Australian Population Cohort Research Articles

Underemployment and mental health: comparing fixed-effects and random-effects regression approaches in an Australian working population cohort

ObjectivesUnderemployment occurs when workers are available for more hours of work than offered. It is a serious problem in many Organisation for Economic Co-operation and Development (OECD) countries, and particularly...

Effects of maltreatment and parental schizophrenia spectrum disorders on early childhood social-emotional functioning: a population record linkage study.

Childhood maltreatment and a family history of a schizophrenia spectrum disorder (SSD) are each associated with social-emotional dysfunction in childhood. Both are also strong risk factors for adult SSDs, and social-emotional dysfunction in childhood may be an antecedent of these disorders. We used data from a large Australian population cohort to determine the independent and moderating effects of maltreatment and parental SSDs on early childhood social-emotional functioning. The New South Wales Child Development Study combines intergenerational multi-agency data using record linkage methods. Multiple measures of social-emotional functioning (social competency, prosocial/helping behaviour, anxious/fearful behaviour; aggressive behaviour, and hyperactivity/inattention) on 69 116 kindergarten children (age ~5 years) were linked with government records of child maltreatment and parental presentations to health services for SSD. Multivariable analyses investigated the association between maltreatment and social-emotional functioning, adjusting for demographic variables and parental SSD history, in the population sample and in sub-cohorts exposed and not exposed to parental SSD history. We also examined the association of parental SSD history and social-emotional functioning, adjusting for demographic variables and maltreatment. Medium-sized associations were identified between maltreatment and poor social competency, aggressive behaviour and hyperactivity/inattention; small associations were revealed between maltreatment and poor prosocial/helping and anxious/fearful behaviours. These associations did not differ greatly when adjusted for parental SSD, and were greater in magnitude among children with no history of parental SSD. Small associations between parental SSD and poor social-emotional functioning remained after adjusting for demographic variables and maltreatment. Childhood maltreatment and history of parental SSD are associated independently with poor early childhood social-emotional functioning, with the impact of exposure to maltreatment on social-emotional functioning in early childhood of greater magnitude than that observed for parental SSDs. The impact of maltreatment was reduced in the context of parental SSDs. The influence of parental SSDs on later outcomes of maltreated children may become more apparent during adolescence and young adulthood when overt symptoms of SSD are likely to emerge. Early intervention to strengthen childhood social-emotional functioning might mitigate the impact of maltreatment, and potentially also avert future psychopathology.

Low level autoantibodies can be frequently detected in the general Australian population

The aim of this study was to determine the prevalence and type of autoantibodies in a general Australian population cohort. Samples collected from 198 individuals included in a cross sectional Busselton Health Study were tested using autoantibody assays routinely performed at Clinical Immunology, PathWest Laboratory Medicine, Western Australia. At least one autoantibody was detected in 51.5% of individuals (males=45.1%, females=58.3%). The most frequently detected serum autoantibodies were anti-beta-2-glycoprotein I (12.1%) followed by anti-smooth muscle (11.6%) and anti-thyroid peroxidase (8.6%). Vasculitis associated anti-neutrophil cytoplasmic antibodies were present in 5.1%, while anti-nuclear antibodies were detected in 8.6% of individuals. Notably, 65% of positive results were detected at low levels with the exception of anti-myeloperoxidase and anti-beta 2 glycoprotein I IgG antibodies. Autoantibodies are commonly detected at low levels in a predominantly Australian or European population cohort. No large Australian study has yet provided these data for contemporary routine tests. This paper gives important information on the background frequency of autoantibodies in the general population. Due to the nature of this study we are unaware of whether these individuals have subsequently developed an autoimmune disease, however this was not clinically diagnosed at the time of sample collection.

The role of preschool in promoting children’s healthy development: Evidence from an Australian population cohort

A growing body of evidence suggests that engagement with quality early childhood education and care (ECEC) programs such as preschool can enhance children’s early development. The Australian Early Development Census (AEDC) provides a unique opportunity to explore the relationship between ECEC and children’s developmental outcomes in a full population cohort of Australian school entrants. The AEDC is a teacher-rated checklist that provides data on ECEC experiences in the year before starting school, as well as five important domains of child development at school entry: physical health and wellbeing, social competence, emotional maturity, language and cognitive skills, and communication skills and general knowledge. In 2009, the AEDC was completed for 97.5% of Australian children in their first year of formal schooling (N=261,147; M=5 years, 7 months of age). Logistic regression analyses revealed that attendance at preschool was associated with reduced odds (OR=0.69, p<0.001 to OR=0.40, p<0.001) of being in the vulnerable range (<10th percentile) on four of the five AEDC domains (with the exception of emotional maturity; OR=0.89, p=0.002), compared to other ECEC experiences, or care exclusively by parents. Subsequent analyses revealed that this effect was evident for children living in both advantaged and disadvantaged communities. Together, the results suggest that engagement with preschool programs in Australia may present a plausible, equitable, and modifiable approach to improving children's developmental outcomes.

Longitudinal analysis of relationships between social support and general health in an Australian population cohort of young women.

The influence of social support on health and quality of life has been well documented. There is less evidence on whether health status affects social support, and little is known about longitudinal relationships between social support and health in early adulthood. This study investigates these associations using both concurrent and time-lagged measures at 5 time-points over 12 years during early adulthood. A population-based cohort of 9,758 young women from the Australian Longitudinal Study on Women's Health was used. Women were aged 22-27 in 2000 and 35-39 in 2012. The General Health subscale of the SF-36 and the MOS Social Support Survey 6-item Scale were used, with scores standardised to a range of 0-100. Longitudinal tobit models were used, because both social support and general health data were left skewed, with marked ceiling effects. All models were adjusted for status of the outcome of interest at the immediately previous survey. With both concurrent and time-lagged measures, there was a statistically significant difference in mean general health scores across social support quintiles after adjusting for demographic and behavioural covariates: lower general health was associated with lower social support. In reverse, social support mean scores were also significantly different across general health quintiles in both concurrent and time-lagged fully adjusted models. Social support is significantly associated with both current and subsequent general health in early adulthood. The significance of the reverse associations indicates that the two mutually influence each other. This study highlights the importance of social support as a health-related quality of life issue.

Early development of emerging and English-proficient bilingual children at school entry in an Australian population cohort

Children who enter school with limited proficiency in the language of instruction face a range of challenges in negotiating this new context, yet limited data have been available to describe the early developmental outcomes of this subpopulation in the Australian context. The Australian Early Development Index (AEDI) is a teacher-rated checklist that measures five important domains of child development: physical health and wellbeing, social competence, emotional maturity, language and cognitive skills, and communication skills and general knowledge. In 2009, the AEDI was completed for 97.5% of Australian children in their first year of schooling (N = 261,147; M = 5 years, 7 months of age), providing a unique opportunity to explore the cross-sectional associations between language background, proficiency in English, and early developmental outcomes at the population-level. Logistic regression analyses revealed that, compared to their peers from English-speaking backgrounds, bilingual children who were not yet proficient in English had substantially higher odds of being in the “vulnerable” range (bottom 10th percentile) on the AEDI domains (OR = 2.88, p < .001, to OR = 7.49, p < .001), whereas English-proficient bilingual children had equal or slightly lower odds (OR = .84, p < .001, to OR = .97, ns). Future research with longitudinal data is now needed to establish causal pathways and explore long term outcomes.

Australian Population Cohort Study of Newly Arrived Refugee Children

Predeparture medical screening and measles-mumps-rubella vaccination are routinely given to refugee children before departure from most transit countries en route to Australia. The purpose of this study was to evaluate the effectiveness of this single measles-mumps-rubella vaccine and the reliability of its documentation. This is important in determining refugees' susceptibility to measles and rubella and the risk to the nonvaccinated community. We analyzed measles and rubella serology in a comprehensively screened population of newly arrived refugees. We reviewed seropositivity rates based on age, sex, country of departure and vaccine documentation. Of 164 children screened, 139 (84.8%) were immune to rubella; 143 (87.7%) to measles and 119 (73.0%) to both. There was no significant difference in immunity among those of different ages or those departing different continents. Immunity rates among those with documented measles-mumps-rubella tended to be higher: 91.1% for rubella, 89.1% for measles and 80.0% for both diseases, but this did not reach significance at the 5% level. There was a significant difference between males (65.9%) and females (81.3%) immune to both diseases (P = 0.042). This cohort demonstrated similar measles and rubella seropositivity rates to those of the Australian population, but lower rates than population seroconversion studies, which have been estimated at 95%. Males were less likely to be immune. Rates in those with documented vaccination approximated seroconversion studies. This confirms the appropriateness of current guidelines which suggest that immunization is not required in the face of documented prior vaccination, but is required without such documentation.

Using the Gross Motor Function Classification System to describe patterns of motor severity in cerebral palsy

The aim of this study was to describe the distribution of motor severity levels and temporal trends in an Australian population cohort and to review the distribution of Gross Motor Function Classification System (GMFCS) levels across cerebral palsy (CP) registries worldwide. Data were extracted from the Victorian Cerebral Palsy Register for 3312 individuals (1852 males, 1460 females; mean age 21y 2mo [SD 9 y 6 mo]) with non-postneonatally acquired CP, born between 1970 and 2003. The proportions of each motor severity level were calculated and logistic regression analyses were used to assess trends over time. A systematic review of the literature was undertaken and GMFCS data were extracted based on previously devised criteria. The proportions were plotted and the degree of heterogeneity was assessed for each level. Population data from Victoria suggested a proportional increase in mild motor impairment (GMFCS levels I/II) from 54% of all cases of CP in the 1970s to 61% in the 2000s. For nine CP registries worldwide, the mean proportions of each GMFCS level, from level I to V, were 34.2%, 25.6%, 11.5%, 13.7%, and 15.6% respectively. There was substantial heterogeneity between registries for all levels except level III. Despite the usefulness and reported reliability of the GMFCS, substantial variability was found in the distribution of GMFCS levels between population registries, particularly between levels I and II, suggesting greater classification uncertainty between these levels. Further research would be useful to determine whether routine collection of extra clinical information may facilitate more reliable classification.

The health loss from ischemic stroke and intracerebral hemorrhage: evidence from the North East Melbourne Stroke Incidence Study (NEMESIS)

BackgroundPeople suffering different types of stroke have differing demographic characteristics and survival. However, current estimates of disease burden are based on the same underlying assumptions irrespective of stroke type. We hypothesized that average Quality Adjusted Life Years (QALYs) lost from stroke would be different for ischemic stroke and intracerebral hemorrhage (ICH).MethodsWe used 1 and 5-year data collected from patients with first-ever stroke participating in the North East Melbourne Stroke Incidence Study (NEMESIS). We calculated case fatality rates, health-adjusted life expectancy, and quality-of-life (QoL) weights specific to each age and gender category. Lifetime 'health loss' for first-ever ischemic stroke and ICH surviving 28-days for the 2004 Australian population cohort was then estimated. Multivariable uncertainty analyses and sensitivity analyses (SA) were used to assess the impact of varying input parameters e.g. case fatality and QoL weights.ResultsPaired QoL data at 1 and 5 years were available for 237 NEMESIS participants. Extrapolating NEMESIS rates, 31,539 first-ever strokes were expected for Australia in 2004. Average discounted (3%) QALYs lost per first-ever stroke were estimated to be 5.09 (SD 0.20; SA 5.49) for ischemic stroke (n = 27,660) and 6.17 (SD 0.26; SA 6.45) for ICH (n = 4,291; p < 0.001). QALYs lost also differed according to gender for both subtypes (ischemic stroke: males 4.69 SD 0.38, females 5.51 SD 0.46; ICH: males 5.82 SD 0.67, females 6.50 SD 0.40).DiscussionPeople with ICH incurred greater loss of health over a lifetime than people with ischemic stroke. This is explained by greater stroke related case fatality at a younger age, but longer life expectancy with disability after the first 12 months for people with ICH. Thus, studies of disease burden in stroke should account for these differences between subtype and gender. Otherwise, in countries where ICH is more common, health loss for stroke may be underestimated. Similar to other studies of this type, the generalisability of the results may be limited. Sensitivity and uncertainty analyses were used to provide a plausible range of variation for Australia. In countries with demographic and life expectancy characteristics comparable to Australia, our QoL weights may be reasonably applicable.