Autism Spectrum disorders (ASD) in South Asia: a systematic review

Autism spectrum disorders (ASD) are a group of neurodevelopmental conditions characterized by social and communication deficits, stereotyped interests and repetitive behaviors [1]. Approximately one in 68 children are identified with ASD according to estimates from Centers for Disease Control and Prevention (CDC)'s Autism and Developmental Disabilities Monitoring (ADDM) Network [2]. Systematic reviews around the world estimated different prevalence rates of ASD [3‐6]. Williams et al. [3] estimated global ASD prevalence of 20 per 10,000 with high degree of heterogeneity among studies. Elsabbagh et al. [5] reported a global median ASD prevalence of 62 cases per 10,000 population which translates to one child out of 160. Baxter et al. [4] estimated prevalence of 7.6 per 1000 or one in 132 persons worldwide. In Asia, Sun and Allison conducted a systematic review in six Asian countries that excluded South Asian countries revealed prevalence of ASD from 1980 to present was 14.8 per 10,000 [6].

In Asia, the South Asia region represents more than 20% of the world’s population, yet the prevalence of ASD in this part of the world is still largely unknown. The region represents eight countries including Bangladesh, India, Pakistan, Nepal, Sri Lanka, Bhutan, Maldives, and Afghanistan [7]. The present study systematically reviews the prevalence of ASD in South Asia and identifies gaps in our current knowledge. Lack of significant authorship and research output for low and middle income countries (LMICs) stunts the development of evidence-based health policies and practice in LMICs [8]. This review aims to provide information on the epidemiology of ASD which will assist health professionals and policy makers in prioritizing relevant research and services in South Asia.

This paper reports prevalence of ASDs for the first time in South Asia. Epidemiological research on the prevalence of ASD has been conducted by only three countries. The available studies reported prevalence of ASD in South Asia ranging from 0.09% in India to 1.07% in Sri Lanka. This data indicates up to one in 93 children have ASD in this region.

The prevalence of ASD ranged from 0.15–0.8% in Bangladesh. In Dhaka, the capital of Bangladesh, prevalence was much higher (3%) [18]. One explanation for this higher prevalence in urban area may be mental health services are concentrated around institutions and no service is available at the primary health care (PHC) level [21]. In the urban hospital, only 12 children were diagnosed with autism in the year 2001 with this number increasing to 105 children in 2009 [22]. Autism related reported cases are increasing due to increased rate of incidence, awareness amongst parents and capability to diagnose the problem [22]. Bangladesh is a lower middle income country with a three leveled health care delivery system [23]. The health system in Bangladesh is pluralistic [24] and a significant proportion of rural people have faith in traditional healers [25, 26]. These factors may act as barriers to proper management of mental disorders [21]. In addition, appropriate care is often missing both at district and sub-district health facilities due to lack of trained professionals [27]. Early detection and early intervention are key to reducing the burden associated with these disorders [18].

In India, prevalence of ASD was unknown until early 2015. ASD research in India is still limited to largely clinic-based case reports, case series, retrospective chart reviews, qualitative studies and treatment studies. These studies did not meet our inclusion criteria as they cannot be considered representative of the general population. Authors of a recent case series reported that autism is not uncommon in India [28, 29]. Its diagnosis is frequently missed as there is tremendous lack of awareness and knowledge about the disorder among health professionals [28, 30]. The first reported prevalence data from India represented preliminary findings, based on a mid-term report submitted to the funding agency [19]. The reported prevalence among their studied pediatric population (1–10 years of age) would be lower if they consider higher cut off score as the ISAA tool has suboptimal validity in 3–9-year-old children [31]. Recent reported prevalence data from the south Indian state of Kerala [14] was higher than previously reported study [19]. This increase though in slow pace indicate the alarming increase in the prevalence of ASD in India. One recent study evaluated the ISAA in relation to the Childhood Autism Rating Scale (CARS) and the Developmental Disability- Children Global Assessment Scale (DD-CGAS) [32]. Another prevalence study that was excluded from this review was limited to siblings of children with ASD and almost equal in male and female siblings [33]. Nationwide study of the prevalence of neurodevelopmental disorders in India has begun and is being carried out by members of the International Clinical Epidemiology Network (INCLEN) including 2–9 years aged children per cluster across five sites (rural, urban, hilly, coastal and tribal) [34] by expanding on the well-known “10 Questions” screen from Bangladesh [35]. It is estimated that there are approximately 1.7–2 million children with Autism Spectrum Disorders in India [36]. Case reports and qualitative studies in India have shown that most diagnosed cases belong to middle-class families. Upper class families do not frequent public health centers to treat autistic children, and families from low socioeconomic strata do not access such facilities unless the child is acutely ill [28, 37, 38].

Perera et al. from Sri Lanka reported the prevalence of 10.7 per 1000 (1.07% or one in 93) [20]. It is relatively higher than the rest of this region, however, consistent with the prevalence rates in the Western world. It is not possible to compare and comment on regional differences in the absence of other studies for comparison. This reported prevalence study was not representative of the whole island. Poor knowledge about autism and lack of collaboration is common. Sri Lanka does not have the necessary infrastructure or trainers to provide intervention for these children.

In Pakistan, prevalence of ASD was limited to either hospital based or had been done in children with autism in special schools, and therefore difficult to generalize the results to other settings [39‐44]. There is no reliable estimate of ASD in Nepal as there is lack of awareness amongst people and diagnosis process is poor [45]. Notably, the Government of Nepal has implemented the National Policy and Action plan for Disability-2006 and categorized including autism [46]. Since there is no community based ASD prevalence data in these countries, it is difficult to allocate adequate financial, infrastructural and human resources to address the issue.

The 67th World Health Assembly adopted a resolution that sets out a clear set of actions to facilitate comprehensive inter-sectoral response to the needs of persons with ASD and other developmental disorders in all high, middle and low income countries (Agenda item 13.4, WHA 67.8) [47]. The United Nations General Assembly unanimously declared 2 April as World Autism Awareness Day (A/RES/62/139) to highlight the need to help improve the quality of life of children and adults, who are affected by autism, so they can lead full and meaningful lives.

Our study aimed at systematically reviewing available prevalence surveys of ASD in South Asia. The review is a useful contribution in identifying evidence gap and has important implications for government and NGOs working in this sector. This review identified only a limited number of studies on ASD conducted in this part of the world that limit our conclusion despite the alarming increase in the prevalence of ASD in recent years. To know the extent of ASD as a public health problem, there is an urgent need for all countries of this region to conduct well-designed epidemiological research using uniform and appropriate tools. Knowing the prevalence could help choosing screening and diagnostic tools that are applicable, culturally acceptable, and cost-effective to identify individuals who can benefit the most from early diagnosis and intervention.