Aboriginal Birth Cohort Study Research Articles

Racism as a determinant of social and emotional wellbeing for Aboriginal Australian youth

To explore the associations between self-reported racism and health and wellbeing outcomes for young Aboriginal Australian people. A cross-sectional study of 345 Aboriginal Australians aged 16-20 years who, as participants in the prospective Aboriginal Birth Cohort Study, were recruited at birth between 1987 and 1990 and followed up between 2006 and 2008. Self-reported social and emotional wellbeing using a questionnaire validated as culturally appropriate for the study's participants; recorded body mass index and waist-to-hip ratio. Self-reported racism was reported by 32% of study participants. Racism was significantly associated with anxiety (odds ratio [OR], 2.18 [95% CI, 1.37-3.46]); depression (OR, 2.16 [95% CI, 1.33-3.53]); suicide risk (OR, 2.32 [95% CI, 1.25-4.00]); and poor overall mental health (OR, 3.35 [95% CI, 2.04-5.51]). No significant associations were found between self-reported racism and resilience or any anthropometric measures. Self-reported racism was associated with poor social and emotional wellbeing outcomes, including anxiety, depression, suicide risk and poor overall mental health.

Iodine status of Aboriginal teenagers in the Darwin region before mandatory iodine fortification of bread

To determine the iodine status of participants in the Aboriginal Birth Cohort Study who resided in the Darwin Health Region (DHR) in the "Top End" of the Northern Territory prior to the introduction of mandatory iodine fortification of bread. Participants in our study had been recruited at birth and were followed up at a mean age of 17.8 years. Spot urine samples were collected and assessed for iodine concentration at a reference laboratory. The median urinary iodine concentration (MUIC) of residents of the DHR was calculated and compared with international criteria for iodine status. Analyses were conducted for subgroups living in urban areas (Darwin-Palmerston) and remote communities (rural with an Aboriginal council). We collected a repeat sample in a subset of participants to explore the impact of within-person variation on the results. MUIC for residents of the DHR. Urine specimens were provided by 376 participants in the DHR. Overall MUIC was 58 μg/L when weighted to the 2006 Census population. Urban boys had higher values (MUIC = 77 μg/L) than urban and remote-dwelling non-pregnant girls (MUIC = 55 μg/L), but all these groups were classified as mildly iodine deficient. Remote-dwelling boys had the lowest MUIC (47 μg/L, moderate deficiency). Pregnant girls and those with infants aged less than 6 months also had insufficient iodine status. Correction for within-person variation reduced the spread of the population distribution. Previously, iodine deficiency was thought to occur only in the south-eastern states of Australia. This is the first report of iodine deficiency occurring in residents of the NT. It is also the first study of iodine status in a defined Indigenous population. Future follow-up will reassess iodine status in this group after the introduction of iodine fortification of bread.

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

To describe the lipoprotein(a) (Lp(a))profile and its relationship to cardiovascular risk factors in Australian Aboriginal children. 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. 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. 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.

The Aboriginal Birth Cohort Study: When is a cohort study not a cohort design?

AbstractAims: The paper describes how a variety of different epidemiological study designs can be applied to data arising from a single prospective study.Methods: An overview of the data collection phases of the Aboriginal Birth Cohort Study is given. We illustrate how different research questions that require different analytical designs can be asked of the data collected in the present study.Results: With reference to five generic questions in health research, we showed how sixteen specific questions could be addressed in the Aboriginal Birth Cohort Study. These referred to a range of analytical designs.Conclusion: Readers need to take care not to confuse the overall design of a study with the design of a specific analysis. When conducting systematic literature reviews, studies should be classified according to the analytical design used in the specific report included in the review and not according to the design of the overall project.

A Retrospective Longitudinal Study of Caries Development in an Australian Aboriginal Birth Cohort

There are a limited number of longitudinal investigations that examine the progression of dental disease in an indigenous population. Dental examinations of a cohort of indigenous Australians born in Darwin (Australia) between 1987 and 1990 were conducted at ages 6–8 and 11–13 years as part of the Child Dental Health Survey, and 18–20 years as part of the longstanding prospective Aboriginal Birth Cohort (ABC) study. Data was available at all ages for 145 participants. The percent DMFT >0 increased from 17.2 to 44.1 to 81.4%, representing a linear trajectory, whereas mean DMFT increased from 0.3 to 1.0 to 5.6, representing an exponential trajectory. Both trends were significant. At age 18–20 years, the percent DMFT >0 among ABC study participants was 1.2 times that of their counterparts at a national level. The differences were more marked when dental caries severity was considered, with mean DMFT among 18- to 20-year-old ABC study participants being 1.7 times that of similarly aged adults at a national level. Most of this disparity was constituted by the decayed component, with ABC study participants having eight times the mean DT of their national-level counterparts. The findings indicate that Aboriginal young adults in this birth cohort experience a disproportionate amount of dental disease relative to their non-indigenous counterparts, and that this pattern is consistent across the life course.

Dental caries risk indicators among Australian Aboriginal young adults

To determine dental caries risk indicators among a birth cohort of Australian Aboriginal young adults (n=442). Data were from the Aboriginal Birth Cohort study, a prospective longitudinal investigation of Aboriginal individuals born 1987-1990 at an Australian regional hospital. Models representing demographic, socioeconomic, behavioural, dental service utilization and clinical oral health variables were tested using multivariate regression. The percent DT>0 was 72.9 (95% CI 68.7-77.1), mean DT was 4.19 (95% CI 3.8-4.6), percent DMFT>0 was 77.4 (95% CI 73.5-81.3) and mean DMFT was 4.84 (95% CI 4.4-5.3). After controlling for other covariates, risk indicators for percent DT>0 included soft drink consumption every day or a few times a week (PR 1.25, 95% CI 1.08-1.45), not consuming milk every day or a few times a week (PR 1.16, 95% CI 1.04-1.30) and sweet consumption every day or a few times a week (PR 1.18, 95% CI 1.04-1.33). Risk indicators for mean DT included sweet consumption every day or a few times a week (B=1.14, 95% CI 0.27-2.02), nonownership of a toothbrush (B=0.91, 95% CI 0.10-1.87) and presence of plaque (B=2.46, 95% CI 0.96-3.96). Those with 4 + occupants in their house the previous night had 1.2 times the prevalence of having DMFT>0 than their counterparts with less household occupants (95% CI 1.01-1.49). Percent DMFT>0 was also associated with consumption of soft drink every day or a few times a week (PR 1.18, 95% CI 1.04-1.34) and consumption of sweets every day or a few times a week (PR 1.23, 95% CI 1.10-1.37). Mean DMFT was higher among those who consumed sweets every day or a few times a week (B = 0.13, 95% CI 0.05-0.22) and who had dental anxiety (B=0.10, 95% CI 0.01-0.19). In an Australian Aboriginal young adult cohort, risk indicators for dental caries included social determinants such as household size, dietary behaviours such as regular consumption of soft drink and sweets, dental behaviour such as nonownership of a toothbrush and dental anxiety.

Clinical oral health outcomes in young Australian Aboriginal adults compared with national‐level counterparts

To compare clinical oral health outcomes between a birth cohort of young Australian Aboriginal adults and age-matched, national-level counterparts. Comparison of outcomes between the dental component of Wave-3 of the Aboriginal Birth Cohort (ABC) study--a cross-sectional study conducted between January 2006 and December 2007, nested within a prospective longitudinal investigation in the Northern Territory's Top End--and the 2004-06 National Survey of Adult Oral Health (NSAOH), a representative survey of the Australian population. Data were analysed for 442 ABC study participants and 202 NSAOH participants aged 16-20 years. Severity and prevalence of clinical oral health outcomes. The mean number of decayed teeth was 8.0 times higher among ABC study participants than NSAOH participants, while the prevalence of untreated decayed teeth was 3.1 times higher. ABC study participants experienced 10.8 times the prevalence of moderate or severe periodontal disease of NSAOH participants, and 1.9, 4.1 and 4.5 times the prevalence of calculus, plaque and gingivitis, respectively. Adverse clinical oral health outcomes were 2-11 times higher in a cohort of young Australian Aboriginal adults than their age-matched, nationally representative counterparts.

Substance use and periodontal disease among Australian Aboriginal young adults

To investigate the effects of tobacco, marijuana, alcohol and petrol sniffing on periodontal disease among Australian Aboriginal young adults. Cross-sectional nested within a long-standing prospective longitudinal study. Setting Aboriginal communities in Australia's Northern Territory. Members of the Aboriginal Birth Cohort study who were recruited from birth between January 1987 and March 1990 at the Royal Darwin Hospital, Northern Territory, Australia. Data were from wave III, when the mean age of participants was 18 years. Clinical dental examination and self-report questionnaire. Of 425 participants with complete data, 26.6% had moderate/severe periodontal disease. There was elevated risk of periodontal disease associated with tobacco [prevalence ratio (PR) = 1.59, 95% CI = 1.06-2.40], marijuana (PR = 1.44, 95% CI = 1.05-1.97) and petrol sniffing (PR = 1.83, 95% CI = 1.08-3.11), but not alcohol (PR = 0.92, 95% CI = 0.67-1.27). Stratified analysis showed that the effect of marijuana persisted among tobacco users (PR = 1.47, 95% CI 1.03-2.11). It was not possible to isolate an independent effect of petrol sniffing because all petrol sniffers used both marijuana and tobacco, although among smokers of both substances, petrol sniffing was associated with an 11.8% increased prevalence of periodontal disease. This is the first time that substance use has been linked with periodontal disease in a young Australian Aboriginal adult population, and the first time that petrol sniffing has been linked with periodontal disease in any population. The role of substance use in periodontal disease among this, and other, marginalized groups warrants further investigation.

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

BackgroundOral 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.MethodsData 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).ResultsThe 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).ConclusionsSevere 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.

Strong Souls: Development and Validation of a Culturally Appropriate Tool for Assessment of Social and Emotional Well-Being in Indigenous Youth

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. 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. 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. Strong Souls demonstrated validity, reliability and cultural appropriateness as a tool for screening for SEWB among Indigenous young people in the Northern Territory.

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.

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

BackgroundIn 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.MethodsProgressive steps in a multiphase protocol were used for tracing, with modifications for the expected rural or urban location of the participants.ResultsOf 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.ConclusionThe 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.

Apo-B/AI ratio identifies cardiovascular risk in childhood:The Australian Aboriginal Birth Cohort study

We describe the lipoprotein and apolipoprotein profiles and their relationship to cardiovascular risk factors in Australian Aboriginal children. This cross-sectional study within a longitudinal birth cohort study involved Australian Aboriginal children born between 1987 and 1990 and re-examined between 1998 and 2001. Height, weight, blood pressure, waist circumference, body fat percentage, cholesterol, triglycerides, HDL-c, LDL-c, apolipoprotein B and A1 were measured. Mean age was 11.4 years (52% male). Mean cholesterol, triglyceride, HDL-c and LDL-c did not differ from reference data. Measures of obesity, blood pressure and prevalence of the metabolic syndrome did not differ in those children with lipoproteins in the upper quartile of the cohort (lower quartile for HDL-c). Boys with an Apo-B/A1 ratio in the upper quartile of the cohort had higher BMI z-score, waist z-score, % body fat, diastolic blood pressure and frequency of the metabolic syndrome (p<0.05). In girls, waist circumference, % body fat and the prevalence of the metabolic syndrome was higher in those with an Apo-B/A1 ratio in the upper quartile (p<0.05).The Apo-B/A1 ratio may be useful to identify cardiovascular risk in Australian Aboriginal children and is suited to clinical practice as the assays are standardised, accurate, automated and a fasting sample is not required.

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

BackgroundA 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.MethodsThe 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.ResultsConventional 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.ConclusionOral 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.

P1-153 The Australian Aboriginal Birth Cohort Study, 1987 2007: Is birth size a predictor of depressive symptoms in young adulthood?

P1-153 The Australian Aboriginal Birth Cohort Study, 1987 2007: Is birth size a predictor of depressive symptoms in young adulthood?

P1-155 The Australian Aboriginal Birth Cohort Study, 1987 2007: Is birth size a predictor of oral health outcomes?

P1-155 The Australian Aboriginal Birth Cohort Study, 1987 2007: Is birth size a predictor of oral health outcomes?

P1-162 ApoB/A1 identifies cardiovascular risk in childhood: the Australian Aboriginal Birth Cohort Study

P1-162 ApoB/A1 identifies cardiovascular risk in childhood: the Australian Aboriginal Birth Cohort Study

5D-7 Arterial stiffness and birth weight: the Australian Aboriginal Birth Cohort Study 1987 2007

5D-7 Arterial stiffness and birth weight: the Australian Aboriginal Birth Cohort Study 1987 2007

The prevalence of anaemia depends on the definition: an example from the Aboriginal Birth Cohort Study

The cutoffs defining anaemia based on haemoglobin and haematocrit recommended by the World Health Organization (WHO) and the United States (US) are different. We compared the prevalences resulting from these definitions and explored the reasons for the variation observed. A cross-sectional survey within a cohort study of children recruited at birth at Royal Darwin Hospital. Subjects were interviewed in their homes or other convenient location and had a blood sample drawn. Five hundred and seventeen Australian Aboriginal children aged 9-13 years inclusive. Depending on the criterion used, the prevalence of anaemia in the total group ranged between 6% (95% confidence interval: 4.1-8.4%) and 24.4% (20.7-28.3). Using the WHO criteria, girls aged 12-13 years were identified as a target group, having a two- to-six fold higher prevalence than the other groups. When compared to the US criteria, boys aged 12-13 years had the highest prevalence of anaemia, although this was not significant. Simulations show that the WHO cutoffs are based on inconsistent centiles of the age-sex haemoglobin and haematocrit distributions, and that this largely explains the discrepant results. This variability in definition could lead to inappropriate identification of target groups for intervention programmes.