To the best of our knowledge, this is the most comprehensive and recent attempt to estimate the prevalence of various types of childhood neurodisabilities in a disadvantaged geographical region in Australia, using readily available data sources. Our analysis suggests that there is a greater proportion of children with disabilities in SWS compared to the rest of the state and that ASD is the most common neurodisability presenting to public developmental services. According to the most recent data on people with a disability from the ABS, the prevalence of any developmental disability in Australia increased from 6.9–7.42% between 2009 and 2015; but this did not specify the types of childhood disabling conditions.31 We know child disability is common, but robust current estimates to inform planning and service provision are entirely lacking. Available data sources were incomplete and inadequate. Nevertheless, our analysis points to potential inequity in the access to disability support for children with neurodisability in SWS.
SWS as a region has been reported to have the highest number of communities in the lowest decile as per the Index of Relative Socio-economic Advantage and Disadvantage (IRSAD),32 and the fifth most socially disadvantaged region in Australia.32 The region also has the highest refugee intake in the state of NSW, a high culturally and linguistically diverse population, 33 all of which may contribute to the current increased proportion of children with disability. In their systematic review of the association between disabling conditions in childhood and socio-economic disadvantage, Spencer et al (2015) concluded that there was a strong association in high income countries between childhood disability and social disadvantage, with risk estimates being highest for intellectual disability.13 Australian data on childhood disability confirms this finding, with higher representation of children with severe disability among low-income households.32 Similarly, analysis of disability data from the United Kingdom points to children with disability being more likely to live with low-income, deprivation, debt and poor housing.8 On the other hand, while the majority of children with a disability live in low/middle income countries and despite socially and biologically plausible mechanisms underlying the association of low socio-economic status with childhood disability, empirical evidence from quantitative studies is inconsistent and contradictory.34
We focused on the best possible diagnostic specific data sources that enumerated children with disabilities in SWS and NSW. National levels data sets such as Australian Early Development Census (AEDC) or the ABS datasets are limited in exploring regional inequities in childhood disabilities as they enumerate proportions of children with disabilities at the state and national level.35 36 These datasets can hide regional urban health and social inequalities.37 We also focused specifically on neurodisability and conditions that were most relevant from the clinical and health service delivery perspectives: ASD, GDD, CP, Intellectual Disability, and sensory impairments including hearing and vision impairment. These diagnostic groups align with the intellectual and sensory/speech impairments from the 2015 Survey of Disability, Ageing and Carers (SDAC) conducted by Australian Bureau of Statistics, 36 38 and the five core development domains used by AEDC Census. 35
While there is a range of developmental assessment services that exist for children in SWS region and NSW, including private paediatric and psychology clinics, the information from the CDAS database represented the caseload of children seen with a disability presenting to a public developmental diagnostic service. In SWS, approximately two-thirds of children in the developmental assessment services were diagnosed with ASD or ASD with GDD. This information correlates with the increasing prevalence of ASD globally, partly due to the changes in the diagnostic criteria for ASD in the 5th edition of the Diagnostic and Statistical Manual (DSM-V).10 Other reasons hypothesised for the increase in ASD prevalence are a greater awareness of this condition, diagnosis at earlier ages, and the recognition that ASD is a life-long condition that requires ongoing support.39A survey of Australian paediatricians also report that they diagnose ASD in 39–56% of children in their first ambulatory consultation.40 We cannot provide population estimates of ASD and GDD based on this data source, but it indicates the burden of neurodisability conditions requiring diagnostic assessment at a district level.
In the CDAS data, 60% of children were of a CALD background; these children had an increased risk of having global developmental delay. Previous qualitative research in Sydney has shown that children from CALD backgrounds with developmental problems miss out both on developmental surveillance and early intervention, highlighting the need for increased resource allocation for appropriate care and public awareness.41 A similar analysis of a child development service in a defined geography in the United Kingdom, found that children from Pakistani cultural background showed a higher prevalence than other groups of severe disability and severe visual and hearing impairments.42 Children of Aboriginal background represented 6% of children seen at CDAS, which is three times above the population of Aboriginal children in SWS.43 While there is limited quantitative data on children with disability in Aboriginal populations, there is evidence from SWS that, even in the urban setting, Aboriginal children are at greater risk of developmental disability compared to non-Aboriginal children.44 45 Given the postulated excess burden of childhood disability in Aboriginal populations, there is limited published literature or robust data in Australia on any conditions apart from hearing loss and learning disabilities consequent of otitis media.46 Other public clinical services for vulnerable children and youth in SWS also document high levels of developmental disability, such as over 40% of the refugee clinic cohort,26 and over a quarter of Aboriginal children in foster care.47
The prevalence of CP in SWS (1.86/1000) is similar to the rest of the NSW population. However, there was an increased severity of functional and intellectual impairment in the children with CP in SWS. Our findings concur with a recent Australian study describing an increased risk of non-ambulatory status, moderate-to-severe intellectual impairment and presence of severe comorbidities in individuals with CP born in low socioeconomic status neighbourhoods like SWS.48 It is likely that there is under ascertainment even with this register, as there may be newly arriving children of migrant and refugee background who do not get a timely diagnosis of cerebral palsy. Further research is needed to explore the factors influencing the increased likelihood of severe functional impairment in CP in such vulnerable populations, as well as mechanisms to enhance access to their essential health care needs.
Data from the RIDBC showed that in SWS there was increasing severity of visual impairment compared to NSW. RIDBC data has under ascertainment, as parents self-select to register their children on the RIDB registry. Newborn hearing screening on the other hand is almost complete and very accurately represents population prevalence. While we do not have contemporaneous data to compare with the rest of the state, the rate of neonatal SHL is similar in SWS to the global prevalence of this condition.49
Using Department of Education data for children with disabilities requiring supports, we found that the proportion of children with intellectual delay and ASD accessing supported education were significantly higher in SWS than the rest of NSW. We noted that SWS had disproportionately fewer classes for physical disability and sensory impairments than the rest of NSW. This is despite higher burden of functional impairments for children with CP and visual impairment in SWS, indicating potential inequity in the level of specialist educational supports provided in this region.
Data from NDIS indicates that there is a slight increase in proportion of children accessing disability supports for intellectual disability, but all other conditions were on par with SWS population. This suggests that significant numbers of children with neurodisability in SWS are not accessing NDIS. A linked dataset between a state-wide register and NDIS participants is needed to accurately ascertain this and we, therefore, argue for a state-wide disability register that links with NDIS datasets as well as with the National Disability Data Asset.50