Time trends in autism diagnosis over 20 years: a UK population-based cohort study

Ginny Russell, Sal Stapley, Tamsin Newlove-Delgado, Andrew Salmon, Rhianna White, Fiona Warren, Anita Pearson, Tamsin Ford

Research output: Contribution to journalArticlepeer-review

60 Citations (SciVal)


Background: Autism spectrum disorder is a diagnosis that is increasingly applied; however, previous studies have conflicting findings whether rates of diagnosis rates continue to grow in the UK. This study tested whether the proportion of people receiving a new autism diagnosis has been increasing over a twenty-year period, both overall and by subgroups. Method: Population-based study utilizing the Clinical Practice Research Datalink (CPRD) primary care database, which contains patients registered with practices contributing data to the CPRD between 1998 and 2018 (N = 6,786,212 in 1998 to N = 9,594,598 in 2018). 65,665 patients had a diagnosis of autism recorded in 2018. Time trend of new (incident) cases of autism diagnosis was plotted for all, and stratified by gender, diagnostic subtypes, and developmental stage: infancy and preschool, 0–5 years old; childhood, 6–11 years old; adolescence, 12–19 years old; adults, over 19 years old. Results: There was a 787%, exponential increase in recorded incidence of autism diagnoses between 1998 and 2018; R 2 = 0.98, exponentiated coefficient = 1.07, 95% CI [1.06, 1.08], p <.001. The increase in diagnoses was greater for females than males (exponentiated interaction coefficient = 1.02, 95% CI [1.01, 1.03], p <.001) and moderated by age band, with the greatest rises in diagnostic incidence among adults (exponentiated interaction coefficient = 1.06, 95% CI [1.04, 1.07], p <.001). Conclusions: Increases could be due to growth in prevalence or, more likely, increased reporting and application of diagnosis. Rising diagnosis among adults, females and higher functioning individuals suggest augmented recognition underpins these changes.

Original languageEnglish
Pages (from-to)674-682
Number of pages9
JournalJournal of Child Psychology and Psychiatry
Issue number6
Early online date19 Aug 2021
Publication statusPublished - 30 Jun 2022


  • Autism
  • autism spectrum disorder
  • clinical practice research datalink
  • diagnosis
  • primary care
  • time trends

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Developmental and Educational Psychology
  • Psychiatry and Mental health


Dive into the research topics of 'Time trends in autism diagnosis over 20 years: a UK population-based cohort study'. Together they form a unique fingerprint.

Cite this