Systematic Review on Prevalence for Autism Spectrum Disorder with Respect to Gender and Socio-Economic Status

Abstract

The prevalence of Autism Spectrum disorder has been increased rapidly worldwide in last few years. However most of the estimation comes from developed regions of western countries. There are no reliable and consistent data from non-western or non-affluent countries. Aim: The primary aim of this systematic review was to synthesise the results of wide range of epidemiological studies to estimate prevalence of ASD with respect to gender and socioeconomic status (SES). Secondarily, available studies were analyzed with identified themes for assessing the trend of these studies. Methods: Based on pre-defined inclusion and exclusion criteria epidemiological reports were identified by internet search and recent relevant papers were included (2005-2015). Results: 27 eligible studies were identified for review of which 22 estimated Autism spectrum Disorder (ASD) or Pervasive developmental disorder (PDD) and 4 concentrated on typical Autism. Most of the studies used special educational and mainstream school records (N=11) for data extraction. Overall mean age of study samples ranged between ages 2-17 years. International classification of disabilities (ICD)-9 and 10 criteria as well as Diagnostic Statistical Manual (DSM)-III and IV criteria were retained for diagnostic assessment. The average prevalence of these twenty seven studies was 91.92 per 10,000 populations. The reported prevalence of ASD varied substantially by country and continent, use of methodology, assessment tools, gender, geographic region and Socioeconomic status (SES). Conclusion: Recent studies provided higher estimation and prevalence rate in developed or much affluent countries as well as urban areas. Also Parental high SES was found positively associated with prevalence of ASD. Analyses suggest more strong instruments and awareness is needed. Also more population based investigations is needed in rural as well as developing countries for revealing clear picture of this disability. countries. Therefore low or middle income regions of developed countries have not identified so much increase of ASD rate than high resource community and countries. According to a recent estimation epidemiological studies identified around 87% of the ASD cases in Europe, Japan and North America, while only 10% of the worlds children's lives in these countries [9]. Due to lack of knowledge, awareness and socioeconomic disparities majority of individuals with ASD living in low and middle income countries and were not identified properly. Therefore these unidentified peoples were not represented in world prevalence studies. Because of this inconsistent estimation recently researchers descended on debate over whether this is real increase or not. Several explanation have been proposed by the researchers for this high estimation including modified diagnostic criteria, improved diagnostic instruments, the broader definition of ASD, uses of different research