Brief Report: Gender and Age of Diagnosis Time Trends in Children with Autism Using Australian Medicare Data.
Australian Medicare data show the autism gender gap is shrinking among school-age children, implying earlier under-recognition of girls.
01Research in Context
What this study did
May et al. (2018) looked at every autism bill paid by Australian Medicare from 2004-2017.
They counted new diagnoses and split them by sex and age. No kids were tested in person; the data came from insurance records.
What they found
Autism numbers kept rising.
The big news: among 5- to 12-year-olds, the boy-to-girl ratio got smaller. More older girls are now being picked up, suggesting earlier under-counting of females.
How this fits with other research
Baker (2002) saw the same ratio shrink in one Australian region a decade earlier, so the trend is steady.
Rutherford et al. (2016) and Gu et al. (2023) also show girls get diagnosed later than boys, matching the Medicare pattern.
Lai et al. (2012) in Taiwan and Gal et al. (2012) in Israel found rising autism rates too, proving the climb is global.
Why it matters
If you assess school-age kids, know that girls can slip through. Add sex-aware questions to your intake forms and watch for subtle social signs. Earlier identification means earlier intervention, and that can change a girl’s entire school experience.
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02At a glance
03Original abstract
Recent evidence suggests the male predominance in Autism Spectrum Disorder (ASD) may be decreasing. Secondary analyses of Australian Medicare data (paediatrician/child psychiatrist items for diagnosing ASD before age 13) were used (N = 73,463 unique children from 1-July-2008 to 30-June-2016). Cumulative incidence of ASD in 4-year-olds in 2015/2016 was 1.10% [95% CI 1.06-1.14], males 1.66% [95% CI 1.60-1.72] and females 0.51% [95% CI 0.47-0.55]. New diagnoses significantly increased in older (5-12 years) males and females but not younger (0-4 years) children, from 2010/2011 to 2015/2016. The M:F ratio decreased in older children (4.1-3.0), but not significantly in younger children (4.2-3.5). Identification of older males and females is contributing to the increased in ASD in Australia and proportionally more older females are being diagnosed.
Journal of autism and developmental disorders, 2018 · doi:10.1007/s10803-018-3609-7