Methods

We describe an initiative called CKD Queensland (CKD.QLD), which was established in 2009 to address this deficiency, and outline the processes and progress made to date. The foundation is a CKD Registry of all CKD patients attending public health renal services in Queensland, and patient recruitment and data capture have started.

Results

We have established through early work of CKD.QLD that there are over 11 500 CKD patients attending public renal services in Queensland, and these are the target population for our registry. Progress so far includes conducting two CKD clinic site surveys, consenting over 3000 patients into the registry and initiation of baseline data analysis of the first 600 patients enrolled at the Royal Brisbane and Women's Hospital (RBWH) site. In addition, research studies in dietary intake and CKD outcomes and in models of care in CKD patient management are underway.

Conclusions

Through the CKD Registry, we will define the distribution of CKD patients referred to renal practices in the public system in Queensland by region, remoteness, age, gender, ethnicity and socioeconomic status. We will define the clinical characteristics of those patients, and the CKD associations, stages, co-morbidities and current management. We will follow the course and outcomes in individuals over time, as well as group trends over time. Through our activities and outcomes, we are aiming to provide a nidus for other states in Australia to join in a national CKD registry and network.

Background. Glomerulomegaly, the abnormal enlargement of glomeruli, has been related to an increased risk of glomerulosclerosis, but the degree of enlargement that constitutes glomerulomegaly has not been defined.

Methods. The principal stereological methods for estimating glomerular volume are [1] the disector/Cavalieri method that is considered the ‘gold standard’ for measuring individual glomerular volume (IVglom) and [2] the disector/fractionator technique that estimates average glomerular volume (Vglom) together with total glomerular number (Nglom) for the entire kidney. The two methods produce different estimates with Vglom consistently exceeding IVglom. This study compares glomerular volumes obtained by the two methods in autopsy kidneys of 39 African American and 34 US white adult males, and correlates the values with Nglom, body mass index (BMI), hypertension, glomerulosclerosis and race, factors known or thought to influence glomerular volume.

Results. For the smallest glomeruli, Vglom was 25% larger than IVglom with the difference increasing to over 50% for kidneys with the largest glomeruli. Both Vglom and IVglom showed significant inverse correlations with Nglom and significant direct correlations with BMI and hypertension. African Americans had larger IVglom and Vglom than whites, but only IVglom was significant. The 90th percentile for IVglom was 6.81 μm3 × 106 and 13.10 μm3 × 106 for Vglom, but larger glomerular size did not separate hypertensive from non-hypertensive subjects nor did it show any significant relationship to glomerulosclerosis. While Vglom overestimated glomerular size compared with IVglom, both measurements demonstrated similar relationships to factors influencing glomerular volume.

Conclusions. With neither method could glomerulomegaly, the abnormal enlargement of glomerular size predisposing to glomerulosclerosis, be determined.

Background. Low nephron number is determined in utero and is a proposed risk for essential hypertension. Glomerular volume is inversely correlated with nephron number, and genetic and environmental factors that determine nephron number are thought to determine glomerular volume. This study compared total glomerular (nephron) number (Nglom), mean glomerular volume (Vglom) and kidney weight in two geographically separated black populations with significant common genetic ancestry.

Methods. Unbiased stereology was used to determine Nglom and Vglom in kidneys collected at coronial autopsy in an age- and sex-matched sample of 39 adult Africans from Dakar in Senegal, West Africa and 39 African Americans from Mississippi in the USA.

Results. African Americans were taller and heavier than their Senegalese counterparts. Nglom was remarkably similar—with a geometric mean of 937 967 in Senegalese and 904 412 in African Americans (P = 0.62). Vglom was correlated inversely with Nglom and directly with body surface area in both groups, but Vglom was 54% greater in African Americans than in Senegalese Africans [8.30 ± 2.92 (SD) and 5.38 ± 1.25  μm3 × 106, respectively] and remained significantly larger (38%) after adjustment for body size. Vglom increased with age in African Americans, but not in the Senegalese. Kidney weight was larger in African Americans (P < 0.0001), but kidney-to-body weight ratio was not different between groups.

Conclusions. Despite similar nephron numbers, a common genetic constitution, and even in relation to current body size, African Americans have larger Vglom than Senegalese subjects. This may mark exposure to environmental stressors or hereditary traits concentrated in the population's relocation to North America.

Background

Diabetes is an important contributor to the health inequity between Aboriginal and non-Aboriginal Australians. This study aims to estimate incidence rates of diabetes and to assess its associations with impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) among Aboriginal participants in a remote community.

Methods

Six hundred and eighty six (686) Aboriginal Australians aged 20 to 74 years free from diabetes at baseline were followed for a median of 11 years. During the follow-up period, new diabetes cases were identified through hospital records. Cox proportional hazards models were used to assess relationships of the incidence rates of diabetes with IFG, IGT and body mass index (BMI).

Results

One hundred and twenty four (124) new diabetes cases were diagnosed during the follow up period. Incidence rates increased with increasing age, from 2.2 per 1000 person-years for those younger than 25 years to 39.9 per 1000 person-years for those 45-54 years. By age of 60 years, cumulative incidence rates were 49% for Aboriginal men and 70% for Aboriginal women. The rate ratio for developing diabetes in the presence of either IFG or IGT at baseline was 2.2 (95% CI: 1.5, 3.3), adjusting for age, sex and BMI. Rate ratios for developing diabetes were 2.2 (95% CI: 1.4, 3.5) for people who were overweight and 4.7 (95% CI: 3.0, 7.4) for people who were obese at baseline, with adjustment of age, sex and the presence of IFG/IGT.

Conclusions

Diabetes incidence rates are high in Aboriginal people. The lifetime risk of developing diabetes among Aboriginal men is one in two, and among Aboriginal women is two in three. Baseline IFG, IGT and obesity are important predictors of diabetes.

Background. Glomerular hypertrophy has been described in several populations at high risk of chronic kidney disease. Total nephron (and thereby glomerular) number (Nglom) varies widely in normal adult human kidneys and is generally inversely correlated with mean glomerular volume (Vglom). However, little is known about the range of individual glomerular volumes (IVglom) within single human kidneys and the association with Nglom. The aim of the present study was to estimate IVglom in Caucasian and African Americans and identify any associations between heterogeneity in IVglom and nephron number.

Methods. Using unbiased stereological techniques, IVglom was determined for 30 glomeruli in each of 24 adult male kidneys from Jackson, MS, USA (12 Caucasian and 12 African American). Half of each group had ‘high’ Nglom (>1.2 million nephrons per kidney) and the other half had ‘low’ Nglom (<600 000).

Results. Caucasians with high Nglom had a relatively homogeneous distribution of IVglom as well as a relatively low mean value, while those with low Nglom had much greater heterogeneity of IVglom, as well as a larger IVglom (P < 0.0001) compared with those with high Nglom. This disparity was not apparent in African Americans, however, where subjects with both high and low Nglom showed substantial heterogeneity in IVglom and larger mean values (P = 0.95).

Conclusions. High Nglom appeared to protect against glomerular enlargement and volume heterogeneity in Caucasians. However, substantial variation in IVglom and net enlargement in glomerular size in African Americans with high nephron numbers suggest that additional forces, independent of low Nglom, are driving glomerular enlargement and heterogeneity.

Background. Glomerulomegaly has been associated with an increased risk of renal disease. Few reports have investigated the heterogeneity of glomerular size within kidneys and associated risk factors. This study measured the individual glomerular volume (IGV) of 720 non-sclerotic glomeruli in kidneys of adult West African males, and investigated associations of IGV with age, total glomerular (nephron) number and body surface area (BSA).

Methods. IGVs were determined in the kidneys of 24 Senegalese males from two age groups (12 subjects aged 20– 30 years and 12 subjects aged 50–70 years). Subjects were randomly chosen at autopsies performed at Le Dantec Hospital in Dakar. Volumes of 30 glomeruli per subject were determined using the disector/Cavalieri stereological method.

Results. IGVs ranged from 1.31 × 106 μm3 to 12.40 × 106 μm3 (a 9.4-fold variation). IGV varied up to 5.3-fold within single kidneys. The trimmed range of IGV within subjects (10th to 90th percentile of IGV) was directly correlated with median glomerular size. The mean and standard deviation (SD) of IGV did not differ significantly between age groups or between subjects with higher (≥1.78 m2) and lower BSA (<1.78 m2). In older subjects the SD of IGV was significantly and directly correlated with BSA. Kidneys with less than 1 million nephrons had significantly larger mean IGV than kidneys with more than 1 million nephrons, and the trimmed range of IGVs within subjects was inversely correlated with total glomerular number.

Conclusion. There was a considerable variation in IGV within kidneys of Senegalese males at autopsy. The heterogeneity of IGV was increased in association with low nephron number and increased BSA, with more pronounced effects in older subjects.

Background. Low glomerular number and large glomerular volume are hypothesized to be risk factors for hypertensive renal disease in adult life. Reports of human glomerular number are based on studies from developed nations and have found single kidney mean values of ∼900 000 per kidney with a roughly 8-fold range matched by a similar range in glomerular volume. Glomerular number and volume have never been investigated in people from a developing country.

Methods. This study analysed the pathology of 81 autopsy kidneys from Dakar, Senegal, and determined total glomerular number and mean glomerular volume in 28 of these kidneys using the physical disector/fractionator method.

Results. Total glomerular number ranged 2.6-fold from 536 171 to 1 394 010, with a mean of 925 485 nephrons. The mean glomerular volume was 5.74 μm3 × 106 with a 2.5-fold variation that was strongly and inversely correlated with total glomerular number. Glomerular number was inversely correlated with age, and age-associated increases in arteriosclerosis, cortical fibrosis and glomerulosclerosis were observed. Arteriolar nephrosclerosis was observed in 34% of adults. Mean glomerular number in this Dakar population was similar to that previously reported for people from developed nations, while the range of glomerular number and mean glomerular volume was much narrower.

Conclusions. The frequency of arteriolar nephrosclerosis in these Senegalese adults was high (34%), suggesting that hypertensive kidney disease could contribute to a large burden of future chronic kidney disease in this population. Unusually low glomerular number or large glomerular volume do not appear to provide a basis for this potential burden of kidney disease.

This paper describes the process of establishing as automated system for abstraction of computerized healthcare administrative data from a hospital or clinical database (HIS) into a new data structure which has been tailored for research interests. This process involves careful study of the HIS holdings and data collection procedures, means of categorizing and organizing data, and techniques for standardized maintenance of the new database over many years. Benefits of creating and using the new database for specific projects and its limitations are also discussed.

The rates of end-stage renal disease are much increased in American Indians, but no longitudinal study of its rates and causes has been undertaken in any tribe. This 15-year study of rates and causes of treated end-stage renal disease in the Navajo, the largest Indian tribe, supplies an important model on which to base projections and plan interventions. Treated end-stage renal disease in Navajos has increased to an age-adjusted incidence 4 times that in whites in the United States. Diabetic nephropathy accounted for 50% of all new cases in 1985, with an incidence 9.6 times that in US whites, and was due entirely to type II disease. Glomerulonephritis caused end-stage renal disease in Navajos at a rate at least 1.8 times that in US whites and afflicted a much younger population. The predominant form was mesangial proliferative glomerulonephritis associated with an immune complex deposition. Renal disease of unknown etiology, which probably includes much silent glomerulonephritis, accounted for 20% of all new cases. The aggregate Navajo population with end-stage renal disease was 9 years younger than its US counterpart.

These observations reflect the genesis of the epidemic of diabetic nephropathy afflicting many tribes. Urgent measures are needed to contain this. In addition, the etiology and control of mesangiopathic, immune-complex glomerulonephritis of unusual severity, a previously unrecognized problem, need to be addressed.