Trends in the growth of autism spectrum disorder (ASD) cases are inconsistent worldwide, according to research by GlobalData, with countries such as the US seeing an increase in cases, while Japan and countries in Europe experience negative growth. The leading data and analytics company notes that this fluctuation may be due to a lack of consistent diagnostic criteria between countries, alongside changing population structures.

ASD, or autism, refers to a range of common neurodevelopmental conditions characterized by social and communication challenges and pervasive repetitive behaviors.

Inconsistent ASD diagnostic criteria one factor in global case growth variation

According to GlobalData’s latest report, ‘Autism Spectrum Disorder: Epidemiology Forecast to 2031’, the US is expected to see a 0.3% growth rate in ASD cases, reaching 3.3 million cases, while countries in the 5EU** and Japan are seeing negative growth (-1.4% in Japan and growths in Europe ranging from -0.2% in France to 1.2% in Spain). These differences in ASD growth rates worldwide indicate some deeper, underlying issues. One factor is likely a lack of consistent diagnosis criteria.

 Anna Moody, MRES, Epidemiologist at GlobalData, comments: “Most countries predominantly use the DSM-5 criteria, which was introduced in 2013. However, others have taken longer to enforce this new criterion and are currently using both ICD-10 (first published in 1994) and DSM-5. As ASD is renowned for its heterogeneous nature, it is important that there is a universal diagnostic criterion so that prevalence estimates are completely comparable. Considering the significant psychological and social burden that ASD has on individuals and their families, it is essential that governments and health practitioners understand the symptoms associated with the disorder and can make correct diagnoses so that individuals can seek the appropriate care.”

Clearer treatment guidelines and diagnosis challenges two key unmet needs

However, it is not just the diagnosis criteria that could use clarity and consistency. Earlier research by GlobalData*** revealed that clearer treatment guidelines and challenges in diagnosis were important unmet clinical needs for ASD.

Pippa Salter, Pharma Analyst at GlobalData, comments: “With a lack of approved therapies for ASD there is an unmet need for the development of clearer guidelines surrounding the use of off-label pharmacological treatments for managing ASD. Clearer guidelines could also incentivize earlier diagnosis by providing a clear strategy of how the indication can be managed making having a diagnosis worthwhile.”

ASD awareness is growing and stigma reducing

Recent evidence suggests that both parents and physicians have become more aware of ASD than they were previously, which has both decreased the stigma around the disease—encouraging parents to seek diagnosis earlier—and increased research efforts. According to GlobalData’s epidemiological study, the diagnosed prevalence of ASD was highest in children aged 5–9 years in the 7MM*.

Moody continues: “Greater awareness of ASD will significantly improve the lives of individuals with ASD and their families by reducing stigma and improving access to essential services. There has been increased education around developmental disabilities (especially within the UK and US). However, some markets, like France, still suffer with stigma surrounding ASD.”

Salter continues: “Early treatment of ASD helps with the development of communication, social, and learning abilities—and even with motor skills—vastly improving patients’ long-term outcomes and quality of life. Key opinion leaders interviewed by GlobalData agreed that improved early diagnosis is important, noting that the average age of diagnosis is too high, given the benefits of early intervention. Research suggests on average, there is a three-year delay between initial parental concern and an actual diagnosis of ASD, and delays in diagnosis have been exacerbated by the COVID-19 pandemic.”

*7MM: The US, France, Germany, Italy, Spain, the UK, and Japan

**5EU: France, Germany, Italy, Spain, and the UK

*** GlobalData’s 2022 June autism spectrum disorder survey, sample size of 117 high-prescribing psychiatrists, pediatricians, and primary care physicians, who represented the 7MM. In the survey, physicians ranked various unmet needs from one to nine, where ‘one’ indicated the most significant need and ‘9’ the least significant).