Amendments to study protocol
| ‘Opt-out’ study invitation amended to ‘opt in’ invitation | An ‘opt-out’ approach was initially used to recruit through paediatricians. Parents were sent a letter from the paediatrician advising them that the research team would call them to explain the study, confirm eligibility and invite them into the study. Parents were asked to contact the study team or their paediatrician if they did not wish to learn more about the study or be contacted by the research team. The paediatrician then provided the research team with the contact details of families if they did not opt out within the 2-week period specified in the letter. This recruitment method was amended to an ‘opt in’ study invitation letter from paediatricians. |
| Age range amended | Age range extended to include 13 year olds who attend primary school at the time of recruitment. |
| Social Communication Questionnaire Lifetime form cut-off adjusted | Clinical cut-off score lowered from ≥15 to ≥11. This measure is used to assess ASD symptomology. There is evidence in the literature to support a lower cut-off score to capture children with higher-functioning ASD and Asperger’s disorder who may be missed by the use of a more stringent cut-off score.67 |
| Vineland inclusion criteria removed | The Vineland Adaptive Behaviour Scales, Third Edition (Domain Interview Survey) was originally conducted with families over the phone as a screening tool for intellectual impairment. This was proving to be too cumbersome for families and a barrier to enrolment. It was therefore removed as a requirement for eligibility. |
| Comorbid medical conditions exclusion criteria amended | Exclusion criteria for comorbid conditions refined to medical conditions affecting sleep or associated with intellectual disability. Original criteria comorbid medical (eg, epilepsy), neuropsychiatric (eg, Tourette’s) or syndromic genetic (eg, Fragile X) conditions. |
ASD, autism spectrum disorder.