Revisiting the Prevalence of Autism Spectrum Disorder among Omani Children: A multicentre study

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

Parental Age and the Risk of Autism Spectrum Disorder in Oman: A case-control study

Objective: This study aimed at evaluating advanced parental age as a risk factor for Autism Spectrum Disorder (ASD) in an Omani cohort. Methods: Case-control study of 278 ASD cases compared with 722 sex-matched controls retrieved from the electronic records of the Developmental Paediatric Clinic, Sultan Qaboos University Hospital (SQUH) between January 2015 and June 2016. Results: ASD cases (76.6% male) were mostly diagnosed between 3-4 years of age, with more than 50% of them originating from Muscat and Batinah governorates. Compared to controls, mothers from the case group had significantly higher educational level (post-secondary education versus high school/no formal education (odds-ratio (OR)=1.62; 95% C.I. 1.20-2.19). In a multivariate logistic regression, the odds ratio of maternal age as a risk for ASD increased dramatically with advancing age category (using age<25 as a reference, OR was 3.39, 6.12, 7.86 and 13.13 for age categories 25-29, 30-34, 35-39, and ≥40 years, respectively). The ORs of advancing paternal age as a risk for ASD were also statistically significant (using age<30 as referent, OR was 2.20, 2.36, and 3.12 for age categories 30-34, 35-39 and 40-44 years); however, there was a drop in the effect with paternal age ≥ 45 years (OR=1.42; 95% C.I .64-3.15). Conclusion: Both maternal and paternal increased age were associated with a higher risk of ASD; however, the association was more pronounced and more consistent with advanced maternal age compared to paternal age. Keywords: Autism; parental age; case-control stud

Intellectual Profiles of Children with Autism Spectrum Disorder: Identification of verbal and nonverbal subscales predicting intellectual quotient

Objectives: This study aimed to explore the intelligence quotient (IQ) profile among children with autism spectrum disorder (ASD) and identify the most important subscales that predict the IQ. The analysis of an intellectual profile with age and gender differentials and the identification of a battery of subscales of intelligence are important for clinical management of ASD among children and for facilitating placement for remedial and educational services. Methods: Data were collected through an exploratory study of 100 children aged between three and 13 years, who were referred to the department of child health and development in Sultan Qaboos University Hospital, a tertiary hospital, in Oman between June 2016 and June 2019. Results: Among the 100 participants of this study, 79% were male, resulting in a male–female ratio of 4:1. The mean of full-scale IQ was found to be 68.6 } 18.1. Furthermore, the mean of nonverbal IQ (73.5 } 17.5) was significantly higher than that of verbal IQ (65.5 } 17.6). Finally, more than half (61%) of the children were observed to have had mild to moderate impairment in their IQ levels. Conclusions: Age and gender showed no significant association with IQ level. The regression analysis identified nonverbal fluid reasoning, nonverbal visual-spatial processing, nonverbal working memory and verbal knowledge as the significant predictors of total IQ. The crucial dimensions of verbal and nonverbal IQ identified in this study can be used to evaluate complicated cases. Keywords: Autism; Intelligence; Oman