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Prevalence and Age of Onset of Regression in Children with Autism Spectrum Disorder: A Systematic Review and Meta‐analytical Update

A systematic review published in 2013 reported 32% of children on the autism spectrum experience skill loss, known as autistic regression. However, the frequency varied depending on definition and measures used to capture skills. Retrospective parent report and prospective observation indicate loss of language and/or social skills, with motor skills typically unaffected. Our aim was to update the prevalence and age of onset of autistic regression through a meta‐analysis of the literature to understand if there have been changes to the reported onset and prevalence since 2010. A systematic literature search was conducted using Medline, Embase, PsycINFO, and the Cochrane Library databases and included studies published from 2010 onward. Risk of bias assessment was performed on included studies. A random effects model was used to calculate the pooled prevalence and age of onset of autistic regression. Ninety‐seven studies were included in the systematic review, of which 75 studies involving 33,014 participants had sufficient data for meta‐analytic syntheses. The pooled proportion of autistic regression was 30% (95% confidence interval [CI]: 27–32%) but heterogeneity was high (I2 = 96.91) and did not reduce with sensitivity or subgroup analyses based on study design or clinical differences, respectively. Prevalence varied according to risk of bias (low: 27%) and definition of regression (language: 20%, language/social: 40%, mixed: 30%, and unspecified: 27%). Weighted average age of onset was 19.8 months. Findings from this meta‐analysis highlight the importance of developing a standardized definition of autistic regression, and tools to measure this at multiple time points during early childhood development.