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Original article

Vol. 153 No. 12 (2023)

Age at initial diagnosis of autism spectrum disorders: a retrospective comparison of screening techniques between the southern and northwestern regions of Switzerland

  • Michael Sommer
  • Bronwyn Glaser
  • Emiliano Soldini
  • Peter Weber
  • Gian Paolo Ramelli
Cite this as:
Swiss Med Wkly. 2023;153:40131


AIMS: Early diagnosis of autism spectrum disorders (ASD) offers the possibility of early intervention and, in turn, gains in adaptive behaviour, language and cognition. The aim of the present study was to analyse whether age at diagnosis of autism spectrum disorders decreased in two regions of Switzerland from 2006 to 2016 following the implementation of different screening and referral techniques. In southern Switzerland, systematic paediatric screening using the Modified Checklist for Autism (M-CHAT) in toddlers was implemented in 2013, whereas in northwestern Switzerland, periodic trainings were used to increase paediatrician awareness of ASD. We investigated which method was associated with a younger average age at diagnosis.

METHODS: We conducted a retrospective, two-centre study searching clinical records of children and adolescents (aged 0–16 years) diagnosed with ASD in two neuropaediatric departments at Swiss hospitals between January 2006 and December 2016. All patients were diagnosed via a standardised evaluation based on two approved diagnostic tests: the Autism Diagnostic Observation Schedule–Second Edition (ADOS-2) and the Autism Diagnostic Interview–Revised (ADI-R).

RESULTS: In southern Switzerland, training and subsequent widespread use of the M-CHAT among paediatricians appeared to contribute to a significantly younger age at diagnosis. Age at diagnosis did not significantly decrease during the same period in northwestern Switzerland.

CONCLUSION: Our results point to the possibility of successfully reducing age at diagnosis in specific geographic areas through the implementation of screening questionnaires, such as the M-CHAT, at year 2 well-baby visits.


  1. Prevalence of Mental Disorders in Children (Boat TF, Wu JT, editors). Mental Disorders and Disabilities Among Low-Income Children. Washington (DC); 2015.
  2. Fernell E, Eriksson MA, Gillberg C. Early diagnosis of autism and impact on prognosis: a narrative review. Clin Epidemiol. 2013;5:33–43. 10.2147/CLEP.S41714 DOI:
  3. Studer N, Gundelfinger R, Schenker T, Steinhausen HC. Implementation of early intensive behavioural intervention for children with autism in Switzerland. BMC Psychiatry. 2017 Jan;17(1):34. 10.1186/s12888-017-1195-4 DOI:
  4. Shattuck PT, Durkin M, Maenner M, Newschaffer C, Mandell DS, Wiggins L, et al. Timing of identification among children with an autism spectrum disorder: findings from a population-based surveillance study. J Am Acad Child Adolesc Psychiatry. 2009 May;48(5):474–83. 10.1097/CHI.0b013e31819b3848 DOI:
  5. Zwaigenbaum L, Bauman ML, et al; Early Screening of Autism Spectrum Disorder: Recommendations for Practice and Research. Pediatrics. 2015; 136: Suppl. 1. DOI:
  6. Rogers SJ, Vismara LA. Evidence-based comprehensive treatments for early autism. J Clin Child Adolesc Psychol. 2008 Jan;37(1):8–38. 10.1080/15374410701817808 DOI:
  7. Robins D, Fein D, Barton M. Modified Checklist for Autism in Toddlers, Revised. Italian Translation: Salomone E. Cecil C & Muratori F; 2014. DOI:
  8. Kamio Y, Inada N, Koyama T, Inokuchi E, Tsuchiya K, Kuroda M. Effectiveness of using the Modified Checklist for Autism in Toddlers in two-stage screening of autism spectrum disorder at the 18-month health check-up in Japan. J Autism Dev Disord. 2014 Jan;44(1):194–203. 10.1007/s10803-013-1864-1 DOI:
  9. Sunita, Bilszta JL. Early identification of autism: a comparison of the Checklist for Autism in Toddlers and the Modified Checklist for Autism in Toddlers. J Paediatr Child Health. 2013 Jun;49(6):438–44. 10.1111/j.1440-1754.2012.02558.x DOI:
  10. Petrocchi S, Levante A, Lecciso F. Systematic Review of Level 1 and Level 2 Screening Tools for Autism Spectrum Disorders in Toddlers. Brain Sci. 2020 Mar;10(3):180. 10.3390/brainsci10030180 DOI:
  11. Le Couteur A, Lord C, Rutter ML. Autism Diagnostic Interview – Revised. Italian Translation: Faggioli R, Saccani M. Persico (AM): Tancredi R, Parrini B & Igliozzi R. Giuntipsy Italy; 2005.
  12. Lord C, Rutter ML, Dilavore PC, Risi S Luyster RJ, Gotham K, Bishop SL, Guthrie W; ADOS-2: Autism Diagnostic Observation Schedule-Second Version. Italian Translation: Colombi C, Tancredi R, Persico A & Faggioli R. Hogrefe Italy. 2013.
  13. No authors listed. Early intervention for children with autism. Paediatr Child Health. 2004 Apr;9(4):267–77. 10.1093/pch/9.4.267 DOI:
  14. Rotholz DA, Kinsman AM, Lacy KK, Charles J. Improving Early Identification and Intervention for Children at Risk for Autism Spectrum Disorder. Pediatrics. 2017 Feb;139(2):e20161061. 10.1542/peds.2016-1061 DOI:
  15. Volkmar FR. Editorial: the importance of early intervention. J Autism Dev Disord. 2014 Dec;44(12):2979–80. 10.1007/s10803-014-2265-9 DOI:
  16. Guthrie W, Wetherby AM, Woods J, Schatschneider C, Holland RD, Morgan L, et al. The earlier the better: an RCT of treatment timing effects for toddlers on the autism spectrum. Autism. 2023 Mar;27(8):13623613231159153. 10.1177/13623613231159153 DOI:
  17. Reichow B. Overview of meta-analyses on early intensive behavioral intervention for young children with autism spectrum disorders. J Autism Dev Disord. 2012 Apr;42(4):512–20. 10.1007/s10803-011-1218-9 DOI:
  18. Reichow B, Barton EE, Boyd BA, Hume K. Early intensive behavioral intervention (EIBI) for young children with autism spectrum disorders (ASD). Cochrane Database Syst Rev. 2012 Oct;10:CD009260. 10.1002/14651858.CD009260.pub2 DOI:
  19. Dawson G, Rogers S, Munson J, Smith M, Winter J, Greenson J, et al. Randomized, controlled trial of an intervention for toddlers with autism: the Early Start Denver Model. Pediatrics. 2010 Jan;125(1):e17–23. 10.1542/peds.2009-0958 DOI:
  20. Remington B, Hastings RP, Kovshoff H, degli Espinosa F, Jahr E, Brown T, et al. Early intensive behavioral intervention: outcomes for children with autism and their parents after two years. Am J Ment Retard. 2007 Nov;112(6):418–38. 10.1352/0895-8017(2007)112[418:EIBIOF]2.0.CO;2 DOI:[418:EIBIOF]2.0.CO;2
  21. Fenske EC, Zalenski S, Krantz PJ, McClannahan LE. Age at intervention and treatment outcome for autistic children in a comprehensive intervention program. Anal Intervent Dev Disabil. 1985;5(1-2):49–58. 10.1016/S0270-4684(85)80005-7 DOI:
  22. Smith DP, Hayward DW, Gale CM, Eikeseth S, Klintwall L. Treatment Gains from Early and Intensive Behavioral Intervention (EIBI) are Maintained 10 Years Later. Behav Modif. 2021 Jul;45(4):581–601. 10.1177/0145445519882895 DOI:
  23. Elder JH, Kreider CM, Brasher SN, Ansell M. Clinical impact of early diagnosis of autism on the prognosis and parent-child relationships. Psychol Res Behav Manag. 2017 Aug;10:283–92. 10.2147/PRBM.S117499 DOI:
  24. Elder JH, Brasher S, Alexander B. Identifying the Barriers to Early Diagnosis and Treatment in Underserved Individuals with Autism Spectrum Disorders (ASD) and Their Families: A Qualitative Study. Issues Ment Health Nurs. 2016 Jun;37(6):412–20. 10.3109/01612840.2016.1153174 DOI:
  25. Ozonoff S, Heung K, Byrd R, Hansen R, Hertz-Picciotto I. The onset of autism: patterns of symptom emergence in the first years of life. Autism Res. 2008 Dec;1(6):320–8. 10.1002/aur.53 DOI:
  26. Vivanti G, Prior M, Williams K, Dissanayake C. Predictors of outcomes in autism early intervention: why don’t we know more? Front Pediatr. 2014 Jun;2:58. 10.3389/fped.2014.00058 DOI:
  27. Stahmer AC, Schreibman L, Cunningham AB. Toward a technology of treatment individualization for young children with autism spectrum disorders. Brain Res. 2011 Mar;1380:229–39. 10.1016/j.brainres.2010.09.043 DOI:
  28. Paynter J, Trembath D, Lane A. Differential outcome subgroups in children with autism spectrum disorder attending early intervention. J Intellect Disabil Res. 2018 Jul;62(7):650–9. 10.1111/jir.12504 DOI:
  29. Howlin P, Asgharian A. The diagnosis of autism and Asperger syndrome: findings from a survey of 770 families. Dev Med Child Neurol. 1999 Dec;41(12):834–9. 10.1111/j.1469-8749.1999.tb00550.x DOI:
  30. Ramelli V, Perlini R, Zanda N, Mascetti G, Rizzi E, Ramelli GP. Early identification of autism spectrum disorders using the two-step Modified Checklist for Autism: experience in Southern Switzerland. Eur J Pediatr. 2018 Apr;177(4):477–8. 10.1007/s00431-018-3097-y DOI:
  31. Myers SM, Johnson CP; American Academy of Pediatrics Council on Children With Disabilities. Management of children with autism spectrum disorders. Pediatrics. 2007 Nov;120(5):1162–82. 10.1542/peds.2007-2362 DOI:
  32. Sánchez-García AB, Galindo-Villardón P, Nieto-Librero AB, Martín-Rodero H, Robins DL. Toddler Screening for Autism Spectrum Disorder: A Meta-Analysis of Diagnostic Accuracy. J Autism Dev Disord. 2019 May;49(5):1837–52. 10.1007/s10803-018-03865-2 DOI:

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