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Siblings of individuals with neurodevelopmental conditions (NDCs) are exposed to unique family environments and experience a range of psychosocial risk and resilience factors. Networks of self-reported risk, resilience, and neuropsychiatric variables were estimated for siblings of individuals with (n = 235) and without (n = 480) NDCs (N = 715, mean age 22.40 years, 76% female, 74% White Caucasian). The NDC group reported more depressive (g = 0.39) and anxious (g = 0.43) symptoms than controls, and 71.5% of the NDC group reported at least one neuropsychiatric diagnosis compared to 36.9% of controls. Self-reported sleep and post-traumatic stress disorders were high amongst NDC siblings. Everyday executive functioning difficulties (cognitive inflexibility, hyperactivity/impulsivity) and emotion dysregulation were the most influential transdiagnostic risk factors for poorer functioning within the NDC group network.

Siblings of persons with neurodevelopmental conditions (NDCs) have increased risk of poorer psychosocial functioning. This systematic review evaluated quantitative and qualitative evidence on sibling mental health and wellbeing outcomes following psychosocial interventions and the risk and protective factors associated with post-intervention outcomes. From 2025 identified studies published from 1991 to 2022 across ten databases, 24 studies were included. The largest immediate post-intervention improvements were in self-esteem, social wellbeing and knowledge of NDCs. The most sustained improvements in intervention groups at follow-up periods were in emotional and behavioural adjustment and NDC knowledge. There were positive, but small, differences in favour of the intervention groups on knowledge of NDCs, self-esteem, coping and the sibling relationship as compared to waitlist control groups. Psychosocial interventions for siblings are heterogeneous, and more data, including consideration of unique family circumstances, are needed to improve reporting and replicability, to measure effectiveness and tailor necessary supports.

Objective The behavioral phenotype of neurogenetic disorders associated with intellectual disability often includes psychiatric comorbidity. The objectives of this systematic review and meta-analysis were to systematically review the prevalence of psychiatric disorders and symptoms in children and adolescents with these disorders and compare phenotypic signatures between syndromes. Method MEDLINE and PsycINFO databases were searched for articles from study inception to December 2018. Eligible articles were peer reviewed, were published in English, and reported prevalence data for psychiatric disorders and symptoms in children and adolescents aged 4 to 21 years using a formal psychiatric assessment or a standardized assessment of mental health symptoms. Pooled prevalence was determined using a random-effects meta-analysis in studies with sufficient data. Prevalence estimates were compared with general population data using a test of binomial proportions. Results Of 2,301 studies identified for review, 39 articles were included in the final pool, which provided data on 4,039 children and adolescents. Ten syndromes were represented, and five were predominant: Down syndrome, 22q11.2 deletion syndrome, fragile X syndrome, Williams syndrome, and Prader-Willi syndrome. The Child Behavior Checklist was the most commonly used assessment tool for psychiatric symptoms. The pooled prevalence with total scores above the clinical threshold was lowest for Down syndrome (32% [95% confidence interval, 19%-44%]) and highest for Prader-Willi syndrome (74% [95% CI, 65%-82%]) with each syndrome associated with significantly higher prevalence than in the general population. Parallel trends were observed for the internalizing and externalizing domains and social subscale scores. Conclusion Differential vulnerability for psychiatric phenotype expression across the disorders was observed. Syndromes with higher levels of social ability or competence appear to offer relative protection against developing psychopathology. This preliminary finding merits further exploration.

This pre-registered systematic review synthesised and evaluated the existing literature on self-reported mental health and wellbeing of siblings of individuals with neurodevelopmental conditions (NDCs).From 2437 identified studies published 2000-2022, 81 studies were included: 14 population- or cohort-based, 39 quantitative, 7 mixed method, and 21 qualitative outcome studies.Seven sibling mental health (any psychiatric disorder, anxiety, depression, bipolar disorder, schizophrenia, internalising and externalising difficulties) and five wellbeing indicators were identified (quality of life, emotional adjustment, social wellbeing, somatic/physical wellbeing, and resilience/growth). Overall, siblings had increased risk of any psychiatric disorder, but they also reported experiences of growth and resilience, primarily in qualitative studies. 41 risk factors and 24 resilience factors associated with these outcomes were identified; the most frequently cited risk factor was symptom severity of the NDC sibling, while the most common resilience factor was adaptive/active coping at the individual sibling level. Studies showed high methodological heterogeneity and 90 different self-report measures were used.Sibling mental health indictors are heterogeneous and cumulative risk factors may result in poorer wellbeing. There is a need for consistent reporting of family and sibling characteristics, a strengths-based approach to assessment, and identification of protective and resilience-promoting factors.

Motor impairment is not currently included in the diagnostic criteria or evaluation of autism. This reflects the lack of large-scale studies demonstrating its prominence to advocate for change. We examined the prevalence of motor difficulties at the time of diagnosis in a large sample of children with autism utilizing standardized assessment, and the relationship between motor difficulties, core autism symptomology, and other prominent clinical features. Vineland Adaptive Behavior Scales were administered to children from the Western Australian Register for Autism Spectrum Disorders aged ≤6 years (N = 2,084; 81.2% males, 18.8% females). Prevalence of motor difficulties was quantified based on scores from the motor domain of the Vineland and then compared to other domains of functioning within the Vineland (communication, daily living, and socialization), the DSM criteria, intellectual level, age, and gender. Scores on the Vineland indicated that 35.4% of the sample met criteria for motor difficulties (standard score70), a rate almost as common as intellectual impairment (37.7%). Motor difficulties were reported by diagnosing clinicians in only 1.34% of cases. Motor difficulties were common in those cases meeting diagnostic criteria for impairments in nonverbal behavior and the presence of restricted and repetitive behaviors. The prevalence of motor difficulties also increased with increasing age of diagnosis (P 0.001). Findings from the present study highlight the need for further consideration of motor difficulties as a distinct specifier within the diagnostic criteria for ASD. Autism Res 2020, 13: 298-306. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: In this population-based cohort that included 2,084 children with autism aged ≤6 years, over one-third met the criteria for motor difficulties, a rate almost as common as intellectual disability. This study demonstrates that motor difficulties are a prominent feature of the autism phenotype requiring further consideration in both the diagnostic criteria and evaluation of autism.

Data linkage holds great promise for generating new information about people with intellectual and developmental disabilities (IDD) as a population, yet few centers have developed the infrastructure to utilize this methodology. Two examples, from Canada and Australia, describe their efforts in building data linkage capabilities, and how linked databases can be used to identify persons with IDD and used for population-based research. The value of data linkage is illustrated through new estimates of prevalence of IDD; health service utilization patterns; associations with sociodemographic characteristics, and with physical and mental health conditions (e.g., chronic diseases, injury, fertility, and depression); and findings on equity in medical treatments. Examples are provided of findings used for governmental policy and program planning.

Aim To compare hospital admission patterns after the first year of life in Australian children with developmental disabilities and children with no known disability, according to maternal country of birth and Indigenous status. Method This was a retrospective cohort study using linked data across health, disability, and hospital admission databases. The study investigated 656 174 children born in Western Australia between 1983 and 2008 with a total of 1 091 834 records of hospital admissions. Results Children with no known disability born to Indigenous mothers had the highest rate of hospital admissions compared to children of non-Indigenous mothers. Children of foreign-born mothers from low-income countries had the highest rate of hospital admissions if disability was present. Children with cerebral palsy (CP) with or without associated intellectual disability had the highest rate of hospital admissions among children with developmental disability, especially if mothers were foreign-born. Interpretation Children with CP and intellectual disability, particularly from minority backgrounds (Indigenous Australian and foreign-born mothers), were at higher risk of being admitted to hospital after the first year of life. What this paper adds Hospital admissions in Australian children with and without disabilities differ according to maternal country of birth. Hospital admission rates in children without a developmental disability were greatest for Australian-born Indigenous children. Disabled Australian-born children of foreign-born mothers from low-income countries had the highest hospital admission rates. Hospital admission risk was greatest for Australian-born children with cerebral palsy, especially if mothers were foreign-born.

Objective Familial recurrence risk is an important population-level measure of the combined genetic and shared familial liability of autism spectrum disorder (ASD). Objectives were to estimate ASD recurrence risk among siblings and cousins by varying degree of relatedness and by sex. Method This is a population-based cohort study of livebirths from 1998 to 2007 in California, Denmark, Finland, Israel, Sweden and Western Australia followed through 2011 to 2015. Subjects were monitored for an ASD diagnosis in their older siblings or cousins (exposure) and for their ASD diagnosis (outcome). The relative recurrence risk was estimated for different sibling and cousin pairs, for each site separately and combined, and by sex. Results During follow-up, 29,998 cases of ASD were observed among the 2,551,918 births used to estimate recurrence in ASD and 33,769 cases of childhood autism (CA) were observed among the 6,110,942 births used to estimate CA recurrence. Compared with the risk in unaffected families, there was an 8.4-fold increase in the risk of ASD following an older sibling with ASD and a 17.4-fold increase in the risk of CA following an older sibling with CA. A 2-fold increase in the risk for cousin recurrence was observed for the 2 disorders. There also was a significant difference in sibling ASD recurrence risk by sex. Conclusion The present estimates of relative recurrence risks for ASD and CA will assist clinicians and families in understanding autism risk in the context of other families in their population. The observed variation by sex underlines the need to deepen the understanding of factors influencing ASD familial risk.

‘High functioning autism’ is a term often used for individuals with autism spectrum disorder without an intellectual disability. Over time, this term has become synonymous with expectations of greater functional skills and better long-term outcomes, despite contradictory clinical observations. This study investigated the relationship between adaptive behaviour, cognitive estimates (intelligence quotient) and age at diagnosis in autism spectrum disorder. Participants ( n = 2225, 1–18 years of age) were notified at diagnosis to a prospective register and grouped by presence ( n = 1041) or absence ( n = 1184) of intellectual disability. Functional abilities were reported using the Vineland Adaptive Behaviour Scales. Regression models suggested that intelligence quotient was a weak predictor of Vineland Adaptive Behaviour Scales after controlling for sex. Whereas the intellectual disability group’s adaptive behaviour estimates were close to reported intelligence quotients, Vineland Adaptive Behaviour Scales scores fell significantly below intelligence quotients for children without intellectual disability. The gap between intelligence quotient and Vineland Adaptive Behaviour Scales scores remained large with increasing age at diagnosis for all children. These data indicate that estimates from intelligence quotient alone are an imprecise proxy for functional abilities when diagnosing autism spectrum disorder, particularly for those without intellectual disability. We argue that ‘high functioning autism’ is an inaccurate clinical descriptor when based solely on intelligence quotient demarcations and this term should be abandoned in research and clinical practice.

Background Birth order effects have been linked to variability in intelligence, educational attainment and sexual orientation. First- and later-born children have been linked to an increased likelihood of an Autism Spectrum Disorder (ASD) diagnosis, with a smaller body of evidence implicating decreases in cognitive functioning with increased birth order. The present study investigated the potential association between birth order and ASD diagnostic phenotypes in a large and representative population sample. Methods Data were obtained from an ongoing prospective diagnostic registry, collected between 1999 and 2017, including children (1-18 years of age, n = 5,404) diagnosed with ASD in the state of Western Australia. Children with ASD were ranked relative to sibling's birth to establish birth order within families at time of ASD diagnosis. Information reported to the registry by health professionals at the time of diagnostic evaluation included demographic and family characteristics, functional abilities and intellectual capacity. Results Adaptive functioning and intelligence scores decreased with increasing birth order, with later-born children more likely to have an intellectual disability. Compared to first-born children with siblings, first-born children without siblings at the time of diagnosis also exhibited decreased cognitive functioning. Conclusions These findings demonstrate for the first time an association between increasing birth order and variability in ASD clinical phenotypes at diagnosis, with potential evidence of reproductive curtailment in children without siblings. Taken together, these findings have significant implications for advancing understanding about the potential mechanisms that contribute to heterogeneity in ASD clinical presentations as a function of birth order and family size.

Background:Children and adolescents with intellectual disability are at risk of developing psychiatric symptoms and disorders; yet, the estimates reported in the literature have been inconsistent, presenting a potential barrier for service planning and delivery. Sources of variability could arise from differences in measurement instruments as well as subgroup membership by severity of intellectual disability, gender and age. This systematic review aimed to address these gaps.Method:MEDLINE and PsycINFO databases were searched from inception to 2018 and selected studies were reviewed. Studies were included if they reported point prevalence estimates of mental health symptomology or diagnoses in a general population of 6- to 21-year-old individuals with intellectual disability. The Joanna Briggs Institute Prevalence Critical Appraisal Checklist was applied to eligible papers to appraise their scientific strength. Pooled prevalence for mental health symptomology was determined using a random-effects meta-analysis.Results:A total of 19 studies were included, including 6151 children and adolescents. The pooled prevalence estimate captured by the Developmental Behaviour Checklist was 38% (95% confidence interval = [31, 46]), contrasting with 49% (95% confidence interval = [46, 51]) captured by the Child Behaviour Checklist; both rates were higher than a non-intellectual disability population. Severity of intellectual disability did not significantly influence the Developmental Behaviour Checklist risks. Insufficient data were available to conduct statistical analyses on the effects of age, gender and socioeconomic status. Of diagnosed psychiatric disorders, attention deficit/hyperactivity disorder (30%), conduct disorder (3–21%) and anxiety disorders (7–34%) were the most prevalent conditions.Conclusion:This review consists of the largest sample hitherto evaluated. In the intellectual disability population, mental health comorbidities could be better detected by a symptom phenotype than a psychiatric diagnostic phenotype. Crucially, future research needs to address the effect of measurement validity in the intellectual disability population. Estimated prevalence rates were high compared to the general population, indicating the importance of systematic screening, case detection and appropriate management.

BACKGROUND Positive health outcomes have been observed following gastrostomy insertion in children with intellectual disability, which is being increasingly used at younger ages to improve nutritional intake. This study investigated the effect of gastrostomy insertion on survival of children with severe intellectual disability. METHODS We used linked disability and health data of children and adolescents who were born in Western Australia between 1983 and 2009 to compare survival of individuals with severe intellectual disability by exposure to gastrostomy status. For those born in 2000-2009, we employed propensity score matching to adjust for confounding by indication. Effect of gastrostomy insertion on survival was compared by pertinent health and sociodemographic risk factors. RESULTS Compared with children born in the 1980s-1990s, probability of survival following first gastrostomy insertion for those born in 2000-2009 was higher (2 years: 94% vs. 83%). Mortality risk was higher in cases than that in their matched controls (hazard ratio 2.9, 95% confidence interval 1.1, 7.3). The relative risk of mortality (gastrostomy vs. non-gastrostomy) may have differed by sex, birthweight and time at first gastrostomy insertion. Respiratory conditions were a common immediate or underlying cause of death among all children, particularly among those undergoing gastrostomy insertion. CONCLUSIONS Whilst gastrostomy insertion was associated with lower survival rates than children without gastrostomy, survival improved with time, and gastrostomy afforded some protection for the more vulnerable groups, and earlier use appears beneficial to survival. Specific clinical data that may be used to prioritise the need for gastrostomy insertion may be responsible for the survival differences observed.

ObjectiveChildren with intellectual disability and marked feeding difficulties may undergo gastrostomy insertion to assist with their nutritional and medication needs. Use has increased recently for younger children, and it is intended to provide long-term support. This study explored the perceived value of gastrostomy for the quality of life (QOL) of children with intellectual disabilities and their families.MethodsTwenty-one primary caregivers of children with intellectual disability aged 2–18 years participated in semistructured telephone interviews. Data were analysed using directed content analysis, and data were coded to existing QOL domains relevant to children with intellectual disability and their families.ResultsBenefits in each of the child and family QOL domains were represented in the interview data. For children, the impacts of gastrostomy for the physical health domain were predominant, supplemented by experiences of value for emotional well-being, social interactions, leisure activities and independence. For families, gastrostomy was integrated into multiple aspects of QOL relating to family interactions, parenting, resources and supports, health and safety, and advocacy support for disability. Shortcomings related to difficulties with equipment and complications.ConclusionsOur comprehensive overview of the value of gastrostomy for children with intellectual disability and their families was classified within a QOL framework. Gastrostomy was mainly supportive over long time periods across many QOL domains. Findings will be of use to patient counselling and education and the development of family support resources.

The largest group of recipients of pediatric gastrostomy have neurological impairment with intellectual disability (ID). This study investigated trends in first gastrostomy insertion according to markers of disadvantage and ID etiology. Linked administrative and health data collected over a 32-year study period (1983-2014) for children with ID born between 1983 and 2009 in Western Australia were examined. The annual incidence rate change over calendar year was calculated for all children and according to socioeconomic status, geographical remoteness, and Aboriginality. The most likely causes of ID were identified using available diagnosis codes in the linked data set. Of 11,729 children with ID, 325 (2.8%) received a first gastrostomy within the study period. The incidence rate was highest in the 0-2 age group and there was an increasing incidence trend with calendar time for each age group under 6 years of age. This rate change was greatest in children from the lowest socioeconomic status quintile, who lived in regional/remote areas or who were Aboriginal. The two largest identified groups of ID were genetically caused syndromes (15.1%) and neonatal encephalopathy (14.8%).Conclusion: Gastrostomy is increasingly used in multiple neurological conditions associated with ID, with no apparent accessibility barriers in terms of socioeconomic status, remoteness, or Aboriginality. What is Known: • The use of gastrostomy insertion in pediatrics is increasing and the most common recipients during childhood have neurological impairment, most of whom also have intellectual disability (ID). What is New: • Nearly 3% of children with ID had gastrostomy insertion performed, with the highest incidence in children under 3 years of age. • Gastrostomy use across different social groups was equitable in the Australian setting.

Objective Gastrostomy insertion in pediatrics is usually used in children with complex needs and severe disability. The accessibility and acceptance of the procedure is increasing but population-based occurrence data are lacking and there is limited understanding of its use in clinical subgroups. Methods This birth cohort study investigated the trends in first gastrostomy insertion among a pediatric population born between 1983 and 2009 in Western Australia using linked administrative and health data collected over a 32-year period (1983-2014). Indications were identified using diagnosis codes from linked hospitalization data and grouped according to a refined classification system. Age and birth cohort patterns of first gastrostomy use, over calendar year and age respectively, were described. Results Of the 690,688 children born between 1983 and 2009, 466 underwent a gastrostomy insertion. Overall, the prevalence was approximately 7 cases per 10,000 births. New gastrostomy insertions were increasingly performed in children during the preschool years over calendar years and in successive birth cohorts. Children with a neurological disorder constituted the largest group receiving gastrostomy (n = 372; 79.8) including 325 (87.4%) with comorbid intellectual disability. Conclusions New gastrostomy insertion among children who require long-term enteral feeding support increased over the study period. The procedure is most often performed in the context of severe neurological disability, including intellectual disability, and offers families potential for long-term home-based management of feeding difficulties.

This paper systematically reviewed the literature from 2002 to 2016 describing the risks of autism spectrum disorder, intellectual disability and attention deficit hyperactivity disorder in children of immigrant and refugee backgrounds. Compared to children of non-immigrant mothers, 10 studies found increased risk of autism and intellectual disability and four studies found increased risk of autism without identifying concomitant intellectual disability. Very high risks were observed if the mother’s country of birth was a developing country or region. One study found higher risk of attention deficit hyperactivity disorder in a sample of children who were refugees. Children of immigrant and refugee backgrounds from developing countries had greater risks of a neurodevelopmental disorder compared to their peers whose mother was locally born.

The increasing prevalence of Autism Spectrum Disorders (ASD) may in part be due to a shift in the diagnostic threshold that has led to individuals with a less severe behavioral phenotype receiving a clinical diagnosis. This study examined whether there were changes over time in the qualitative and quantitative phenotype of individuals who received the diagnosis of Autistic Disorder. Data were from a prospective register of new diagnoses in Western Australia (n = 1252). From 2000 to 2006, we examined differences in both the percentage of newly diagnosed cases that met each criterion as well as severity ratings of the behaviors observed (not met, partially met, mild/moderate and extreme). Linear regression determined there was a statistically significant reduction from 2000 to 2006 in the percentage of new diagnoses meeting two of 12 criteria. There was also a reduction across the study period in the proportion of new cases rated as having extreme severity on six criteria. There was a reduction in the proportion of individuals with three or more criteria rated as extreme from 2000 (16.0%) to 2006 (1.6%), while percentage of new cases with no “extreme” rating on any criteria increased from 58.5% to 86.6% across the same period. This study provides the first clear evidence of a reduction over time in the behavioral severity of individuals diagnosed with Autistic Disorder during a period of stability in diagnostic criteria. A shift toward diagnosing individuals with less severe behavioral symptoms may have contributed to the increasing prevalence of Autistic Disorder diagnoses. Autism Res 2017. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Objective Restricted and repetitive pattern of behaviours and interests (RRB) are a cardinal feature of autism spectrum disorder (ASD), but there remains uncertainty about how these diverse behaviours vary according to individual characteristics. This study provided the largest exploration to date of the relationship between Repetitive Motor Behaviours, Rigidity/Insistence on Sameness and Circumscribed Interests with other individual characteristics in newly diagnosed individuals with ASD. Method Participants (N = 3,647; 17.7% females; Mage = 6.6 years [SD = 4.7]) were part of the Western Australian (WA) Register for ASD, an independent, prospective collection of demographic and diagnostic data of newly diagnosed cases of ASD in WA. Diagnosticians rated each of the DSM‐IV‐TR criteria on a 4‐point Likert severity scale, and here we focused on the Repetitive Motor Behaviours, Insistence on Sameness and Circumscribed Interests symptoms. Results The associations between RRB domains, indexed by Kendall's Tau, were weak, ranging from non‐significant for both Circumscribed Interests and Repetitive Motor Behaviours to significant (.20) for Insistence on Sameness and Repetitive Motor Behaviours. Older age at diagnosis was significantly associated with lower Circumscribed Interests and significantly associated with higher Insistence on Sameness and Repetitive Motor Behaviours. Male sex was significantly associated with higher Repetitive Motor Behaviours but not Insistence on Sameness or Circumscribed Interests. Conclusions The pattern of associations identified in this study provides suggestive evidence for the distinctiveness of Repetitive Motor Behaviours, Insistence on Sameness and Circumscribed Interests, highlighting the potential utility of RRB domains for stratifying the larger ASD population into smaller, more phenotypically homogeneous subgroups that can help to facilitate efforts to understand diverse ASD aetiology and inform design of future interventions.

Background To compare the prevalence of preterm birth, post term birth, intra-uterine growth restriction and distribution of Apgar scores in offspring of foreign-born women in Western Australia with that of their Australian-born non-Indigenous and Indigenous counterparts. Methods A population-based linked data study, involving 767,623 singleton births in Western Australia between 1980 and 2010 was undertaken. Neonatal outcomes included preterm birth, post term births, intra-uterine growth restriction (assessed using the proportion of optimal birth weight) and low Apgar scores. These were compared amongst foreign-born women from low, lower-middle, upper middle and high income countries and Australian-born non-Indigenous and Indigenous women over two different time periods using multinomial logistic regression adjusted for covariates. Results Compared with Australian born non-Indigenous women, foreign-born women from low income countries were at some increased risk of extreme preterm (aRRR 1.59, 95% CI 0.87, 2.89) and very early preterm (aRRR 1.63, 95% CI 0.92, 2.89) births during the period from 1980 to 1996. During the period from 1997 to 2010 they were also at some risk of extreme preterm (aRRR 1.42, 95% CI 0.98, 2.04) very early preterm (aRRR 1.34, 95% CI 1.11, 1.62) and post term birth (aRRR 1.93, 95% CI 0.99, 3.78). During this second time period, other adverse outcomes for children of foreign-born women from low income and middle income countries included increases in severe (aRRR 1.69, 95% CI 1.30, 2.20; aRRR 1.72, 95% CI 1.53, 1.93), moderate (aRRR 1.54, 95% CI 1.32, 1.81; aRRR 1.59, 95% CI 1.48, 1.70) and mild (aRRR 1.28, 95% CI 1.14, 1.43; aRRR 1.31, 95% CI 1.25, 1.38) IUGR compared to children of Australian-born non-Indigenous mothers. Uniformly higher risks of adverse outcomes were also demonstrated for infants of Indigenous mothers. Conclusions Our findings illustrate the vulnerabilities of children born to foreign women from low and middle-income countries. The need for exploratory research examining mechanisms contributing to poorer birth outcomes following resettlement in a developed nation is highlighted. There is also a need to develop targeted interventions to improve outcomes for these women and their families. Electronic supplementary material The online version of this article (10.1186/s12884-019-2437-x) contains supplementary material, which is available to authorized users.

Objective To examine the frequency of hospital admissions before and after gastrostomy insertion in children with severe intellectual disability. Study design We conducted a retrospective cohort study using linked health administrative and disability data from Western Australia (WA) and New South Wales (NSW). Children born between 1983 and 2009 in WA and 2002 and 2010 in NSW who had a gastrostomy insertion performed (n = 673 [WA, n = 325; NSW, n = 348]) by the end of 2014 (WA) and 2015 (NSW) were included. Conditional Poisson regression models were used to evaluate the age-adjusted effect of gastrostomy insertion on acute hospitalizations for all-cause, acute lower respiratory tract infections (LRTI), and epilepsy admissions. Results The incidence of all-cause hospitalizations declined at 5 years after procedure (WA cohort 1983-2009: incidence rate ratio, 0.70 [95% CI, 0.60-0.80]; WA and NSW cohort 2002-2010: incidence rate ratio, 0.63 [95% CI, 0.45-0.86]). Admissions for acute LRTI increased in the WA cohort and remained similar in the combined cohort. Admissions for epilepsy decreased 4 years after gastrostomy in the WA cohort and were generally lower in the combined cohort. Fundoplication seemed to decrease the relative incidence of acute LRTI admissions in the combined cohort. Conclusions Gastrostomy was associated with health benefits including reduced all-cause and epilepsy hospitalizations, but was not protective against acute LRTI. These decreases in hospitalizations may reflect improved delivery of nutrition and medications.

An increased prevalence of autism spectrum disorder (ASD) among children of immigrant backgrounds has been observed but clinical profiles are rarely compared. Diagnostic data from children with ASD notified to the Western Australian Register for Autism Spectrum Disorders were analysed according to maternal-race ethnicity and country of birth. A total of 4776 children aged between 0 and 18 years diagnosed with ASD from 1999 to 2017 were included. Those born to immigrant mothers from lower income countries were younger at the time of diagnosis, had an increased risk of intellectual disability and poorer presentations in the social and communication domains. Further work is required to understand environmental influences that may affect children born to immigrant mothers and to improve monitoring and assessments.

Objectives To evaluate the prevalence and risks of developmental disability (autism spectrum disorder, intellectual disability, and cerebral palsy) in Western Australian children of different groups of foreign-born women. Study design Western Australian population-based linked data of 764 749 singleton live births from 1980 to 2010 were used to compare disability outcomes among children of foreign-born, Australian-born non-Indigenous, and Indigenous women. The risk of disability was assessed using multinomial logistic regression. Results Overall, the prevalence of any disability was lowest for the children of foreign-born mothers. From 1980 to 1996 but not from 1997 to 2010, children born to mothers from foreign-born low-income countries had an increased relative risk of autism spectrum disorder with intellectual disability, and children born to foreign-born mothers from upper-middle-income countries had an increased risk of cerebral palsy with intellectual disability. After adjusting for smoking, the relative risks of intellectual disability and cerebral palsy with intellectual disability were markedly decreased in children of Australian-born Indigenous mothers. Conclusions Although we did not find among children born to foreign-born women an increased prevalence across all the measured developmental outcomes, we did observe an increased risk of autism spectrum disorder with intellectual disability and cerebral palsy with intellectual disability for mothers of some foreign-born groups. Our findings related to smoking in the Indigenous population underscore its possible role on the causal pathway to intellectual disability. Maternal migration is considered a factor on the causal pathway to intellectual disability. Maternal migration may be either a risk or a protective factor on the causal pathway to developmental disabilities and the direct role of migration is inconclusive in our study.

Background Few studies have examined the familial aggregation of melanoma or its co-aggregation with other cancers using whole-population based designs. This study aimed to investigate aggregation patterns in young Western Australian families, using population-based linked health data to identify individuals born in Western Australia between 1974 and 2007, their known relatives, and all incident cancer diagnoses within the resulting 1,506,961 individuals. Methods Cox proportional hazards regression models were used to compare the risk of melanoma for first-degree relatives of melanoma cases to that for first-degree relatives of controls, with bootstrapping used to account for correlations within families. The risk of (i) developing melanoma based on the number of first-degree relatives with other cancers, and (ii) developing non-melanoma cancers based on the number of first-degree relatives diagnosed with melanoma was also investigated. Results First-degree relatives of melanoma cases had a significantly greater incidence of melanoma than first-degree relatives of individuals not affected with melanoma (Hazard Ratio (HR) = 3.58, 95% bootstrap confidence interval (CI): 2.43–5.43). Sensitivity analyses produced a higher hazard ratio estimate when restricted to melanoma cases diagnosed before 40 years of age (HR = 3.77, bootstrap 95% CI: 2.49–6.39) and a lower estimate when only later-onset cases (>40 years) were considered (HR = 2.45, bootstrap 95% CI: 1.23–4.82). No significant evidence was found for co-aggregation between melanoma and any other cancers. Conclusions Results indicated a strong familial basis of melanoma, with the higher than expected hazard ratio observed likely to reflect early-age at onset cases in this young cohort, supported by the results of the sensitivity analyses. Exploratory analyses suggested that the determinants of melanoma causing the observed aggregation within families may be independent of other malignancies, although these analyses were limited by the young age of the sample. Determining familial aggregation patterns will provide valuable knowledge regarding improved clinical risk prediction and the underlying biological mechanisms of melanoma and other cancers.

Aim Mental health conditions and problems are often reported in children and adolescents with cerebral palsy (CP). A systematic review was undertaken to describe their prevalence. Method MEDLINE and PsycINFO databases from 1996 to 2016 were searched and reference lists of selected studies were reviewed. Studies were included if they reported point prevalence of mental health diagnoses or symptoms in a general population of children and/or adolescents with CP. Pooled prevalence for mental health symptoms was determined using a random effects meta-analysis. Results Of the 3158 studies identified, eight met the inclusion criteria. Mental health disorders were diagnosed by psychiatric interview in one study, giving a prevalence of 57% (32 out of 56 children). The remaining seven studies (n=1715 children) used parent-report mental health screening tools. The pooled prevalence for mental health symptoms using the Strengths and Difficulties Questionnaire (n=5 studies) was 35% (95% confidence interval [CI] 20–61) and using the Child Behavior Checklist (n=2 studies) was 28% (95% CI 22–36). Evidence was characterized by a moderate level of bias. Interpretation More studies are needed to ascertain the prevalence of mental health disorders. Mental health symptoms are common and mental health evaluations should be incorporated into multidisciplinary assessments for these children. What this paper adds Children with cerebral palsy and intellectual disability have a higher risk of mental health symptoms. The prevalence of mental health symptoms for age and severity groups is unclear.

In high income countries the life expectancy of people with Down syndrome (DS) rose significantly during the 20th century, from around nine years in 1949 to 57 years by 2000, equating to an increase of approximately 1 year of age per calendar year. This presentation quantifies survival patterns for people with DS using comprehensive population-based data collected over a 56-year period (1953–2009). All known persons diagnosed with DS were sourced from four complementary health and disability State-based databases (Disability Services, Death Registrations, Hospitalisations and Birth Defects Notifications) in Western Australia. Survival to 2010 was confirmed by the absence of a death registration between 1969 and 2010. Life expectancy was assessed using Kaplan Meier survival using the 1,948 cases born since 1953, which ensured that no death records were lost prior to the start of the earliest database. Deaths had occurred in 590 cases (25.3%). The results showed that survival rates started to decline between 55–60 years of age. Gender disparity was apparent, with females observed to have a slightly lower mean survival age than males throughout the lifespan. Although major improvements in the survival of children with DS are evident in recent decades, overall life expectancy appears to have plateaued with only minor increases in more recent years. The study findings suggest the possibility of a current natural upper survival limit for people with DS of around 60 years of age, and/or gaps in addressing health needs later in life through appropriate screening and early treatment.

Importance: The origins and development of autism spectrum disorder (ASD) remain unresolved. No individual-level study has provided estimates of additive genetic, maternal, and environmental effects in ASD across several countries.Objective: To estimate the additive genetic, maternal, and environmental effects in ASD.Design, Setting, and Participants: Population-based, multinational cohort study including full birth cohorts of children from Denmark, Finland, Sweden, Israel, and Western Australia born between January 1, 1998, and December 31, 2011, and followed up to age 16 years. Data were analyzed from September 23, 2016 through February 4, 2018.Main Outcomes and Measures: Across 5 countries, models were fitted to estimate variance components describing the total variance in risk for ASD occurrence owing to additive genetics, maternal, and shared and nonshared environmental effects.Results: The analytic sample included 2 001 631 individuals, of whom 1 027 546 (51.3%) were male. Among the entire sample, 22 156 were diagnosed with ASD. The median (95% CI) ASD heritability was 80.8% (73.2%-85.5%) for country-specific point estimates, ranging from 50.9% (25.1%-75.6%) (Finland) to 86.8% (69.8%-100.0%) (Israel). For the Nordic countries combined, heritability estimates ranged from 81.2% (73.9%-85.3%) to 82.7% (79.1%-86.0%). Maternal effect was estimated to range from 0.4% to 1.6%. Estimates of genetic, maternal, and environmental effects for autistic disorder were similar with ASD.Conclusions and Relevance: Based on population data from 5 countries, the heritability of ASD was estimated to be approximately 80%, indicating that the variation in ASD occurrence in the population is mostly owing to inherited genetic influences, with no support for contribution from maternal effects. The results suggest possible modest differences in the sources of ASD risk between countries.

Background Major increases in the survival of people with Down syndrome during the last two generations have resulted in extended periods of adulthood requiring specialist care, which in turn necessitates greater understanding of the nature, timing and impact of comorbidities associated with the disorder. Method The prevalence of five comorbidities reported as common in adults with Down syndrome, visual impairment, hearing impairment, epilepsy, thyroid disorders and dementia was assessed by decade of life. Results From early adulthood, people with Down syndrome are at enhanced risk of developing new comorbidities and they may present with multiple conditions. Three specific challenges are identified and discussed: are comorbidities detected in a timely manner, is the clinical progress of the disorder adequately understood, and who is responsible for the provision of care? Conclusions Further detailed investigations into the development and treatment of comorbidities across the lifespan are needed for a successful longitudinal approach to healthcare in people with Down syndrome. Implementation of this approach will better inform healthcare providers to ensure continuity of care with advancing age.

The increasing prevalence of Autism Spectrum Disorders (ASD) may in part be due to a shift in the diagnostic threshold that has led to individuals with a less severe behavioral phenotype receiving a clinical diagnosis. This study examined whether there were changes over time in the qualitative and quantitative phenotype of individuals who received the diagnosis of Autistic Disorder. Data were from a prospective register of new diagnoses in Western Australia (n = 1252). From 2000 to 2006, we examined differences in both the percentage of newly diagnosed cases that met each criterion as well as severity ratings of the behaviors observed (not met, partially met, mild/moderate and extreme). Linear regression determined there was a statistically significant reduction from 2000 to 2006 in the percentage of new diagnoses meeting two of 12 criteria. There was also a reduction across the study period in the proportion of new cases rated as having extreme severity on six criteria. There was a reduction in the proportion of individuals with three or more criteria rated as extreme from 2000 (16.0%) to 2006 (1.6%), while percentage of new cases with no "extreme" rating on any criteria increased from 58.5% to 86.6% across the same period. This study provides the first clear evidence of a reduction over time in the behavioral severity of individuals diagnosed with Autistic Disorder during a period of stability in diagnostic criteria. A shift toward diagnosing individuals with less severe behavioral symptoms may have contributed to the increasing prevalence of Autistic Disorder diagnoses. Autism Res 2017, 10: 179-187. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Background: It is well recognized that genetic disease makes a significant contribution to childhood illness. Here, we present recent population data describing the impact of single gene and chromosomal disorders on hospital admissions of children and adolescents. Methods: Hospital admissions for patients aged 0–19 years between 2000 and 2006, with a single gene or chromosomal disorder, were extracted from the Western Australian Hospital Morbidity Data System using 296 diagnosis codes identified from the International Statistical Classification of Diseases, Tenth Revision, Australian Modification. Data extracted for each patient included the number, length and cost of all admissions. Results: Between 2000 and 2006, 14,197 admissions were identified for 3,271 patients aged 0–19 years with single gene and chromosomal disorders, representing 2.6% of admissions and 4.3% of total hospital costs in this age group. Patients with genetic disorders had more admissions and stayed longer in hospital than patients admitted for any reason. Specific disorders associated with a high demand on hospital services included cystic fibrosis, Down syndrome, osteogenesis imperfecta, thalassemia, and von Willebrand’s disease. Conclusions: Children and adolescents with single gene and chromosomal disorders placed higher demands on hospital services than other patients in their age group, but were responsible for a relatively small proportion of hospital admissions and costs. These data will enable informed planning of health care services for patients with single gene and chromosomal disorders in Western Australia.

The etiology of autism spectrum disorders is unknown but there are claims of increasing prevalence in many countries. Despite more than a decade of epidemiological investigation, it is still unclear whether the rising trend in prevalence reflects a true increase or changes in diagnostic trends and improvements in case ascertainment. This paper discusses changes in diagnostic criteria, decreasing age at diagnosis, improved case ascertainment, diagnostic substitution, and social and cultural influences on the overall effects on prevalence, including the role of an ASD diagnosis as a gateway to funding. The evidence suggests that the increased prevalence of autism spectrum disorder can be partly supported by each of these factors, but remains largely unquantified due to a variety of other global and local factors. The question of how much of a real increase in prevalence has occurred remains crucially important to understand the classification, epidemiology and etiology of autism spectrum disorders but can only be answered if controlling these other factors.

Aim: To assess whether existing data collection mechanisms can provide accurate and sufficient information about the prevalence of autism in Australia. Methods: Summary data about the number of children aged 0–16 years known to have an autism spectrum disorder (ASD) were gathered from State and Territory health, disability, education sources and autism associations. Summary data were also provided by national sources. Initial contact was made by letter, and follow-up was undertaken by telephone or email. Results: For the years 2003–2004, the estimated prevalence of autism for 6- to 12-year-olds ranged from 9.6 to 40.8/10 000 for the State and Territory data, and from 12.1 to 35.7/10 000 for the national data. There was a similar variation in prevalence estimates for children aged 0–5 and 13–16 years. There was also a variation in prevalence estimates between age groups. Conclusion: Inconsistencies in autism prevalence estimates calculated from existing data sources suggest that further efforts are needed to ensure the collection of reliable information about the prevalence of ASD for national, State and Territory use. Existing data systems need to be improved or additional data systems need to be developed to ensure the collection of reliable information. Reliable and consistent ASD prevalence data would ensure that services are being provided to those who need them and would enhance the opportunities to undertake meaningful population-based research.

The Western Australian Family Connections Genealogical Project was proposed by Dr John Bass and implemented in 2003. The project aim is to create and store a system of links representing genealogical relationships for the residents of Western Australia (WA) to be used as a research tool in conjunction with health data to help investigate familial factors in health and disease. The project exists as a supplementary system of links to the WA Data Linkage System (WADLS) that regularly links records across several population-based data sets. When used in conjunction with this extensive collection of health-related data, the genealogical properties can enhance genetic and familial research projects to, for example, assess the degree of relatedness between individuals within study samples, assist in locating common ancestors and allow estimates of genetic risk. WA has developed particularly strong capabilities in the linkage of population-based data over the past three decades. Since 1995 it has supported a Data Linkage System, which has the primary aim of creating, storing and retrieving electronic links between records from core population-based systems, originating as early as 1966, and totalling nine data sets: birth, death and marriage registrations, electoral roll, hospital morbidity, emergency department presentations, mental health information, midwives notifications and cancers. Probabilistic matching techniques with extensive clerical review are used to identify records for the same individuals within and between the data sets. Dynamic updates of links for entries that relate to the same individuals are stored in a master links file. All links are created, stored and managed by the WADLS, but the detailed data remain the responsibility of the separate data custodians. The Family Connections project was initially funded by the Medical and Health Research Council of Western Australia, and additional funding to support staff has been received from the Telethon Institute for Child Health Research. Salary for the project manager is provided as a Team Investigator on a National Health and Medical Research Council Capacity Building Grant (#254545) awarded to The University of Western Australia. Approval for Phase I of the WA Family Connections project was given by the Human Research Ethics Committee of The University of Western Australia, and by the Confidentiality of Health Information Committee which reviews applications for access to confidential data at the Health Department of Western Australia.

Background Down syndrome is one of the commonest causes of intellectual disability. As life expectancy improves with early and more intensive surgical and medical treatments, people with the disorder are more likely to exhibit classic morbidity and mortality patterns and be diagnosed with diseases such as cancer. Methods A profile of cancer cases among people with Down syndrome has been compiled, based on the analysis of a linked data set that included information from the Disability Services Commission of Western Australian and the State Cancer Registry. Results and conclusions Although the total age- and sex-standardized incidence ratios (SIRs) for people with Down syndrome were similar to that for the general population, SIRs for leukaemia were significantly higher while the incidence of certain other types of cancers was reduced. Overall, there was a lower incidence of solid tumours in Down syndrome, possibly reflecting the age profile of the study cohort.

Background: Down syndrome (DS) affects ∼1 per 650-1000 live births and is the most common known genetic cause of intellectual disability. A highly significant change in the survival of people with DS has occurred during the last two generations, with life expectancy estimates increasing from 12 to nearly 60 years of age. Subjects and Methods: Detailed information on 1332 people in Western Australia with DS was abstracted from a specialist statewide database for the period 1953-2000 and electronically linked with three other state or national health and mortality data sources and the state Birth Defects Registry. Results: Over the last 25 years the percentage of women over 35 years giving birth increased from 4.8 to 18.6%, accompanied by an increase in the overall prevalence of DS from 1.1 to 2.9 per 1000 births. Four life stages of DS were identified: prenatal, childhood and early adulthood, adulthood, and senescence. Although pneumonia, or other types of respiratory infections, was the most common cause of death across the entire lifespan, ranging from 23% of deaths in adulthood to 40% in senescence, each life stage exhibited a particular profile of comorbidities. Congenital heart defects were common causes in childhood (13%) and adulthood (23%), whereas in senescence coronary artery disease (10%) and cardiac, renal, and respiratory failure (9%) were leading causes of mortality. Conclusions: A major re-appraisal in attitudes towards DS is required to ensure that the medical and social needs of people with the disorder are adequately met across their entire lifespan. In particular, specific recognition of the comorbidities that can arise at different ages is needed, accompanied by the provision of appropriate levels of care and management.

The social determinants of intellectual disability (ID) are poorly understood, particularly in Australia. This study has investigated sociodemographic correlates of ID of unknown cause in Western Australian born children. Using record linkage to the Western Australian Maternal & Child Health Research Database, maternal sociodemographic characteristics of children with ID (of unknown cause) born between 1983 and 1992 (n = 2871) were compared with those of children without ID (n = 236,964). Socioeconomic indices for areas based on the census district of mother's residence were also included in the analysis. Aboriginal mothers (OR = 2.83 [CI: 2.52, 3.18]), teenagers (OR = 2.09 [CI: 1.82, 2.40]) and single mothers (OR = 2.18 [CI: 1.97, 2.42]) were all at increased risk of having a child with mild or moderate ID. Children of mothers in the most socioeconomically disadvantaged 10% had more than five times the risk of mild and moderate ID compared with those in the least disadvantaged 10% (OR = 5.61 [CI: 4.42, 7.12]). Fourth or later born children were also at increased risk (OR = 1.82 [CI: 1.63, 2.02]). The results of the study have implications both for further aetiological investigation as well as service provision for children with ID. Furthermore, many of the sociodemographic correlates identified in this study, particularly in the mild/moderate category of ID, are potentially modifiable, opening up opportunities for primary prevention.

Cohort studies have indicated that the survival of individuals with Down's syndrome has dramatically increased over the past 50 years. Early childhood survival in particular has shown major improvement, due largely to advances in cardiac surgery and in general health management. The present study was based on a continuous cohort of 1332 people with Down's syndrome in Western Australia, registered for intellectual disability services between 1953 and 2000. Their life expectancy was 58.6 years, 25% lived to 62.9 years, and the oldest living person is 73 years of age. Life expectancy for males was greater than females by 3.3 years. The substantial increase in survival across the study period means that the life expectancy of people with Down's syndrome is approaching that of the general population, but accompanied by a range of significant mid-life health problems. The findings are of relevance to all developed countries and have considerable implications in terms of the counselling information provided to families at risk of having a child with Down's syndrome.

Autism is considered by many to be the most strongly genetically influenced multifactorial childhood psychiatric disorder. In the absence of any known gene or genes, the main support for this is derived from family and twin studies. Two recent studies (Greenberg et al. 2001; Betancur et al. 2002) suggested that the twinning process itself is an important risk factor in the development of autism. If true, this would have major consequences for the interpretation of twin studies. Both studies compared the number of affected twin pairs among affected sib pairs to expected values in two separate samples of multiplex families and reported a substantial and significant excess of twin pairs. Using data from our epidemiological study in Western Australia, we investigated the possibility of an increased rate of autism in twins. All children born between 1980 and 1995 with autism, Asperger syndrome, or pervasive developmental disorder not otherwise specified (PDD-NOS) were ascertained. Of the 465 children with a diagnosis, 14 were twin births (rate 30.0/1,000) compared to 9,640 children of multiple births out of a total of 386,637 births in Western Australia between 1980 and 1995 (twin rate weighted to number of children with autism or PDD per year 26.3/1,000). These data clearly do not support twinning as a substantial risk factor in the etiology of autism. We demonstrate that the high proportion of twins found in affected-sib-pair studies can be adequately explained by the high ratio of concordance rates in monozygotic (MZ) twins versus siblings and the distribution of family size in the population studied. Our results are in agreement with those of two similar studies by Croen et al. (2002) in California and Hultman et al. (2002) in Sweden.

To investigate using a Western Australian (WA) genealogical database for the identification of single gene and chromosome disorders among families.Hospital admissions for single gene and chromosome disorders recorded during 2000-2006 were identified from the WA Hospital Morbidity Data System. The proportion of these conditions occurring in family groups was then identified using genealogical links created through the WA Family Connections Genealogical Project.There were 216 family clusters among 11,303 people who were recorded as having a genetic or chromosomal disorder on their hospital admission record. The most common single gene conditions found to occur in multiple family members included blood clotting disorders such as Factor VIII deficiency and Von Willebrand's disease, followed by cystic fibrosis, myotonic dystrophies, neurofibromatosis, tuberous sclerosis, and osteogenesis imperfecta.Single gene disorders most commonly occurring in multiple family members have been identified using the WA Family Connections Genealogical Project. These disorders reflect the most common single gene disorders requiring hospital admission, but which are not fatal before reproductive age and do not result in a loss of fertility. They are also restricted to disorders with earlier onset, as the WA Family Connections Genealogical Project currently covers 2-3 of the most recent generations. This study demonstrates the utility of record linkage genealogies to identify kindred with genetic disorders, offering a rich resource of information for focused genetic epidemiological research.

Hand radiographs of 100 girls representing 73% of the known Australian population of girls with Rett syndrome, age 20 years or less, were available for this study. Control radiographs were matched for age, sex, and laterality. Bone age was assessed against standard radiographs in Greulich and Pyle [1959: Radiographic Atlas of Skeletal Development of the Hands and Wrist, 2nd ed.]. A metacarpophalangeal pattern (MCPP) profile comparing the relative lengths of the hand bones with mean population norms by age was produced by converting the length of each of the 19 metacarpal and phalangeal bones into a Z score. In girls less than 15 years old, bone age was more advanced in Rett syndrome than in age-matched control girls (left hand P = 0.03, right hand 0.004), but was most advanced in the younger group and normalized with age. In Rett syndrome, the mean Z score for the 19 metacarpal and phalangeal bones was 1.0 in children under 5 years, -0.27 in those aged 5-11 years, and -1.7 in those aged 12 years and over. This variation between age groups was much greater than in the controls. The dips in the MCPP profile occurred at MC2 and D1, and the peaks at M5, P5, and M4. An MCPP profile may provide an additional aid to diagnosis in cases of Rett syndrome where all the criteria are not met, but in children under age 5 years, advanced bone age may be more helpful as a marker.

Objectives To describe the hospitalisation patterns in children with intellectual disability (ID) and/or autism spectrum disorder (ASD) after the first year of life and compare with those unaffected. Design Prospective cohort study using data linkage between health, ID and hospitalisation population-based datasets. Setting Western Australia. Participants 416 611 individuals born between 1983 and 1999 involving 1 027 962 hospital admission records. Five case categories were defined (mild/moderate ID, severe ID, biomedically caused ID, ASD with ID and ASD without ID) and compared with the remainder of children and young people. Primary and secondary outcome measures Time to event analysis was used to compare time hospitalisation and rate of hospitalisation between the different case-groups by estimating HR, accounting for birth year and preterm birth status. Results ID and/or ASD were found to be associated with an increased risk of hospitalisation compared with the remainder of the population. The increase in risk was highest in those with severe ID and no ASD (HR=10.33, 95% CI 8.66 to 12.31). For those with ID of known biomedical cause or mild ID of unknown cause, the risk of hospitalisation was lower (HR=7.36, 95% CI 6.73 to 8.07 and HR=3.08, 95% CI 2.78 to 3.40, respectively). Those with ASDs had slightly increased risk (HR=2.82, 95% CI 2.26 to 3.50 for those with ID and HR=2.09, 95% CI 1.85 to 2.36 for those without ID). Conclusions Children with an ID or ASD experience an increased risk of hospitalisation after the first year of life which varied from 2 to 10 times that of the rest of the population. Findings can inform service planning or resource allocation for these children with special needs.

Data linkage is the bringing together of specific datasets from different sources using demographic information on individuals within a population. In Western Australia, systematic record linkages between multiple datasets including births, deaths, and hospital morbidity have occurred since 1997. Linkage to other population datasets related to intellectual disability and autism provides an infrastructure to undertake research in this area. The purpose of this chapter is to use the Western Australian experience to describe the potential of data linkage to improve the understanding of the epidemiology of intellectual disability and autism. Information is provided on the core datasets and specific disability registers available in Western Australia. Some recently developed novel initiatives are also described. One of these involves the linkage of data from a number of other Western Australian jurisdictions such as education, child protection, and justice in addition to health. The other uses a federated approach, developed by the bioinformatics team at the Telethon Institute for Child Health Research, to enable analysis of autism risk factors from international population-based datasets without the data leaving its home base. Examples of published research examining both determinants and outcomes of intellectual disability and autism are reported as well as information on several studies, which are in the planning stages. We also include a section on some of the challenges of data management and describe some of the statistical techniques that have been used. Studies investigating sociodemographic factors, prenatal growth, alcohol exposure, and maternal physical health have identified risk factors associated with intellectual disability and autism. Analyses of outcomes for these children have shown an increased risk of hospitalizations from two to ten times that of the rest of the population. For those with Down syndrome, a quarter of their admissions occurred in the first year of life, with upper respiratory tract infections being the most common cause. Non-Aboriginal children with intellectual disability were shown to have a threefold risk of substantiated child maltreatment and Aboriginal children a twofold risk, after taking parental factors into account. Linked data studies using population data on intellectual disability and autism can help understand the complex multidimensional factors contributing to different outcomes for this particularly vulnerable and underresearched population and provide valuable information for informing policies and programs.

Objective To calculate the survival of people with Down syndrome over the past 60 years and the influence of major perinatal factors by using linked population-based data. Study design A data linkage between 2 Western Australian (WA) data sets (the Register for Developmental Anomalies and the Intellectual Disability Exploring Answers database) was used to identify 772 children born with Down syndrome in WA from 1980-2010. Perinatal and mortality data were extracted from the WA Midwives Information System and WA death registrations and compared with the remaining WA population born during that same era. An additional 606 children with Down syndrome living in WA prior to 1980 were available from a disability services database and were used for predicting survival into adulthood. Results Overall, for cases born 1953-2010, 88% (95% CI 86%, 90%) survived to 5 years of age, 87% (95% CI 85%, 89%) to 10 years, and 83% (95% CI 80%, 85%) to 30 years. Children live-born with Down syndrome were significantly more likely (all P > .001) to have mothers older than 35 years (32.7% vs 13.4%), a gestational age less than 37 weeks (23.8% vs 7.9%), a cesarean delivery (28.9% vs 23.0%), and a birth weight less than 2500 g (20.4% vs 6.1%). Down syndrome survival was reduced in the presence of a cardiovascular defect, younger gestational age, low birth weight, or earlier birth years. Conclusions Improved survival for children born with Down syndrome over the last 60 years has occurred incrementally, but disparities still exist for children who are preterm or have low birth weight.

BackgroundAs well as being highly comorbid conditions, autism spectrum disorders (ASD) and intellectual disability (ID) share a number of clinically-relevant phenomena. This raises questions about similarities and overlap in diagnosis and aetiological pathways that may exist for both conditions.AimsTo examine maternal conditions and perinatal factors for children diagnosed with an ASD, with or without ID, and children with ID of unknown cause, compared with unaffected children.MethodsThe study population comprised all live singleton births in Western Australia (WA) between January 1984 and December 1999 (N = 383,153). Univariate and multivariate multinomial logistic regression models were applied using a blocked modelling approach to assess the effect of maternal conditions, sociodemographic factors, labour and delivery characteristics and neonatal outcomes.ResultsIn univariate analyses mild-moderate ID was associated with pregnancy hypertension, asthma, urinary tract infection, some types of ante-partum haemorrhage, any type of preterm birth, elective C-sections, breech presentation, poor fetal growth and need for resuscitation at birth, with all factors showing an increased risk. Severe ID was positively associated with poor fetal growth and need for resuscitation, as well as any labour or delivery complication. In the multivariate analysis no maternal conditions or perinatal factors were associated with an increased risk of ASD without ID. However, pregnancy hypertension and small head circumference were associated with a reduced risk (OR = 0.64, 95% CI: 0.43, 0.94; OR = 0.58, 95% CI: 0.34, 0.96, respectively). For ASD with ID, threatened abortion before 20 weeks gestation and poor fetal growth were associated with an increased risk.ConclusionFindings show that indicators of a poor intrauterine environment are associated with an elevated risk of ID, while for ASD, and particularly ASD without ID, the associations are much weaker. As such, these findings highlight the importance of accounting for the absence or presence of ID when examining ASD, if we are to improve our understanding of the causal pathways associated with these conditions.

Background. To date, relatively few representative data have been available to health planners and advocacy groups on the life expectancy of people with intellectual disability. A study of trends in the survival profiles of people with intellectual disability was undertaken to assist in the planning of appropriate medical and support services. Methods. Since 1953, the Disability Services Commission of Western Australia has maintained a database of persons diagnosed with intellectual disability. The database was used to calculate survival probabilities on a total of 8724 individuals, 7562 of whom were still alive at the time of sampling in December 2000. Results. Kaplan-Meier survival plots showed a strong negative association between severity of intellectual disability and survival, with median life expectancies of 74.0, 67.6, and 58.6 years for people with mild, moderate, and severe levels of handicap. Significant negative associations also were observed with male gender, Indigenous Australian parentage, and individuals diagnosed with a specific genetic disorder. Conclusions. The findings indicate a major and expanding increase in the service requirements of this aging, intellectually disabled population during the past two generations.

Prevalence statistics for autism spectrum disorders (ASD) vary widely across geographical boundaries. Some variation can be explained by diagnostic methods, case ascertainment and age at diagnosis. This study compared prevalence statistics for two distinct geographical regions, Denmark and Western Australia, both of which have had population-based registers and consistent classification systems operating over the past decade. Overall ASD prevalence rates were higher in Denmark (68.5 per 10,000 children) compared with Western Australia (51.0 per 10,000 children), while the diagnosis of childhood autism was more prevalent in Western Australia (39.3 per 10,000 children) compared with Denmark (21.8 per 10,000 children). These differences are probably caused by local phenomena affecting case ascertainment but influence from biological or geographical factors may exist.

BACKGROUND It is unclear whether the increase in autism over the past two decades is a real increase or due to changes in diagnosis and ascertainment of autism spectrum disorders (ASDs), which include autism, Asperger syndrome and pervasive developmental disorder not otherwise specified (PDD-NOS). The aim of this study was to examine the trends in ASD over time in Western Australia (WA) and the possible effects and contribution of changes in diagnostic criteria, age at diagnosis, eligibility for service provision based on ASD diagnoses and changes in diagnostic practices. METHODS A population-based study was conducted among the cohort of children born in WA between 1983 and 1999 and diagnosed with ASD between the age of 2 and 8 years up to December 31, 2004. The trend in ASD diagnosis over the study period was assessed by investigating birth cohort and period effects, and examining whether these were modified by age of diagnosis. ASD diagnosis corresponding with changes in diagnostic criteria, funding and service provision over time were also investigated. A subgroup analysis of children aged