1Department of Child Health, Sultan Qaboos University Hospital, Muscat, Oman; 2Department of Child and Adolescent Psychiatry, Al-Massarah Hospital, Muscat, Oman; 3Pediatric Department, Royal Hospital, Muscat, Oman; 4Department of Woman and Child Health, 5Directorate General of Primary Health Care, Ministry of Health, Muscat, Oman; 6Department of Statistics, College of Science, Sultan Qaboos University, Muscat, Oman *Corresponding Author’s e-mail: ahmed30411@gmail.com إعادة النظر يف معدل إنتشار إضطراب طيف التوحد بني األطفال العمانيني دراسة متعددة املراكز وطفة املعمرية، اأحمد بابكر اإدري�ض، �صمر دقاق، منى ال�صكيلي، زوينة احلارثية، اأ�صيه النعمانية، فاطمة الهنائية، ثاقب جلي�ض، موزة احلامتية، حممد النجاري، م.مظهر الإ�صالم abstract: Objectives: This study aimed to provide an updated estimate of the prevalence of autism spectrum disorder (ASD) among Omani children. Methods: This retrospective descriptive study was conducted from December 2011 to December 2018. Data were retrieved from the three main autism diagnostic centres in Oman: Sultan Qaboos University Hospital, Royal Hospital and Al-Massarah Hospital. The ASD diagnosis was made by experienced clinicians based on the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The overall population prevalence estimates per 10,000 children aged 0–14 years old in Oman were calculated using the denominator of the mid-period population data. Results: A total of 1,705 ASD cases were identified with the majority of cases being male (78.1%). The overall prevalence rate of ASD was estimated at 20.35 per 10,000 children (95% confidence interval: 19.39–21.32) between 2012–2018. Boys were found to have a 3.4-fold higher prevalence of ASD than girls (31.23/10,000 versus 9.07/10,000). Regionally, the majority of cases were found in the capital, Muscat, where the highest prevalence was 36.51 cases per 10,000 children. Conclusion: The prevalence of ASD among Omani children is 15-fold higher than estimates from 2011. This increase can be attributed to improvements in diagnostic services, increased awareness of ASD, better screening programmes and changes in diagnostic criteria. In addition, this increase in prevalence suggests a need for a registry of developmental disabilities and more extensive diagnostic and rehabilitation services in Oman. Keywords: Autism Spectrum Disorder; Epidemiology; Prevalence; Oman. امللخ�ص: الهدف: هدفت هذه الدرا�صة اإىل اعادة تقدير ملعدل انت�صار اإ�صطراب طيف التوحد بني الأطفال العمانيني. الطريقة: اأجريت درا�صة و�صفية اإ�صرتجاعية يف الفرتة ما بني دي�صمرب 2011 حتي دي�صمرب 2018. مت جمعا لبيانات من ثالثة مراكز رئي�صية لت�صخي�ض اإ�صطراب طيف التوحد يف عمان، و هم م�صت�صفى جامعة ال�صلطان قابو�ض، امل�صت�صفى ال�صلطاين و م�صت�صفى امل�رسة. مت ت�صخي�ض اإ�صطراب طيف التوحد بوا�صطة اأطباء ذوي خربة مرتكزين على الإ�صدار اخلام�ض من الدليل الت�صخي�صي والإح�صائي لال�صطرابات العقلية )DSM-5(. مت تقدير املعدل الإجمايل لإنت�صار ال�صكان لكل 10,000 طفل الذي ترتاوح اأعمارهم بني 14–0 عاًما با�صتخدام املقام يف بيانات منت�صف الفرتة لعدد �صكان ُعمان. النتائج: مت ت�صجيل 1,705 حالة اإ�صابة با�صطراب طيف التوحد الذي كان اأكرث �صيوعا بني الذكور )78.1(. يقدر معدل النت�صار الإجمايل لإ�صطراب طيف التوحد ب 20.35 لكل 10,000 طفل. )%95 جمال الثقة: 19.39-21.32( بني 2012-2018. كان معدل اإنت�صارطيف التوحد اأعلى بني الذكور ب 3.4 �صعف عن الإناث )31.23/10,000 مقابل 9.07/10,000(. كان اأعلى معدل انت�صار للحالت يف العا�صمة م�صقط و هو 36.51 حالة لكل 10,000 طفل. اخلال�صة: معدل اإنت�صار اإ�صطراب طيف التوحد بني الأطفال العمانيني اأعلى بخم�صة ع�رس �صعًفا من تقديرات عام 2011. ميكن اأن تعزى هذه الزيادة اإىل التح�صن يف اخلدمات الت�صخي�صة، وتغيري معايريالت�صخي�ض و برامج ك�صف مبكر اأف�صل. ت�صري الزيادة يف درجة الوعي و اأنت�صار اإ�صطراب طيف التوحد اإىل احلاجة اإىل وجود �صجل لالإعاقات النمائية وخدمات ت�صخي�ض وتاأهيل اأكرث �صموًل يف ُعمان. الكلمات املفتاحية: اإ�صطراب طيف التوحد؛ علم الأوبئة؛ معدل انت�صار؛ �صلطنة عمان. Revisiting the Prevalence of Autism Spectrum Disorder among Omani Children A multicentre study Watfa Al-Mamri,1 *Ahmed B. Idris,1 Samar Dakak,2 Muna Al-Shekaili,2 Zuwaina Al-Harthi,3 Asia M. Alnaamani,4 Fatma I. Alhinai,5 Saquib Jalees,1 Moza Al Hatmi,4 Mohamed A. El-Naggari,1 M. Mazharul Islam6 clinical & basic research Sultan Qaboos University Med J, November 2019, Vol. 19, Iss. 4, pp. e305–309, Epub. 22 Dec 19 Submitted 26 Feb 19 Revisions Req. 21 Mar & 7 May 19; Revisions Recd. 27 Mar & 13 May 19 Accepted 30 May 19 https://doi.org/10.18295/squmj.2019.19.04.005 Advances in Knowledge - The prevalence of autism spectrum disorder among Omani children aged 0–14 years increased almost 15-fold from 2011 estimates. Application to Patient Care - This study’s findings indicate that a registry of developmental disabilities is needed and that diagnostic and rehabilitation services in Oman should be expanded. Revisiting the Prevalence of Autism Spectrum Disorder among Omani Children A multicentre study e306 | SQU Medical Journal, November 2019, Volume 19, Issue 4 Autism spectrum disorder (asd) is a neurodevelopmental disorder that is charact- erised by deficits in social communication and interaction as well as restricted repetitive patterns of behaviour, interests and activities.1 Although ASD is usually diagnosed after the age of three years, parental concerns commonly appear between the first and second years of life. Subtle characteristics are thought to be present even in infancy and include decreased social responsiveness, lack of empathy, absence of gestures, decreased pretend play and lack of attention to others.2 The gold standard tools for ASD diagnosis are based on behavioural observations that require the input of a clinician who is experienced in the diagnosis and treatment of ASD.1 The diagnostic criteria for ASD have been revised periodically, reflecting advances in research, practice and knowledge in this growing field. The Diagnostic and Statistical Manual of Mental Disorders fifth edition’s (DSM-5) diagnostic criteria improve the specificity of the ASD diagnosis at the expense of sensitivity.3 In the past, ASD was thought to be a rare condition. Recently, the prevalence of ASD diagnoses have increased worldwide from approximately 0.0002–0.0006% of all individuals prior to the 1990s to current estimates of up to 2.6%.4–6 Globally, the median ASD prevalence is estimated to be 62 per 10,000.6 Some explanations for the increase in the observed prevalence of ASD include the development of better identification and screening methods, changes in diagnostic criteria, increased awareness among parents and clinicians, changes in the availability of services and in risk factors or aetiological causes.7,8 Based on available data, publications have reported that the prevalence of ASD ranges from 1.4 to 29 per 10,000 children among Arab Gulf countries.9,10 These prevalence estimates differ from the ASD prevalence rate estimated by the Centres for Disease Control and Prevention which reports that 1 in 59 children in the USA are affected.11 A South Korean study found a higher prevalence rate of ASD (about 1 in 38 children) than in Arab Gulf countries, which suggests that better screening methods may lead to substantially higher estimates of ASD’s global prevalence in the future.12 Broadening the DSM-5’s diagnostic criteria may play a role in differences in prevalence estimates as most publications from Arab Gulf countries are based on the DSM-4 criteria.13–15 However, the similar sociocultural factors and underdiagnosis of cases might be a comm- onality amongst Arab Gulf countries, including Oman. The prevalence of ASD in the Omani population was estimated to be 1.4 per 10,000 children in 2011, which could most likely be an underestimation of the actual number of ASD cases.13 Since the developmental paediatric services in Oman are still in their infancy, underdiagnosis and under-reporting still place major constraints on estimations of ASD’s true prevalence.13,16 Accurate prevalence estimates are essential for planning policy and service needs and identifying potential risk factors for ASD. The increase in ASD prevalence world- wide has raised concern among national governments and international agencies to take action in terms of advocacy and policy, research and service devel- opment.17,18 Therefore, this study aimed to examine the prevalence of ASD among Omani children in view of increasing awareness and developing better diagnostic services and broader diagnostic criteria. Methods This retrospective descriptive study was conducted between December 2011 and December 2018. Data were retrieved from the three main autism diagnostic centres in Oman: Sultan Qaboos University (SQU) Hospital, Royal Hospital and Al-Massarah Hospital. These three autism diagnostic centres are the only formal sources of diagnosing and recording ASD in Oman among the target population; thus, these three centres were likely to capture most of the diagnosed ASD cases in the country. Fulfilment of DSM-5 criteria formed the basis of the ASD diagnoses. The identified subjects were reviewed thoroughly to ensure the absence of repetition, since different hospitals in Oman do not share electronic records. The target population consisted of all children below 14 years old who had been referred to a main diagnostic centre and formally diagnosed with ASD. Demographic data included age, gender and region/governorate of residence. In addition, the age at diagnosis was also recorded. Clinical inform- ation was obtained from the medical records at each study site. As this study used retrospective data collected over seven years, period prevalence rates at national and subnational levels were used to reflect the proportion of patients with a particular disease or attribute at any time during the study’s timeframe. Period prevalence rates were calculated using a mid-period population aged 0–14 years as the denominator, which corresponds to the mid-year population of the year 2015 from a previously published report on Oman population stat- istics by the National Centre for Statistical Information.19 A Chi-square test was used to compare groups. A P value of less than 0.05 was considered statistically significant. Ethical approval was obtained from the Medical Research & Ethics Committee of the College of Medicine & Health Sciences, SQU and the Centre of Studies and Research, Research Committee, Ministry of Health, Oman in January 2017 (MREC #1726; Unique Identification Code #5820, respectively). Watfa Al-Mamri, Ahmed B. Idris, Samar Dakak, Muna Al-Shekaili, Zuwaina Al-Harthi, Asia M. Alnaamani, Fatma I. Alhinai, Saquib Jalees, Moza Al Hatmi, Mohamed A. El-Naggari and M. Mazharul Islam Clinical and Basic Research | e307 Results A total of 1,705 cases of ASD were identified during the study period out of a mid-interval population of 837,655 children aged 0–14 years old. Most patients were below five years old (62%) and predominantly male (78.1%; P <0.001). The mean age of children with ASD was 4.8 ± 2.4 years. More than one-third (37.3%) of the ASD cases were recorded in Muscat governorate, followed by Al-Batinah North governorate (15.7%). The fewest cases were recorded in the Musandam and Al-Wusta governorates (0.2% and 0.3%). This distribution of ASD cases is somewhat consistent with the distribution of the targeted population across Oman [Table 1]. The overall estimate of the prevalence of ASD in Oman was found to be 20.35 per 10,000 children (95% confidence interval [CI]: 19.39–21.32). Males had a significantly higher (3.6-fold higher) prevalence of ASD than females (31.23/10,000 versus 9.07/10,000; P <0.001) [Table 1]. This finding was true for all age groups [Figure 1]. The prevalence of diagnosed ASD cases showed an association with age. It was higher among children under five years old (30.34/10,000) compared to children aged 5–9 years old (20.2/10,000) and children aged 10–14 years old (4.52/10,000). The prevalence of ASD was found to vary significantly across Oman’s administrative regions, with the majority of cases found in the capital, Muscat, where the preval- ence was 36.51 cases per 10,000 children (95% CI: 33.68–39.34). The prevalence in Al-Batinah North, being the second more populous region, was sign- ificantly lower (16.14/10,000; 95% CI: 14.21–18.07). However, outside of Muscat, the prevalence was highest in Ash-Sharqiyah South (20.65/10,000; 95% CI: 17.22–24.08) and lowest in Musandam (4.27/10,000; 95% CI: 0.09–8.45) [Table 1]. Discussion The prevalence of ASD among Omani children increased almost 15-fold since 2011 estimates.13 This finding could be attributed to an increase in the autism detection rate among the Omani population rather than a real environmental increment. Another factor Table 1: Distribution of children aged 0–14 years with autism spec- trum disorder (ASD) and estimated prevalence of ASD in Oman (N = 1,705) Characteristic n (%) Mid-year population Estimated prevalence/ 10,000 children (95% CI) P value* Gender Male 1,332 (78.1) 426,450 31.23 (29.56–32.91) <0.001 Female 373 (21.9) 411,205 9.07 (8.15–9.99) Age in years 0–4 1,057 (62) 348,419 30.34 (28.51–32.16) <0.0015–9 550 (32.3) 272,309 20.2 (18.51–21.88) 10–14 98 (5.7) 216,927 4.52 (3.62–5.41) Mean age in years ± SD 4.8 ± 2.4 - - - Region/governorate Muscat 636 (37.3) 174,198 36.51 (33.68–39.34) <0.001 Dofar 64 (3.8) 70,222 9.11 (6.88–11.35) Musandam 4 (0.2) 9,373 4.27 (0.09–8.45) Al-Buraymi 12 (0.7) 18,416 6.52 (2.83–10.2) Ad-Dakhliyah 231 (13.5) 115,140 20.06 (17.48–22.65) Al-Batinah North 267 (15.7) 165,423 16.14 (14.21–18.07) Al-Batinah South 182 (10.7) 100,311 18.14 (15.51–20.78) Ash-Sharqiyah North 119 (7) 58,244 20.43 (16.76–24.1) Ash-Sharqiyah South 139 (8.2) 67,307 20.65 (17.22–24.08) Adh-Dhahirah 46 (2.7) 50,873 9.04 (6.43–11.65) Al-Wusta 5 (0.3) 8,148 6.14 (0.76–11.51) Total 1,705 (100) 837,655 20.35 (19.39–21.32) CI = confidence interval; SD = standard deviation. *Using Chi-square test. Figure 1: Estimated prevalence of autism spectrum disorder among the current study cohort classified by age and gender (N = 1,705). Revisiting the Prevalence of Autism Spectrum Disorder among Omani Children A multicentre study e308 | SQU Medical Journal, November 2019, Volume 19, Issue 4 that could contribute to this increase is the launch of the National Screening Programme for Autism and Other Developmental Disorders in early 2017. Although the programme has not reached its full potential yet, the collateral outcomes of awareness and media interest could have played a role. Although no published data are available for comparison, unpublished data from SQU estimated the prevalence by the end of 2015 to reach 8.5 cases per 10,000 children.20 Increasing comm- unity awareness plays a major role in detecting ASD within the general population. It has been reported that family members are the first to notice and report children’s milestones.21 Although knowledge about autism in Omani school-teachers in mainstream schools has been described as low, it can be assumed that their awareness of ASD, like awareness in the general population, has improved in the last decade mostly due to media and increasing diagnostic facilities and governmental interests.22 Moreover, the increasing prevalence of ASD has been attributed to diagnostic substitution as the increment in the autism diagnosis has been accompanied by a decrease in labelling intellectual disability.23 The gender distribution found in the current study is comparable with international autism data.6,11,12 The vast majority of patients had a presenting age below four years old, which is in agreement with published studies on autism.24–26 The paucity of cases diagnosed in the older age group may be affected by the degree of the severity of the cases that were detected and referred from peripheral facilities. Coo et al. attributed similar findings to the possibility that mild-to-moderate cases were mixed in mainstream schools and special needs classes and, in these settings, were misclassified as intellectually disabled or as having learning difficulties rather than ASD.23 ASD is not limited by geographical or political boundaries unless it is linked to hidden genetic or environmental factors; hence, the differences in the prevalence of ASD among governorates may be due to an inconsistency in referral policies and accessibility to services.27,28 The findings of a relatively higher prev- alence of ASD in Muscat and Ash-Sharqiyah regions highlight the importance of determining why these regions have a higher prevalence of ASD and develop region-specific approaches. The current study’s estimation of the prevalence was based on a hospital-based sample; thus, a major limitation may arise from the fact that many undiagn- osed cases were not included in this cohort, leading to an underestimation of the true prevalence. Conclusion The prevalence of ASD among Omani children is estimated to be 20.35 per 10,000 children. The prev- alence of ASD among Omani children is 15-fold greater than estimates from 2011. This rise can be attributed to improvements in the detection rate due to increasing awareness and screening programmes, better diagnostic services and changing diagnostic criteria. A registry of developmental disabilities should be established and diagnostic and rehabilitation services should be expanded. c o n f l i c t o f i n t e r e s t The authors declare no conflicts of interest. f u n d i n g No funding was received for this study. References: 1. American Psychiatric Association. Autism spectrum disorder. 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