The Western Australian register for autism spectrum disorders

Quality of life beyond diagnosis in intellectual disability - Latent profiling

OBJECTIVE

To compare quality of life (QOL) across diagnoses associated with intellectual disability, construct QOL profiles and evaluate membership by diagnostic group, function and comorbidities.

METHOD

Primary caregivers of 526 children with intellectual disability (age 5-18 years) and a diagnosis of cerebral palsy, autism spectrum disorder, Down syndrome, CDKL5 deficiency disorder or Rett syndrome completed the Quality of Life Inventory-Disability (QI-Disability) questionnaire. Latent profile analysis of the QI-Disability domain scores was conducted.

RESULTS

The mean (SD) total QOL score was 67.8 (13.4), ranging from 60.3 (14.6) for CDD to 77.5 (11.7) for Down syndrome. Three classes describing domain scores were identified: Class 1 was characterised by higher domain scores overall but poorer negative emotions scores; Class 2 by average to high scores for most domains but low independence scores; and Class 3 was characterised by low positive emotions, social interaction, and leisure and the outdoors scores, and extremely low independence scores. The majority of individuals with autism spectrum disorder and Down syndrome belonged to Class 1 and the majority with CDKL5 deficiency disorder belonged to Class 3. Those with better functional abilities (verbal communication and independent walking were predominately members of Class 1 and those with frequent seizures were more often members of Class 2 and 3.

CONCLUSION

The profiles illustrated variation in QOL across a diverse group of children. QOL evaluations illustrate areas where interventions could improve QOL and provide advice to families as to where efforts may be best directed.

Comorbidities and quality of life in children with intellectual disability

BACKGROUND

Many children with intellectual disability live with medical comorbidities. This study examined the impacts of comorbidities on quality of life (QOL) of children with intellectual disabilities and whether impacts varied with caregiver perceptions that medical needs had been met.

METHODS

Primary caregivers of 447 children (aged 5-19 years) with an intellectual disability reported on their child's medical comorbidities and the extent to which they perceived their child's medical needs had been met in a cross-sectional observational study. The Quality of Life Inventory-Disability was used to measure QOL on a 100-point scale. Linear regression models including interaction terms were used to evaluate their associations.

RESULTS

Parent-reported recurrent child pain (-4.97, 95% CI -8.21, -1.72), night-time sleep disturbances (-4.98, 95% CI -7.23, -2.73), daytime somnolence (-8.71, 95% CI -11.30, -2.73), seizures that occurred at least weekly (-7.59, 95% CI -13.50, -1.68) and conservatively managed severe scoliosis (-7.39, 95% CI -12.97, -1.81) were negatively associated with child QOL. Despite the majority of parents (~70%) perceiving that their child's medical needs had been met to a great extent, this did not significantly moderate the association between any comorbidities and QOL.

CONCLUSIONS

Comorbidities were common and had marked associations with QOL. Evaluation and management of pain and sleep disturbance continue to be high priorities in improving QOL of young people with intellectual disabilities. Further research on the optimal methods of managing these comorbidities is warranted.

Investigating associations between birth order and autism diagnostic phenotypes

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.

Determinants of sleep problems in children with intellectual disability

Children with intellectual disabilities are more likely to experience sleep disorders of insomnia, excessive daytime sleepiness and sleep breathing disorders than typically developing children. The present study examined risk factors for these sleep disorders in 447 children (aged 5-18 years), diagnosed with an intellectual disability and comorbid autism spectrum disorder, cerebral palsy, Down syndrome or Rett syndrome. Primary caregivers reported on their child's sleep using the Sleep Disturbance Scale for Children (SDSC), as well as medical comorbidities and functional abilities. Multivariate linear and logistic regressions were used to examine the effects of these factors on SDSC t scores and a binary indicator, respectively for the relevant subscales. Receiving operating characteristic curves were generated for each logistic regression model to determine their ability to discriminate between poor and good sleep. Comorbidities rather than functional abilities were associated with poorer sleep. In particular, recurrent pain, frequent seizures, frequent coughing, constipation and prescription of sleep medications were associated with abnormal sleep across the entire sample, but predictors differed between diagnostic groups. The present study suggests that comorbidities are more strongly associated with quality of sleep than functional impairments. The present study provides new information on potential associations between frequent coughing, prescription sleep medications and sleep quality that should be further investigated.

Functioning, participation, and quality of life in children with intellectual disability: an observational study

AIMS

To investigate associations between functioning, community participation, and quality of life (QoL) and identify whether participation mediates the effects of functioning on QoL.

METHOD

The caregivers of 435 children (211 females, 224 males; mean age 12y; SD 3y 11mo; age range 5-18y) with intellectual disability and autism spectrum disorder, cerebral palsy, Down syndrome, or Rett syndrome reported on their child's functioning (dependence for managing personal needs, mobility, communication, eye contact when speaking), frequency of participation, and QoL. Linear regression and mediation analyses were used to evaluate the relationships between child functioning, participation, and QoL.

RESULTS

Children with greater dependency for managing personal needs and limited eye contact when speaking experienced poorer QoL. Less impaired functioning was associated with more frequent participation, which, in turn, was associated with a 3-point gain in QoL for each additional point in frequency of participation (coefficient=2.67, 95% confidence interval 1.56-3.78). The effect of impaired functioning on QoL was partially mediated by participation in children with greater dependency in managing personal needs and those with mildly impaired communication.

INTERPRETATION

Greater levels of impairments with poorer functioning, notably a high level of dependence, were associated with poorer QoL. Poorer QoL can be partly explained by less frequent community participation.

Deconstructing the repetitive behaviour phenotype in autism spectrum disorder through a large population-based analysis

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.

The misnomer of ‘high functioning autism’: Intelligence is an imprecise predictor of functional abilities at diagnosis

‘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.

A comparison of autism prevalence trends in Denmark and Western Australia

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.

The validity of psychiatric diagnoses: the case of 'specific' developmental disorders

We tested whether developmental coordination disorder (DCD) and mixed receptive expressive language disorder (RELD) are valid diagnoses by assessing whether they are separated from each other, from other childhood disorders, and from normality by natural boundaries termed zones of rarity. Standardized measures of intelligence, language, motor skills, social cognition, and executive functioning were administered to children with DCD (n = 22), RELD (n = 30), autistic disorder (n = 30), mental retardation (n = 24), attention deficit/hyperactivity disorder (n = 53) and to a representative sample of children (n = 449). Discriminant function scores were used to test whether there were zones of rarity between the DCD, RELD, and other groups. DCD and RELD were reliably distinguishable only from the mental retardation group. Cluster and latent class analyses both resulted in only two clusters or classes being identified, one consisting mainly of typical children and the other of children with a disorder. Fifty percent of children in the DCD group and 20% in the RELD group were clustered with typical children. There was no evidence of zones of rarity between disorders. Rather, with the exception of mental retardation, the results imply there are no natural boundaries between disorders or between disorders and normality.

Autism spectrum disorders in young children: effect of changes in diagnostic practices

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 <or=5 years was also conducted to examine trends in the incidence and age of diagnosis of ASD and intellectual disability (ID) and to investigate the role of changes in diagnostic practices.

RESULTS

The overall prevalence of ASD among children born between 1983 and 1999 and diagnosed by age 8 was 30 per 10,000 births with the prevalence of autism comprising 21 per 10,000 births. The prevalence of ASD increased by 11.9% per annum, from 8 cases per 10,000 births in 1983 to 46 cases per 10,000 births in 1999. The annual incidence of ASD, based on newly diagnosed ASD cases in each year from 1985 to 2002, increased over the study period. The increase in incidence of ASD appeared to coincide with changes in diagnostic criteria and availability of funding and services in WA, particularly for children aged <5 years. The age-specific rates of autism and PDD-NOS increased over time and the median age of diagnosis for autism decreased from 4 to 3 years of age throughout the 1990s. For children aged <or=5 years the incidence of ASD diagnosis increased significantly from 1992, with an average annual increase of 22%. Similar findings were found for autism. In the corresponding years the incidence of diagnosis of severe ID fell by 10% per annum and mild-moderate ID increased by 3% per annum.

CONCLUSIONS

The rise in incidence of all types of ASDs by year of diagnosis appears to be related to changes in diagnostic and service provision practices in WA. In children aged <or=5 years, diagnosis of severe ID decreased, but mild-moderate ID increased during the study period. A true increase in ASD cannot be ruled out.

The prevalence of autism in Australia. Can it be established from existing data?

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.

Management of assessments and diagnoses for children with autism spectrum disorders: the Western Australian model

Autism spectrum disorders (ASDs) are severe developmental conditions that require specialised intervention and lifelong support. Recent increases in ASD prevalence have prompted new initiatives in Western Australia to improve the consistency of assessments and to more accurately monitor diagnostic trends within the population. WA has implemented statewide guidelines for the assessment of ASDs, has developed an open forum for clinicians to discuss issues relating to the assessment process, and supports a statewide register of newly diagnosed cases. These initiatives have led to improved consistency across assessments, allowed analysis of diagnoses over time, and promoted cohesiveness among autism assessors. These strategies potentially provide an alternative model for other states and territories that wish to strengthen and assimilate ASD assessments.

Estimating the Burden of Disease for Autism Spectrum Disorders in Spain in 2003

Autism Spectrum Disorders (ASD) are lifelong neurodevelopmental disabilities. Burden of Disease is an indicator that provides important information on health status and outcomes such as premature mortality and disability. In order to estimate the burden of disease of ASD in the Spanish population during 2003, we followed the procedures used in the WHO Global Burden of Disease Study. ASD generated 43,928 Disability Adjusted Life Years (DALY) in Spain in 2003, from which 33,797 were attributable to Autistic Disorder and 10,131 were caused by Asperger's Disorder and Pervasive Developmental Disorder-Not Otherwise Specified. DALY could be a useful tool for health policy makers for setting health service priorities, allocating available resources effectively and providing a comparable measure of output for early intervention.

Are abilities abnormally interdependent in children with autism?

We propose that stronger than usual correlations between abilities indicate which cognitive processes are impaired in autism. Study 1 compared partial correlations (controlling age) between intelligence and social cognition in children with autism (n = 18), mental retardation (MR; n = 34), or no psychological disorder (n = 37). Correlations were stronger in the autism group. Study 2 compared correlations between measures of perceptual organization and verbal comprehension, receptive and expressive language, fine and gross motor coordination, and theory of mind, emotion recognition, and emotion understanding abilities in children with autism (n = 30) or MR (n = 24) and in a large representative sample of children (n = 449). Results indicate that autism is marked by stronger correlations between all ability domains, and MR is marked by stronger correlations between motor coordination tasks and other ability measures.

Autism following a history of newborn encephalopathy: more than a coincidence?

Between June 1993 and December 1996, 276 term newborn infants with encephalopathy and 564 randomly selected term controls were enrolled in a population-based study of moderate and severe term newborn encephalopathy (NE) in Western Australia. During comprehensive neurobehavioural and cognitive follow-up of all patients and controls at 3 years and again at 5 years of age we found an unexpected but strong association between NE and autism spectrum disorders (ASDs). A diagnosis of ASD by age 5 years was reached using criteria according of the Diagnostic Statistical Manual, 4th edition. Linking records to the Western Australian Disability Services Commission Register ensured that no child in the study with ASD was missed. By age 5 years, 37 (13.4%) infants with NE and one (0.2%) control had died. Among the 239 survivors of NE, 12 (5%) were diagnosed with an ASD. Of these, 10 (4.2%) met the full criteria for autism, one had pervasive developmental disorder-not otherwise specified, and one had Asperger syndrome. Among the 563 surviving controls, five (0.8%) were diagnosed with an ASD: three with autism, one with autism/possible Asperger syndrome, and one with Asperger syndrome. Compared with the controls, the children who had experienced NE were 5.9 times (95% confidence interval 2.0-16.9) more likely to have been diagnosed with an ASD.

Incidence of autism spectrum disorders in children in two Australian states

AIM

To ascertain the incidence of autism spectrum disorders in Australian children.

SETTING

New South Wales (NSW) and Western Australia (WA), July 1999 to December 2000.

DESIGN

Data were obtained for WA from a prospective register and for NSW by active surveillance.

MAIN OUTCOME MEASURES

Newly recognised cases of autism spectrum disorders (defined as autistic disorder, Asperger disorder and pervasive developmental disorder not otherwise specified [PDD-NOS]) in children aged 0-14 years; incidence was estimated in 5-year age bands (0-4 years, 5-9 years, 10-14 years).

RESULTS

In WA, 252 children aged 0-14 years were identified with autism spectrum disorder (169 with autistic disorder and 83 with Asperger disorder or PDD-NOS). Comparable figures in NSW were 532, 400 and 132, respectively. Most children were recognised with autistic disorder before school age (median age, 4 years in WA and 3 years in NSW). Incidence of autistic disorder in the 0-4-years age group was 5.5 per 10,000 in WA (95% CI, 4.5-6.7) and 4.3 per 10,000 in NSW (95% CI, 3.8-4.8). Incidence was lower in older age groups. The ratio of all autism spectrum disorders to autistic disorder alone was 1.5:1 in WA and 1.3:1 in NSW, and rose with age (1.8:1 and 2.9:1 in 10-14-year-olds in WA and NSW, respectively).

CONCLUSIONS

These are the first reported incidence rates for autism for a large Australian population and are similar to rates reported from the United Kingdom. Ongoing information gathering in WA and repeat active surveillance in NSW will help to monitor any future changes.

Childhood autism spectrum disorder in the Barwon region: a community based study

OBJECTIVE

To establish a community database for children with autism spectrum disorder (ASD) to determine prevalence and identify subgroups based on key intellectual, clinical and family parameters.

METHODS

Data were collected for children previously diagnosed with an ASD in the Barwon region using parental interview and review of the child's paediatric and psychological records. Preschool diagnoses were typically made by specialist psychologists and school-age diagnoses made by a multidisciplinary team.

RESULTS

One hundred and seventy-seven children in the Barwon region were identified as having ASD (82% response rate). The prevalence of ASD was one per 255 children aged two to 17 years. The prevalence increased 10 fold over a 16-year period and this increase was relatively even across all levels of child intellectual functioning. Forty-two percent of children were intellectually disabled (IQ < 70) and performance IQ was significantly higher than verbal IQ but typical block design-comprehension subtest patterns were not common. Nine sibling pair families were identified, 24% were labelled as having attention deficit hyperactivity disorder (ADHD), 6% had epilepsy, and 18.3% were macrocephalic where data were available. Family difficulty was associated with the degree of obsessions/rituals, frequency and intensity of anger/aggression, and ADHD but overall was not associated with the child's intellectual status.

CONCLUSIONS

The relatively rapid increase in prevalence is consistent with overseas studies and suggests significant changes in diagnostic criteria, increasing community awareness and the need for support at all levels of intellectual functioning. Increased occurrence in siblings and relatives gives further evidence for a genetic cause.