Challenges and strategies for cohort retention and data collection in an indigenous population: Australian Aboriginal Birth Cohort.

BACKGROUND: Longitudinal prospective birth cohort studies are pivotal to identifying fundamental causes and determinants of disease and health over the life course. There is limited information about the challenges, retention, and collection strategies in the study of Indigenous populations. The aim is to describe the follow-up rates of an Australian Aboriginal Birth Cohort study and how they were achieved. METHODS: Participants were 686 babies enrolled between January 1987 and March 1990, born to a mother recorded in the Delivery Suite Register of the Royal Darwin Hospital (RDH) as a self-identified Aboriginal. The majority of the participants (70%) resided in Northern Territory within rural, remote and very remote Aboriginal communities that maintain traditional connections to their land and culture. The Aboriginal communities are within a sparsely populated (0.2 people/ km2) area of approximately 900,000 km² (347 sq miles), with poor communication and transport infrastructures. Follow-ups collecting biomedical and lifestyle data directly from participants in over 40 locations were conducted at 11.4 years (Wave-2) and 18.2 years (Wave-3), with Wave-4 follow-up currently underway. RESULTS: Follow-ups at 11 and 18 years of age successfully examined 86% and 72% of living participants respectively. Strategies addressing logistic, cultural and ethical challenges are documented. CONCLUSIONS: Satisfactory follow-up rates of a prospective longitudinal Indigenous birth cohort with traditional characteristics are possible while maintaining scientific rigor in a challenging setting. Approaches included flexibility, respect, and transparent communication along with the adoption of culturally sensitive behaviours. This work should inform and assist researchers undertaking or planning similar studies in Indigenous and developing populations.

Prevalence and validity of self-reported smoking in Indigenous and non-Indigenous young adults in the Australian Northern Territory.

BACKGROUND: In this study, we used data from Australia's Northern Territory to assess differences in self-reported smoking prevalence between the Indigenous and non-Indigenous populations. We also used urinary cotinine data to assess the validity of using self-reported smoking data in these populations. METHODS: The Aboriginal Birth Cohort (ABC) is a prospective study of 686 Aboriginal babies born in Darwin 1987-90. The Top End Cohort (TEC) is a study of non-Indigenous adolescents, all born in Darwin 1987-91. In both studies, participants aged between 16 and 21 years, were asked whether they smoked. Urinary cotinine measurements were made from samples taken at the same visits. RESULTS: Self-reported smoking prevalence was 68% in the ABC and 14% in the TEC. Among the self-reported non-smokers, the median cotinine levels were higher in the ABC (33 ng/ml) than in the TEC (5 ng/ml), with greater percentages of reported non-smokers in the under 50 ng/ml group in the TEC than in the ABC CONCLUSIONS: Prevalence of smoking was much higher in the ABC than in the TEC. The higher cotinine levels in ABC non-smokers may reflect an underestimated prevalence, but is also likely to reflect higher levels of passive smoking. A broader approach encompassing social, cultural and language factors with increased attention to smoking socialisation factors is required.

Birthweight and fasting glucose and insulin levels: results from the Aboriginal Birth Cohort Study.

OBJECTIVE: To examine the relationships between birthweight, current size, and fasting glucose and fasting insulin levels in Aboriginal adolescents. DESIGN, PARTICIPANTS AND SETTING: Longitudinal prospective study of a Northern Territory Aboriginal birth cohort of 686 Aboriginal babies born at the Royal Darwin Hospital between January 1987 and March 1990, and followed up between December 2006 and January 2008 in over 40 NT locations. MAIN OUTCOME MEASURES: Fasting insulin and glucose levels, adjusted for gestational age, sex and contemporary age. RESULTS: Among the 134 participants with complete data, those with fetal growth restriction (FGR) or low birthweight (LBW) at birth were not overweight at 18 2013s. In these circumstances, birthweight showed a significant positively directed association with fasting glucose levels (P = 0.002). Current weight showed a significant and positively directed association with both fasting insulin (P < 0.001) and fasting glucose levels (P = 0.001), and current height showed a significant and positively directed association with insulin levels (P = 0.006). CONCLUSIONS: Birthweight was only positively associated with fasting glucose levels, with no association with fasting insulin levels. The high-risk combination for type 2 diabetes of LBW or FGR with later overweight or obesity was rare in this adolescent Aboriginal population.

Fetal growth restriction and 18-year growth and nutritional status: Aboriginal birth cohort 1987-2007.

The main objective of the work is to compare the growth and nutritional status of Australian Aboriginal term infants born with (n = 81) and without fetal growth restriction (n = 260). A prospective birth cohort study of 341 Aboriginal babies from the Top End of the Northern Territory of Australia was recruited at birth (1987-1990) and re-examined at a mean age of 18.3 years (2006-2008) for outcome measures of growth and nutrition status. Those with growth restriction at birth were 3 cm shorter (P = 0.0026) and 9 kg lighter (P = 0.0001) with head circumferences 0.95 cm smaller (P = 0.0008) than those without growth restriction. The proportions of growth restricted participants with body mass index <18.5 kg/m(2) were significantly greater (P = 0.028), and those with BMI > 25 kg/m(2) and with fat percentage >85th percentile were significantly smaller (P = 0.012 and 0.004, respectively). In this cohort, those Aboriginal babies born smaller and lighter have remained smaller and lighter at 18 years of age. However, the highest risk of later chronic noncommunicable disease has been reported in subjects who were born small and become relatively larger in later life. The continued study of this Aboriginal birth cohort will give us an opportunity to determine if and when in later life the effects of birth weight are modified by environmental nutritional factors.

Oral health and social and emotional well-being in a birth cohort of Aboriginal Australian young adults.

BACKGROUND: Social and emotional well-being is an important component of overall health. In the Indigenous Australian context, risk indicators of poor social and emotional well-being include social determinants such as poor education, employment, income and housing as well as substance use, racial discrimination and cultural knowledge. This study sought to investigate associations between oral health-related factors and social and emotional well-being in a birth cohort of young Aboriginal adults residing in the northern region of Australia's Northern Territory. METHODS: Data were collected on five validated domains of social and emotional well-being: anxiety, resilience, depression, suicide and overall mental health. Independent variables included socio-demographics, dental health behaviour, dental disease experience, oral health-related quality of life, substance use, racial discrimination and cultural knowledge. RESULTS: After adjusting for other covariates, poor oral health-related items were associated with each of the social and emotional well-being domains. Specifically, anxiety was associated with being female, having one or more decayed teeth and racial discrimination. Resilience was associated with being male, having a job, owning a toothbrush, having one or more filled teeth and knowing a lot about Indigenous culture; while being female, having experienced dental pain in the past year, use of alcohol, use of marijuana and racial discrimination were associated with depression. Suicide was associated with being female, having experience of untreated dental decay and racial discrimination; while being female, having experience of dental disease in one or more teeth, being dissatisfied about dental appearance and racial discrimination were associated with poor mental health. CONCLUSION: The results suggest there may be value in including oral health-related initiatives when exploring the role of physical conditions on Indigenous social and emotional well-being.

Lipoprotein(a) identifies cardiovascular risk in childhood: the Australian Aboriginal Birth Cohort Study.

AIM: To describe the lipoprotein(a) (Lp(a))profile and its relationship to cardiovascular risk factors in Australian Aboriginal children. METHODS: A cross-sectional study within a longitudinal birth cohort study in the Darwin Health Region (Northern Territory, Australia). Subjects were Aboriginal children born between 1987 and 1990 who were re-examined between 1998 and 2001. Outcome measures were cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apoB, apoA1, apoA1/B ratio, anthropometric measures, cardiovascular disease (CVD) risk factors, maternal smoking and nutrition. RESULTS: At a mean age of 11.4 years, results showed that high concentrations of Lp(a) were significantly related to well-known lipid-based CVD risk factors for both boys and girls, and that only one anthropometric factor, height, was significant for girls. Non-genetic factors and maternal smoking were not found to be significant contributors to Lp(a) concentrations. CONCLUSIONS: Lp(a) should be considered as a more effective marker of CVD than anthropometric measures, and children from families with a history of premature CVD should be regularly screened for this factor.

Strong Souls: development and validation of a culturally appropriate tool for assessment of social and emotional well-being in Indigenous youth.

OBJECTIVE: The aim of the present study was to develop and validate an appropriate tool to assess the social and emotional well-being (SEWB) of Indigenous adolescents participating in the longitudinal Aboriginal Birth Cohort (ABC) Study. METHOD: A range of tools was assessed as to the suitability of each for use in the ABC Study. Two existing tools and a newly developed one called 'Strong Souls' were piloted in a representative group (n = 67). Strong Souls was selected as the most appropriate for use in the ABC Study, and was completed by 361 participants. Exploratory factor analysis was used to explore construct validity. Cronbach alpha was used to assess the reliability of the latent constructs and the tool overall. RESULTS: Factor analysis produced a 25-item, four-factor model accounting for 34.5% of the variance. This model demonstrated sound construct validity and reliability. Factor structure was consistent with the epidemiological literature, identifying constructs of anxiety, resilience, depression and suicide risk. While these align with observations in mainstream populations, different relationships between distinct factors, and differences in symptomatology were found in this population. For example, two key findings were: feelings of sadness and low mood were linked with anxiety and not depression; and the expression of anger was verified as a unique symptom of depression for Indigenous people. CONCLUSIONS: Strong Souls demonstrated validity, reliability and cultural appropriateness as a tool for screening for SEWB among Indigenous young people in the Northern Territory.

Indigenous perinatal and neonatal outcomes: a time for preventive strategies.

Pregnancy outcomes for Indigenous mothers and babies have improved, but marked disparities remain between Indigenous and non-Indigenous women. Many contributors to these disparities such as smoking, alcohol use, poor nutrition, infection, teenage pregnancy and stress are preventable or modifiable particularly if addressed prior to pregnancy. It is suggested that we expand our reproductive health research, education and care to a life course approach beginning in early adolescence.

Risk indicators for severe impaired oral health among indigenous Australian young adults.

BACKGROUND: Oral health impairment comprises three conceptual domains; pain, appearance and function. This study sought to: (1) estimate the prevalence of severe oral health impairment as assessed by a summary oral health impairment measure, including aspects of dental pain, dissatisfaction with dental appearance and difficulty eating, among a birth cohort of Indigenous Australian young adults (n = 442, age range 16-20 years); (2) compare prevalence according to demographic, socio-economic, behavioural, dental service utilisation and oral health outcome risk indicators; and (3) ascertain the independent contribution of those risk indicators to severe oral health impairment in this population. METHODS: Data were from the Aboriginal Birth Cohort (ABC) study, a prospective longitudinal investigation of Aboriginal individuals born 1987-1990 at an Australian regional hospital. Data for this analysis pertained to Wave-3 of the study only. Severe oral health impairment was defined as reported experience of toothache, poor dental appearance and food avoidance in the last 12 months. Logistic regression models were used to evaluate effects of demographic, socio-economic, behavioural, dental service utilisation and clinical oral disease indicators on severe oral health impairment. Effects were quantified as odds ratios (OR). RESULTS: The percent of participants with severe oral health impairment was 16.3 (95% CI 12.9-19.7). In the multivariate model, severe oral health impairment was associated with untreated dental decay (OR 4.0, 95% CI 1.6-9.6). In addition to that clinical indicator, greater odds of severe oral health impairment were associated with being female (OR 2.0, 95% CI 1.2-3.6), being aged 19-20 years (OR 2.1, 95% CI 1.2-3.6), soft drink consumption every day or a few days a week (OR 2.6, 95% 1.2-5.6) and non-ownership of a toothbrush (OR 1.9, 95% CI 1.1-3.4). CONCLUSIONS: Severe oral health impairment was prevalent among this population. The findings suggest that public health strategies that address prevention and treatment of dental disease, self-regulation of soft drink consumption and ownership of oral self-care devices are needed if severe oral health impairment among Indigenous Australian young adults is to be reduced.

Relationships between birthweight and biomarkers of chronic disease in childhood: Aboriginal Birth Cohort Study 1987-2001.

Reports of relationships between lower birthweight and later chronic diseases are mainly from populations with low rates of low birthweight (LBW) and growth-restricted births. A prospective study of an Australian Aboriginal birth cohort with a mean birthweight of 3050 g (SD 630), 16% LBW and 28% fetal growth restriction was used to examine the relationships between birthweight and selected biomarkers of chronic adult disease. At a mean age of 11.4 years (range 8.9-14), the mean weight was 35.7 kg (SD 11.8) and the mean height was 143.8 cm (SD 10.6). Using the Centers for Disease Control and Prevention (CDC) 2000 growth references, weight and height-for-age z-scores were -0.8 (SD 1.4) and -0.5 (SD 1.07) respectively and using World Health Organisation criteria, 19% of children were classified as underweight (weight for age Z-score <2.0). The relationships between birthweight and blood pressure (n = 475), total cholesterol (n = 461), Apolipoprotein A-1 (n = 343), Apolipoprotein B (n = 390), respiratory function tests (n = 427), kidney size determined by ultrasound (n = 446), urinary albumin/creatinine ratio (n = 420) and fasting triglycerides (n = 281), insulin (n = 272) and glucose (n = 279) were examined using regression models adjusted for sex, gestational age, current age and puberty status. In this population with high rates of fetal growth restriction at birth and an excess of under-nutrition at age 11 years we found that birthweight had a negative relationship with child blood pressure only, while current child weight was positively related to blood pressure, total cholesterol, Apolipoprotein B, respiratory function tests, kidney size, and fasting triglycerides, insulin and glucose.

The development and evaluation of a simple method of gestational age estimation.

AIMS: The aims of this study were to develop and evaluate a shorter gestational age estimation method based on the Dubowitz scoring system (DSS) that could be taught easily to untrained health-care workers. METHODS: Using the DSS, seven criteria were identified that explained 90% of the variance in gestational age estimation. Ventral suspension was excluded, skin texture was substituted for skin colour and ear bending was for ear firmness. The final six criteria comprise the short DSS (SDSS). The study population was 100 babies, 51 Caucasian, 34 Aboriginal. Birth weight ranged from 1351 to 5430 g. The gestational age range was 29.6-41.7 weeks. Three researchers (medical student 1 (MS1), medical student 2 (MS2) and a paediatrician) who were blind to other available gestational age estimations assessed babies within 72 h of birth using the DSS and SDSS. RESULTS: MS1 found the 95% limits of agreement (LOA) between SDSS and DSS to be -1.1 to 1.7 weeks. In the 27 babies who had first trimester foetal ultrasound (USS), the LOA between USS and SDSS were -1.9 to 1.4 weeks and -2.3 to 1.9 weeks, respectively. Using the SDSS, the LOA for the three researchers were within +/-2 weeks. CONCLUSION: The data presented suggest that the SDSS is approximately equivalent to the DSS in the relatively limited population studied, and within these limitations appears to be a simple alternative to the DSS. Further evaluation is needed before firm conclusions about the accuracy and clinical utility of the SDSS can be made.

Australian Aboriginal Birth Cohort study: follow-up processes at 20 years.

BACKGROUND: In 1987, a prospective study of an Australian Aboriginal Birth Cohort was established focusing on the relationships of fetal and childhood growth with the risk of chronic adult disease. However as the study is being conducted in a highly marginalized population it is also an important resource for cross-sectional descriptive and analytical studies. The aim of this paper is to describe the processes of the third follow up which was conducted 20 years after recruitment at birth. METHODS: Progressive steps in a multiphase protocol were used for tracing, with modifications for the expected rural or urban location of the participants. RESULTS: Of the original 686 cohort participants recruited 68 were untraced and 27 were known to have died. Of the 591 available for examination 122 were not examined; 11 of these were refusals and the remainder were not seen for logistical reasons relating to inclement weather, mobility of participants and single participants living in very remote locations. CONCLUSION: The high retention rate of this follow-up 20 years after birth recruitment is a testament to the development of successful multiphase protocols aimed at overcoming the challenges of tracing a cohort over a widespread remote area and also to the perseverance of the study personnel. We also interpret the high retention rate as a reflection of the good will of the wider Aboriginal community towards this study and that researchers interactions with the community were positive. The continued follow-up of this life course study now seems feasible and there are plans to trace and reexamine the cohort at age 25 years.

Large waist but low body mass index: the metabolic syndrome in Australian Aboriginal children.

OBJECTIVE: To describe the prevalence and clinical characteristics of the metabolic syndrome (MetS) in a cohort of Australian Aboriginal children. STUDY DESIGN: Body mass index (BMI), waist circumference, skin fold thickness, body fat percentage, insulin resistance, and the prevalence of MetS were evaluated in 486 children age 9 to 14 years from the Darwin Health Region, Northern Territory, Australia. RESULTS: Using an age- and sex- specific definition, 14% of the children in the cohort had MetS, 6.4% were overweight, 4.9% were obese, and 26.2% had an elevated waist circumference. The mean percentage of body fat was 30.2%. The children with MetS had higher BMI and waist z-scores, percent body fat, Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) score, and skin fold thickness compared with those without MetS (P < .001); however, >50% of those with MetS were neither overweight nor obese. Waist circumference was significantly associated with insulin resistance as measured by the HOMA-IR (P < .001). CONCLUSIONS: MetS is common in our cohort despite low rates of overweight and obesity. A tendency for central adiposity is already evident in these young children. Measurement of waist circumference may help identify Aboriginal children at high risk for MetS.

Oral health investigations of indigenous participants in remote settings: a methods paper describing the dental component of wave III of an Australian Aboriginal birth cohort study.

BACKGROUND: A prospective Aboriginal Birth Cohort (ABC) study has been underway in Australia's Northern Territory since 1987. Inclusion of oral epidemiological information in a follow-up study required flexible and novel approaches with unconventional techniques. Documenting these procedures may be of value to researchers interested in including oral health components in remotely-located studies. The objectives are to compare and describe dental data collection methods in wave III of the ABC study with a more conventional oral health investigation. METHODS: The Australian National Survey of Adult Oral Health (NSAOH) was considered the 'conventional' study. Differences between this investigation and the dental component of the ABC study were assessed in terms of ethics, location, recruitment, consent, privacy, equipment, examination, clinical data collection and replication. In the ABC study, recording of clinical data by different voice recording techniques were described and assessed for ease-of-use portability, reliability, time-efficiency and cost-effectiveness. RESULTS: Conventional investigation recruitment was by post and telephone. Participants self presented. Examinations took place in dental clinics, using customised dental chairs with standard dental lights attached. For all examinations, a dental assistant recorded dental data directly onto a laptop computer. By contrast, follow-up of ABC study participants involved a multi-phase protocol with reliance on locally-employed Indigenous advocates bringing participants to the examination point. Dental examinations occurred in settings ranging from health centre clinic rooms to improvised spaces outdoors. The dental chair was a lightweight, portable reclining camp chair and the dental light a fire-fighter's head torch with rechargeable batteries. The digital voice recorder was considered the most suitable instrument for clinical dental data collection in the ABC study in comparison with computer-based voice-recording software. CONCLUSION: Oral health examinations among indigenous populations residing in predominantly remote locations are more logistically challenging than are surveys of the general population. However, lack of resources or conventional clinical infrastructures need not compromise the collection of dental data in such studies. Instead, there is a need to be flexible and creative in establishing culturally-sensitive environments with available resources, and to consider non-conventional approaches to data gathering.

Childhood metabolic syndrome, inflammation and carotid intima-media thickness. The Aboriginal Birth Cohort Study.

BACKGROUND/OBJECTIVES: We evaluated whether atherosclerotic changes associated with MetS in Australian Aboriginals are reversible in childhood. In addition, we investigated whether heightened inflammation is mediating the adverse effects of MetS. METHODS: The study cohort comprised of 351 children from the Aboriginal Birth Cohort Study (a longitudinal study based in the Northern Territory of Australia) aged 9-13 years at baseline examination who were followed up 6 years later. MetS was defined by at least three of the following parameters within the extreme sex- and age-specific quartile: highest quartile for waist circumference, blood pressure, triglycerides, and glucose, and lowest quartile for HDL-cholesterol. Carotid intima-media thickness (IMT) and C-reactive protein (CRP) were assessed at follow-up. RESULTS: Individuals with MetS at baseline or follow-up had increased carotid IMT at follow-up (mean ± SEM 539 ± 3 vs. 561 ± 8 µm, P=0.007; and 537 ± 3 vs. 567 ± 8 µm, P<0.0001 respectively). In combined analyses from baseline and follow-up studies, those individuals with MetS only at baseline had partially improved vascular status; their IMT was not significantly increased compared to those without MetS at both time-points (534 ± 3 vs. 550 ± 10 µm, P=0.09). At the follow-up examination, MetS status was associated with increased IMT levels only among individuals with CRP levels above the median (≥ 2.1mg/l) (536 ± 5 vs. 573 ± 9 µm, P<0.0001, P for interaction 0.01). CONCLUSIONS: MetS in childhood is associated with subclinical atherosclerosis in an Australian Aboriginal population and the effects appear to be mediated by increased inflammation. The extent of atherosclerosis was partially reduced if metabolic status improved during the follow-up.

Pathways between birth weight and later body size in predicting blood pressure: Australian Aboriginal Cohort Study 1987-2007.

BACKGROUND: Although a large number of previous studies suggest an association between birth weight and later blood pressure, others do not. Controversy surrounds the relative importance of these associations, in particular in relation to more modifiable factors in later life and whether the association would be seen in a, relatively disadvantaged, Indigenous population. The aim of this study, within the Aboriginal Birth Cohort study, was to examine the relative contributions and mediating pathways of birth weight, and later growth and lifestyle factors to variation in blood pressure at age 16-20 years. METHODS: Detailed information was collected prospectively, including maternal smoking, birth weight, childhood BMI. At age 16-20 years, 451 underwent clinical examination, including the measurement of diastolic and systolic blood pressures. These data were analyzed using linear regression and path analyses, incorporating adjustment for potential confounders. RESULTS: Increased BMI at age 18 years was significantly associated with both increasing systolic and diastolic blood pressures. BMI had the highest relative importance and mediated the effects from earlier in life, including birth weight. Being female and living in remote residence were also independently associated with a reduction in systolic blood pressure. CONCLUSION: Blood pressure in this cohort is primarily influenced by contemporaneous BMI, which in this population at this age is generally lower than that seen in non-Indigenous populations in developed countries. However, other factors, including birth weight, do appear to play a role that is mediated through later BMI.

In an Aboriginal birth cohort, only child size and not birth size, predicts insulin and glucose concentrations in childhood.

The objectives were to describe cross-sectional growth in 279 Australian Aboriginal children aged 8-14 years in order to test the hypothesis that birth size interacts with child size to predict glucose and insulin metabolism. Cross-sectional growth outcomes were described using standard deviation scores or z-scores for height for age (HAZ) and weight for age (WAZ) calculated from CDC 2000 reference values in Epi Info 2000. Interrelationships were examined using standard regression models with current height and weight and birth weight, ponderal index and birth weight below the 10th percentile for gestational age. All models were adjusted for gestational age, gender and chronological age. Growth outcomes were poor with negative mean z scores for height and weight. Children with a birth weight <10th percentile for gestational age were significantly smaller and lighter than those with a birth >/= 10th percentile for gestational age, indicating post-natal catch-up growth of small babies was unlikely. After adjustment for childhood size, there was no relationship between any birth measures and fasting glucose or insulin concentrations. Current child height and weight had positive relationships with both fasting insulin and glucose concentrations with a greater proportional change for insulin. For every increment of 1cm in height or 1 kg in weight, insulin concentrations rose 2% whereas glucose increased by only 0.2%. In this indigenous Australian cohort with poor post-natal growth, only current child size is related to measures of glucose and insulin metabolism.

An Australian Aboriginal birth cohort: a unique resource for a life course study of an Indigenous population. A study protocol.

BACKGROUND: The global rise of Type 2 diabetes and its complications has drawn attention to the burden of non-communicable diseases on populations undergoing epidemiological transition. The life course approach of a birth cohort has the potential to increase our understanding of the development of these chronic diseases. In 1987 we sought to establish an Australian Indigenous birth cohort to be used as a resource for descriptive and analytical studies with particular attention on non-communicable diseases. The focus of this report is the methodology of recruiting and following-up an Aboriginal birth cohort of mobile subjects belonging to diverse cultural and language groups living in a large sparsely populated area in the Top End of the Northern Territory of Australia. METHODS: A prospective longitudinal study of Aboriginal singletons born at the Royal Darwin Hospital 1987-1990, with second wave cross-sectional follow-up examination of subjects 1998-2001 in over 70 different locations. A multiphase protocol was used to locate and collect data on 686 subjects with different approaches for urban and rural children. Manual chart audits, faxes to remote communities, death registries and a full time subject locator with past experience of Aboriginal communities were all used. DISCUSSION: The successful recruitment of 686 Indigenous subjects followed up 14 years later with vital status determined for 95% of subjects and examination of 86% shows an Indigenous birth cohort can be established in an environment with geographic, cultural and climatic challenges. The high rates of recruitment and follow up indicate there were effective strategies of follow-up in a supportive population.