Aboriginal Birth Cohort Study Research Articles

Association between perinatal and early life exposures and lung function in Australian Indigenous young adults: The Aboriginal Birth Cohort study.

Despite the high burden of respiratory disease amongst Indigenous populations, prevalence data on spirometric deficits and its determinants are limited. We estimated the prevalence of abnormal spirometry in young Indigenous adults and determined its relationship with perinatal and early life factors. We used prospectively collected data from the Australian Aboriginal Birth Cohort, a birth cohort of 686 Indigenous Australian singletons. We calculated the proportion with abnormal spirometry (z-score <-1.64) and FEV1 below the population mean (FEV1 % predicted 0 to -2SD) measured in young adulthood. We evaluated the association between perinatal and early life exposures with spirometry indices using linear regression. Fifty-nine people (39.9%, 95%CI 31.9, 48.2) had abnormal spirometry; 72 (49.3%, 95%CI 40.9, 57.7) had a FEV1 below the population mean. Pre-school hospitalisations for respiratory infections, younger maternal age, being overweight in early childhood and being born remotely were associated with reduced FEV1 and FVC (absolute, %predicted and z-score). The association between maternal age and FEV1 and FVC were stronger in women, as was hospitalization for respiratory infections before age 5. Being born remotely had a stronger association with reduced FEV1 and FVC in men. Participants born in a remote community were over 6 times more likely to have a FEV1 below the population mean (odds ratio [OR] 6.30, 95%CI 1.93, 20.59). Young Indigenous adults have a high prevalence of impaired lung function associated with several perinatal and early life factors, some of which are modifiable with feasible interventions.

Psychological Network of Stress, Coping and Social Support in an Aboriginal Population.

Over the past decades, increasing research interest has been directed towards the psychosocial factors that impact Aboriginal health, including stress, coping and social support. However, there has been no study that examined whether the behaviours, cognitions and emotions related to stress, coping and social support constitute a psychological network in an Aboriginal population and that examined its properties. To address this gap, the current study employed a new methodology, network psychometrics, to evaluate stress, coping and social support in an Aboriginal Australian population. This study conducted a secondary analysis of the South Australian Aboriginal Birth Cohort (SAABC) study, a randomised controlled trial in South Australia, which included 367 pregnant Aboriginal women at study baseline. The Gaussian Graphical Model was estimated with least absolute shrinkage and selection operator (LASSO). Node centrality was evaluated with eigencentrality, strength and bridge centrality. Network communities were investigated with the walktrap algorithm. The findings indicated that stress, coping and social support constituted a connected psychological network in an Aboriginal population. Furthermore, at the centre of the network were the troubles experienced by the Aboriginal pregnant women, bridging their perceptions of stress and coping and constituting a potential target for future interventions.

Djaalinj Waakinj (listening talking): Rationale, cultural governance, methods, population characteristics – an urban Aboriginal birth cohort study of otitis media

ABSTRACT The majority of Australian Aboriginal and Torres Strait Islander (hereafter referred to as “Aboriginal”) people live in urban centres. Otitis media (OM) occurs at a younger age, prevalence is higher and hearing loss and other serious complications are more common in Aboriginal than non-Aboriginal children. Despite this, data on the burden of OM and hearing loss in urban Aboriginal children are limited. This project was initiated following a request from urban Aboriginal people who felt the focus on more remote communities often meant urban communities were forgotten. This paper describes the development of an urban Aboriginal birth cohort study of OM that is culturally secure, outlines the process of community consultation and establishment of an Aboriginal Community Advisory Group to provide cultural governance, and presents preliminary results. Djaalinj Waakinj is an ongoing study being conducted in Perth, Western Australia, on Noongar Boodja (country). Aboriginal researchers visit people’s homes to collect sociodemographic and environmental data at enrolment of babies aged <3 months; otoscopy and tympanometry are conducted by an Aboriginal research assistant or a nurse at ages 2–4, 6–8 and 12–18 months, and full audiological assessment conducted at 9–12 months. To date, 125 participants have been enrolled; 39% of 71 children aged 2–4 months and 52% of 44 children aged 6–8 months had evidence of OM. To our knowledge, this is the first prospective cohort study aiming to determine the prevalence and risk factors associated with OM in Aboriginal infants residing in an urban area.

Socioeconomic status, remoteness and tracking of nutritional status from childhood to adulthood in an Australian Aboriginal Birth Cohort: the ABC study

ObjectivesTo determine prevalences of underweight and overweight as well as low and high waist-to-height ratio (WHtR) in three prospective follow-ups and to explore tracking of these measures of nutritional status...

The Australian Aboriginal Birth Cohort study: socio‐economic status at birth and cardiovascular risk factors to 25 years of age

To determine whether socio-economic status at birth is associated with differences in risk factors for cardiovascular disease - body mass index (BMI), blood pressure, blood lipid levels - during the first 25 years of life. Analysis of prospectively collected data. 570 of 686 children born to Aboriginal mothers at the Royal Darwin Hospital during 1987-1990 and recruited for the Aboriginal Birth Cohort Study in the Northern Territory. Participants resided in 46 urban and remote communities across the NT. The analysed data were collected at three follow-ups: Wave 2 in 1998-2001 (570 participants; mean age, 11 years), Wave 3 in 2006-2008 (442 participants; mean age, 18 years), and Wave 4 in 2014-2016 (423 participants; mean age, 25 years). Cardiovascular disease risk factors by study wave and three socio-economic measures at the time of birth: area-level Indigenous Relative Socioeconomic Outcomes (IRSEO) index score and location (urban, remote) of residence, and parity of mother. Area-level IRSEO of residence at birth influenced BMI (P<0.001), systolic blood pressure (P=0.024), LDL-cholesterol (P=0.010), and HDL-cholesterol levels (P<0.001). Remoteness of residence at birth influenced BMI (P<0.001), HDL-cholesterol (P<0.001), and triglyceride levels (P=0.043). Mother's parity at birth influenced BMI (P=0.039). Our longitudinal life course analyses indicate that area-level socio-economic factors at birth influence the prevalence of major cardiovascular disease risk factors among Indigenous Australians during childhood and early adulthood.

Association of anthropometric measures and cardiovascular risk factors in children and adolescents: Findings from the Aboriginal Birth Cohort study.

This study examined the association of anthropometric measures including height, leg length, trunk length and body mass index (BMI) at 11 and 18 years with systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol, low-density lipoprotein cholesterol (LDL-c) and high-density lipoprotein cholesterol (HDL-c) at 11 and 18 years. We analysed data from 661 participants from the Aboriginal Birth Cohort study–a longitudinal study based in the Northern Territory, Australia. Associations between anthropometric measures and cardiovascular risk factors were investigated in linear regression analyses adjusted for confounding, with imputation for missing data. In adjusted analyses, increasing leg length [males: 0.47mmHg/cm (0.23, 0.72); females: 0.50mmHg/cm (0.18, 0.83)], trunk length [males: 0.50mmHg/cm (0.28, 0.73); females: 0.57mmHg/cm (0.33, 0.81)] and height [males: 0.32mmHg/cm (0.16, 0.48); females: 0.32mmHg/cm (0.12, 0.52)] at 11 years was associated with higher SBP at 11 years. When these exposures were measured at 18 years the effect on SBP at 18 years had attenuated, and only increased trunk length was associated with higher SBP at 18 years for both sexes [males: 0.46mmHg/cm (0.05, 0.87); females: 0.69mmHg/cm (0.30, 1.08)]. We observed little association between height, leg length and trunk length and DBP, total cholesterol, LDL-c and HDL-c. Increased BMI was associated with elevated SBP and DBP at 11 and 18 years. Our findings suggest that height, leg length, and trunk length measured at 11 and 18 years was generally not associated with cardiovascular risk factors at 11 and 18 years. However, greater childhood BMI was associated with higher blood pressure and this association persisted into adolescence. This study contributes to the limited body of evidence on the association between measures of early anthropometry and cardiovascular risk among the Australian Aboriginal population.

Early life determinants of cardiovascular health in adulthood. The Australian Aboriginal Birth Cohort study

BackgroundIn 2010, The American Heart Association (AHA) set seven impact goals for ideal cardiovascular health (CVH): ideal blood pressure (BP), glucose, cholesterol levels and body mass index (BMI), physical activity on recommended levels, non-smoking and a healthy diet. We explored the prevalence of ideal CVH and the relationship between early life determinants and later CVH in an Aboriginal Birth Cohort in Australia. MethodsThe sample comprised 686 Aboriginal babies born in Darwin between 1987 and 1990. At birth, birthweight was measured and data was gathered about the families. A follow-up was conducted in adulthood. Prevalences of CVH metrics were assessed and each participant received an AHA score between 0 and 7. The relationship between socioeconomic factors at birth and later CVH was analysed. ResultsIdeal CVH was rare. Females had higher levels of ideal blood pressure (OR 5.87, P < 0.0001) and lower levels of ideal physical activity (OR 0.19, P < 0.0001). Low areal disadvantage was inversely associated with ideal levels of physical activity (OR 0.13, P = 0.04) and ideal BP (OR 0.06, P = 0.04). Participants living in urban environments had lower levels of ideal BP (OR 0.11, P = 0.03). Living in large households was inversely associated with non-smoking (OR 0.22, P = 0.02). High maternal BMI was inversely associated with ideal cholesterol (OR 0.13, P = 0.004) and ideal BP (OR 0.20, P = 0.04). ConclusionsSeveral early life factors affect later CVH in this cohort. These factors could be of significance in reducing the gap in cardiovascular mortality and morbidity between the Aboriginal and the non-Aboriginal populations in Australia.

Sub-optimal protection against past hepatitis B virus infection where subtype mismatch exists between vaccine and circulating viral genotype in northern Australia

BackgroundIn Australia’s Northern Territory, the hepatitis B virus (HBV) subgenotype A2 (subtype adw2) vaccine was introduced in 1988 for Indigenous infants. Subsequently, the circulating viral genotype has been identified as subgenotype C4 (subtype ayw3). We assessed HBV vaccine effectiveness (VE) in light of this subtype mismatch. MethodsParticipants of the Aboriginal Birth Cohort (ABC) study were recruited at birth (1987–1990), with HBV serology obtained at follow-up waves 3 (2005–2007) and 4 (2013–2015). Participants were immune if HBV surface antibody levels exceeded 10 IU/L. We determined the VE against any HBV infection (anti-HBc+) and against chronic infection (HBsAg+ or HBV DNA+), comparing non-vaccinated participants with those fulfilling United States Centers for Disease Control and Prevention (CDC) criteria for full HBV immunisation. ResultsOf 686 participants in the ABC study, we obtained HBV serology from 388 at wave 4. 181 participants were immune to HBV and 97 had evidence of any infection. Seven participants were chronically infected, of whom five had received three vaccine doses, and anti-HBc seroconversion had occurred subsequent to the three vaccine doses for two of these seven participants. Comparing the 107 participants who had been vaccinated in accordance with CDC recommendations and 127 who had not been vaccinated, VE against any infection was 67% (95%CI, 43–104%). The odds of being anti-HBc+ was 87% lower in participants raised in urban settings compared to those born into families from remote areas (OR, 0.1; 95%CI, 0.03–0.4). ConclusionsIn a setting where there exists a subtype mismatch between vaccine and circulating genotype, the vaccine was largely effective in preventing chronic infection but sub-optimal against any infection. The implications of a high prevalence of anti-HBc seropositivity in this population are unclear and require further study. The fact that anti-HBc seropositivity was strongly associated with remote dwelling suggests ongoing viral exposure in remote settings.

Cohort Profile: The Australian Aboriginal Birth Cohort (ABC) study.

Cohort Profile: The Australian Aboriginal Birth Cohort (ABC) study.

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

Background/objectivesWe 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. MethodsThe study cohort comprised of 351 children from the Aboriginal Birth Cohort Study (a longitudinal study based in the Northern Territory of Australia) aged 9–13years at baseline examination who were followed up 6years 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. ResultsIndividuals with MetS at baseline or follow-up had increased carotid IMT at follow-up (mean±SEM 539±3 vs. 561±8μm, P=0.007; and 537±3 vs. 567±8μm, 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±10μm, 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±9μm, P<0.0001, P for interaction 0.01). ConclusionsMetS 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.

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. 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. 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. 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.

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

BackgroundLongitudinal 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.MethodsParticipants 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 (347sq 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.ResultsFollow-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.ConclusionsSatisfactory 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.

Birth weight and cognitive function in early adulthood: the Australian Aboriginal birth cohort study.

It has been suggested that in addition to genetic factors, fetal and post-natal growth influence cognition in early adulthood. However, most studies have been in developed populations, so it is unclear if the same findings would be seen in other, less developed, settings, and have used testing tools not applicable to an Australia Aboriginal population. This study investigated the relationships between cognitive function in early adulthood and birth weight and contemporary height. Simple reaction time (SRT), choice reaction time (CRT) and working memory (WM) were assessed using the CogState battery. A significant association was seen between birth weight and SRT in early adulthood, but not with the other two cognitive measures. Urban dwellers had significantly shorter SRT and CRT than their remote counterparts. Contemporary body mass index and maternal age were associated with CRT. Only fetal growth restriction was associated with WM, with greater WM in those with restricted growth. No associations were seen with contemporary height. These results suggest that fetal growth may be more important than the factors influencing post-natal growth in terms of cognition in early adulthood in this population, but that the associations may be inconsistent between cognitive outcomes. Further research is required to identify whether similar associations are seen in other, similar, populations and to assess why differences in cognitive outcome measures are seen.

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.

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

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

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

To examine the relationships between birthweight, current size, and fasting glucose and fasting insulin levels in Aboriginal adolescents. 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. Fasting insulin and glucose levels, adjusted for gestational age, sex and contemporary age. 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). 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.

Aboriginal birth cohort (ABC): a prospective cohort study of early life determinants of adiposity and associated risk factors among Aboriginal people in Canada.

BackgroundAboriginal people living in Canada have a high prevalence of obesity, type 2 diabetes, and cardiovascular disease (CVD). To better understand the pre and postnatal influences on the development of adiposity and related cardio-metabolic factors in adult Aboriginal people, we will recruit and follow prospectively Aboriginal pregnant mothers and their children – the Aboriginal Birth Cohort (ABC) study.Methods/designWe aim to recruit 300 Aboriginal pregnant mothers and their newborns from the Six Nations Reserve, and follow them prospectively to age 3 years. Key details of environment and health including maternal nutrition, glucose tolerance, physical activity, and weight gain will be collected. At birth, cord blood and placenta samples will be collected, as well as newborn anthropometric measurements. Mothers and offspring will be followed annually with serial measurements of diet and physical activity, growth trajectory, and adiposity.DiscussionThere is an urgent need to understand maternal and child factors that underlie the early development of adiposity and type 2 diabetes in Aboriginal people. The information generated from this cohort will assist the Six Nations community in developing interventions to prevent early adiposity in Aboriginal children.

Associations between oral health and height in an indigenous Australian birth cohort.

Evidence suggests that taller individuals have better health than their shorter counterparts. This study aimed to test the hypothesis that shorter participants in wave-3 of the Aboriginal Birth Cohort (ABC) study, a prospective longitudinal investigation of Indigenous Australian individuals born 1987-1990 at an Australian regional hospital, would have more caries and periodontal disease experience than their taller counterparts. Data were collected through oral clinical examinations, anthropometric measures and self-report questionnaires. The outcome variables were participants' caries (mean DMFT) and periodontal disease experience (moderate or severe periodontal disease as defined by the Centre for Disease Control), with height as an explanatory variable. Antecedent anthropometric, socio-demographic, sugar consumption frequency, dental behaviour and substance use variables were used as possible confounders. Linear regression was used in the analysis of caries experience, while adjusted prevalence ratios were used for prevalence of moderate or severe periodontal disease. Higher DMFT was found among participants in the shortest tertile (B=1.02, 95% CI=0.02-2.02) and those who consumed sweets every day or a few days a week (B=1.08, 95% CI=0.11-2.05), while lower DMFT was found among those owning a toothbrush (B=0.80, 95% CI=-0.22-1.82). Periodontal disease was positively associated with the shortest tertile (adjusted PR=1.39, 95% CI=0.96-1.82) and negatively associated with toothbrush ownership (adjusted PR=0.50, 95% CI=0.34-0.66). The hypothesis that shorter participants in wave-3 of the ABC study would have higher levels of caries and periodontal disease was confirmed.

Associations between area‐level disadvantage and DMFT among a birth cohort of Indigenous Australians

Individual-level factors influence DMFT, but little is known about the influence of community environment. This study examined associations between community-level influences and DMFT among a birth cohort of Indigenous Australians aged 16-20 years. Data were collected as part of Wave 3 of the Aboriginal Birth Cohort study. Fifteen community areas were established and the sample comprised 442 individuals. The outcome variable was mean DMFT with explanatory variables including diet and community disadvantage (access to services, infrastructure and communications). Data were analysed using multilevel regression modelling. In a null model, 13.8% of the total variance in mean DMFT was between community areas, which increased to 14.3% after adjusting for gender, age and diet. Addition of the community disadvantage variable decreased the variance between areas by 4.8%, indicating that community disadvantage explained one-third of the area-level variance. Residents of under-resourced communities had significantly higher mean DMFT (β = 3.86, 95% CI 0.02, 7.70) after adjusting for gender, age and diet. Living in under-resourced communities was associated with greater DMFT among this disadvantaged population, indicating that policies aiming to reduce oral health-related inequalities among vulnerable groups may benefit from taking into account factors external to individual-level influences.

Universal for whom? Evaluating an urban Aboriginal population's access to a mainstream universal health home visiting program

To investigate access to a Universal Health Home Visit program for families of Aboriginal and non-Aboriginal infants and the effect of a one-off home visit on subsequent health service utilisation. A case-control study was undertaken drawing 175 Aboriginal infants from an Aboriginal birth cohort study and 352 matched non-Aboriginal infants. A structured file audit extracted data from child and family health nurse records. Receipt of home visit and effect on ongoing use of child and family nurses services was compared for Aboriginal and non-Aboriginal infants. Of the 527 infants, 279 (53.0%) were visited at home within 2 weeks. This is below NSW Health benchmarks. Significantly fewer Aboriginal infants (42.9%) compared to non-Aboriginal infants (58.0%) received a home visit within 2 weeks (P<0.01). Receipt of a single home visit did not affect future service use or the number of child health checks infants received. This study highlights the challenges of ensuring equitable access to a universal post-natal home visiting program. Assessing ways in which universal services are delivered to ensure equity of access may help to re-evaluate target expectations, reduce demand on nursing staff, improve targeting of vulnerable infants and help in further developing and implementing effective health policy.