Age at ASD Diagnosis and Influential Factors: A Meta-Analysis and Systematic Review for 2012-2018
Objectives: To conducted a meta-analysis regarding the global average age at ASD diagnosis and a systematic literature review regarding influential factors on the age at ASD diagnosis between 2012 till 2018.
Methods: We performed a PubMed literature search with ‘age’ AND ‘diagnosis’ AND ‘ASD’ in title or abstract. We limited the search to studies published in English from January 2012 through February 2018 reporting the average age at ASD diagnosis of any ASD. Influential factors on the age of diagnosis were assessed from these identified studies. We conducted random-effects meta-analysis to assess the global mean age at ASD diagnosis. Also, we specified the mean age at diagnosis for study samples < 10 years of age so results can be interpreted within the scope of early detection.
Results: We found 40 studies reporting the average age at ASD diagnosis in 36 countries (n = 2141 215 individuals). Results show that the mean age at diagnosis (n=28 033 individuals) ranged from 29 to 571 months and meta-analysis show that the overall mean (95%CI) age at diagnosis was 55.5 (44.8;66.2) months. When studies were selected comprising children only <10 years of age (n=17 760 individuals), the mean age at diagnosis ranged from 30.81 to 74.7 months and meta-analysis showed that the overall mean (95%CI) age at diagnosis was 43.5 (40.0;47.0) months. Type of ASD diagnosis, ASD severity, additional diagnosis and region are the most frequently reported factors affecting the age at diagnosis.
Conclusions: Our systematic literature review and meta-analysis between 2012-2018 showed that the overall mean age at ASD diagnosis is 55.5 months, compared to the range of 38 and 120 months based on a literature review between 1990 and 2012. Although comparability of these outcomes is complex due to study design factors, these results indicate that although a younger age of diagnosis seems to be obtained, improvement in early detection of ASD should have constant attention.