Protocol for a longitudinal study investigating the role of anxiety on academic outcomes in children on the autism spectrum.

BACKGROUND: Children on the autism spectrum are consistently reported to underachieve compared to ability. In typically developing children, anxiety is a strong predictor of poor school performance. Despite the high prevalence of anxiety disorders among children on the spectrum, the impact of their anxiety on academic achievement is under-researched. The main aim of this project is to determine the moderating role anxiety may have in the development of academic learning behaviours (academic enablers) in children on the spectrum. This project addresses a gap in knowledge about the possible associations between anxiety and academic achievement in children on the spectrum. Understanding these associations opens up the possibility of new intervention pathways to enhance academic outcomes through anxiety reduction/prevention.
METHODS: This longitudinal study will aim to recruit 64 children on the spectrum aged 4-5 years and their parents. Information will be gathered from children, parents and teachers. Children will be randomly assigned to one of two conditions in order to experimentally manipulate anxiety levels in the sample: experimental (to receive an anxiety reduction/prevention program, N = 32) or control (no intervention/treatment as usual, N = 32). The primary outcome measures are child academic skills and enabling behaviours assessed using the Academic Competence Evaluation Scales and the WIAT-II. Anxiety will be assessed through parent and teacher report. Assessments will be conducted at baseline, post-experimental manipulation of anxiety, and within the first year of formal schooling. It is hypothesised that anxiety will moderate the relationship between autism characteristics and academic enablers. DISSEMINATION: Results will be disseminated through peer-reviewed manuscripts and conference presentations. Lay summaries will be provided to all participants and available on the research centre website.

Introduction

Children on the autism spectrum are consistently reported to underachieve academically compared to their ability [1-3]. These levels of underachievement remain present into adulthood [4], and are associated with reduced social and vocational outcomes [5]. Academic underachievement is understudied in autism, despite its high prevalence and potentially long-lasting impact. Consequently, little is known about associated factors [6]. In a review of 19 studies investigating academic achievement in autism, Keen et al. identified no consistent predictors [7]. Since this was published, there have been some studies linking previously unexplored factors, such as some elements of executive functioning, to academic attainment [8,9]. Notable from the work to date is the lack of research on academic enablers: attitudes and behaviours that facilitate students’ participation in and benefit from academic instruction in the classroom’ [10].

Academic success relies on a combination of academic skills and enablers that include engagement, motivation, study skills, and social skills [11]. Our pilot research has shown that these enablers are poorer in students on the spectrum compared to children without autism. Critically, in children on the spectrum, these academic enablers were stronger predictors of academic achievement than language skills, even in children as young as 5 years old [12]. It is not clear, however, why students on the spectrum have poorer scores on academic enablers, or whether it is possible to enhance these to improve academic outcomes. One plausible hypothesis is that anxiety (a common co-occurring experience in autism) is impacting on or possibly interacting with the child’s academic enablers and their ability to engage and participate in education, making it more difficult for students to benefit from academic instruction in the classroom and contributing to poorer academic achievement.

Anxiety disorders are the most common form of mental disorder in young people, affecting around 7% of Australian youth [13]. Anxiety disorders are even more common among children on the spectrum, affecting up to 40% [14] with an even larger number showing sub-clinical levels of elevated anxiety [15]. When researching anxiety in autism, it is important to consider both those who meet criteria for an anxiety disorder and those at the sub-clinical level where anxiety can still impact day-to-day functioning. Heightened levels of anxiety have been reported among children on the spectrum as young as 5–6 years of age [16]. These heightened anxiety levels have been identified as a significant predictor of educational quality of life using both parent and child self-report [17,18], and also rated by teachers and parents as one of the factors having the most impact on the educational support needs of students on the spectrum [19].

Among typically developing children, anxiety is a strong predictor of poor school engagement and performance [20]. Anxiety has been linked to below-grade-level academic achievement, school failure, and academic skill impairment [21]. Subsequently, reducing anxiety has led to improved school engagement and performance [20]. Based on these relations, the dramatic impact of autism on academic achievement may be at least partly a consequence of the high levels of associated anxiety.

Given that both academic outcomes and academic enablers are poorer in children on the spectrum, it is reasonable to hypothesise that the poor academic success noted within this population is likely a consequence of the impact of autism on the development and/or implementation of academic enablers. It is also highly likely that anxiety is impacting on these same enablers. For example, extensive evidence with older, typically developing children has demonstrated the impact of anxiety on social performance and interactions [22]. Similarly, perfectionism and worry, which are key components of anxiety, can have a negative impact on study skills and motivation [23]. At a broader level, enablers of good academic functioning often reflect the ability to focus attention and think flexibly. A core mechanism of anxiety, threat expectancy, interferes with a range of cognitive processes, including attentional focus [24]. In addition to heightened threat expectancy, an additional key mechanism in the maintenance of anxiety is a reduced ability to tolerate uncertainty (intolerance of uncertainty [IU]) [25]. High levels of IU are likely to be especially pertinent to children on the spectrum. Many of the core symptoms of autism reflect a need for consistency and predictability, suggesting that threats to consistency and predictability are likely to be highly distressing to these children. Several studies have shown high levels of IU among children, adolescents, and adults on the spectrum [26,27]. Additionally, IU has been found to mediate the relation between autism and anxiety [28], where higher levels of IU are associated with higher levels of anxious symptomatology in these individuals. IU has also been shown to predict parent and family responses to anxiety management [29,30] as well as levels of school functioning using parent and child reports, including those specific to quality of life in children on the spectrum [17,18,31,32].

In summary, it is likely that heightened anxiety, at least partially, interacts with academic enablers to contribute to the poor academic performance consistently reported for children on the spectrum. However, to date, this hypothesis has not been tested. The primary aim of this study is therefore to evaluate the role of anxiety on academic outcomes (academic skills, academic enablers) in children on the autism spectrum. The most valid way to determine causal status (i.e. that anxiety impacts upon academic outcomes) is through experimental manipulation. Therefore, this study will experimentally manipulate anxiety (through an intervention) to determine whether this manipulation impacts academic enablers and outcomes. The case for needing to experimentally manipulate anxiety is strengthend by the findings that that 70–80% of children on the autism spectrum experience elevated anxiety levels and40% of children on the spectrum have a clinical diagnosis of an anxiety disorder [14]. Therefore, experimental manipulation which aims to prevent or reduce anxiety increases the opportunity for a broader range of anxiety scores within the sample. An extensive body of literature has demonstrated the efficacy of skills-based intervention programs to reduce heightened anxiety among typically developing children as young as 3 years of age [33]. One such program is Cool Little Kids (CLK), a six-session, parent-led program that has demonstrated excellent outcomes in the reduction of anxiety among preschool-aged children. The core treatment strategy in this program is in vivo exposure, which primarily works via extinction to shift expectations of threat [34]. In a recent analysis, Bischof et al showed that CLK also led to reductions in anxiety among a group of preschool-aged children with co-occurring autism, with feedback from parents suggesting that future offerings of the intervention could use examples and information that was more autism focused [35].

Although CLK has shown promise in reducing anxiety among young children on the spectrum, its processes focus primarily on one mechanism of anxiety, threat expectancy. Given the elevated levels of both IU and anxiety noted in children, adolescents and adults on the spectrum [36,37], more complete reduction in anxiety might be achieved by also reducing IU. Rodgers et al [38,39] recently developed a parent-mediated intervention especially for children (aged 8–15 years) on the spectrum (Coping with Uncertainty in Everyday Situations; CUES) that has shown promising efficacy [38]. Therefore, combining the processes of CLK and CUES (hereafter termed CLK-CUES) should allow greater reduction in anxiety among children on the spectrum, leading to a stronger experimental manipulation of the critical variable.

Aim and hypotheses

The aim of this project is to determine the role that anxiety may have in the development of academic learning behaviours (academic enablers) in children on the spectrum. Experimental manipulations are the only way to determine causal status. Therefore, we will experimentally manipulate anxiety (through the CLK-CUES intervention) to determine if this manipulation affects academic outcomes at follow-up. This methodology will allow for the following research questions to be posed:

Is there evidence that anxiety is associated with academic enablers in children on the autism spectrum?

Does anxiety moderate the relationship between autism characteristics and academic enablers in these children?

The answers to these questions will inform a model for intervention aimed at children on the spectrum entering their first year of formal schooling. It is hypothesised that anxiety will moderate the relationship between autism characteristics and academic enablers and skills. Additional measures of factors associated with anxiety and/or academic achievement, such as sensory profiles and repetitive behaviours, are included so they can be accounted for in secondary analyses if required.

Methods and analyses

Overview of method

This project uses a longitudinal design with participants participating in three data collection points over 2 years: baseline (Time 1; T1); post-completion of the CLK-CUES program or the equivalent number of weeks after baseline for the control group (Time 2; T2, to check the efficacy of the experimental manipulation of anxiety); and during the first year of formal schooling (Time 3; T3).

Parents, and their children on the spectrum (4- to 5-year-olds), will be recruited the year prior to their child entering formal schooling. As shown in Fig 1, half of the parents will be randomised to receive the CLK-CUES program while the remaining half will form the control group. Randomisation of participants into these two groups ensures the randomisation of potentially confounding factors across the levels of anxiety. Groups will be run during school-terms to reduce any barriers relating to childcare. In order to minimise the risk of participant drop out between randomisation and commencement of the intervention, recruitment advertising will be timed to enable recruitment, initial assessment and randomisation occurs as close to the onset of the groups as possible whilst also allowing parents sufficient notice of group onset. Final assessments will be conducted within 6 months of children transitioning to formal schooling. Parents and children will complete measures at all time points (T1-T3), with additional data collected from the child’s schoolteacher at T3.

Fig 1

Flow diagram for study.

Trial registration

The primary aim of the study is to explore the role of anxiety on academic outcomes for young children on the autism spectrum. To determine causal status, an experimental manipulation of anxiety is requiresd. Therefore, some parents will receive a modified version of an intervention shown to have efficacy in reducing anxiety in neurotypical children and those on the autism spectrum [33] and others will not. Allocation into the intervention or control group will be randomised. The primary aim of the study is to explore the impact of anxiety on academic outcomes, but as assumption behind the experimental manipulation (that the intervention reduces anxiety) will require a comparison of the two groups on anxiety levels at Time 2 and 3, the study will be able to test the efficacy of this intervention to prevent or reduce anxiety. Therefore the study is registered with Australian New Zealand Clinical Trials Registry (ANZCTR) number ACTRN12620001322921. To ensure clear reporting of this protocol, the SPIRIT checklist has been used.

Recruitment and participants

As there has been no previous research exploring the effect of anxiety on academic outcomes for children on the autism spectrum, the target sample size was informed by a power analysis (using Gpower [40]) and determined through analysis of previous research on anxiety and academic outcomes in neurotypical students. In a large study of 715 elementary school students, Xu, Huebner and Tian (2021) report an effect size of anxiety on academic outcomes (when comparing high and low anxiety groups) of d = 0.68. Using this effect size in Gpower, the sample size required to conduct the linear regression with four predictor variables (autism severity, ability, anxiety and the interaction of autism and anxiety) on academic outcomes with a significant level of 5% and 80% power to reject the null hypothesis of no difference is 42.

A second power analysis was undertaken to ensure that there is a significant power to test for the effectiveness of the experimental manipulation. The effect size from Bischof et al [35] who piloted the original CLK program with children on the spectrum by evaluating outcomes within a larger population trial of 13 parents of children on the spectrum in the intervention group and 13 in the control group, was used. Bischof et al. reported an effect size of Cohen’s d = .91 on the anxiety measure (Preschool Anxiety Scale-Revised; PAS-R) [41] at 2-year follow up. Conservatively assuming a more modest effect (Cohen’s d = .75) and applying a retention rate of 90% [35] and a significance level of 5%, it is estimated that 64 participants (32 in each group) will be needed to obtain a statistical power of 80% to reject the null hypothesis of no difference. This calculation is based on the t statistic.

Based on these two power analyses and their assumptions, in order to ensure an accurate test of the experimental manipulation (i.e. a sufficient sample size to evaluate if the intervention resulted in a significant difference between the two groups on level of anxiety) and ensure a sufficient power in the linear regression to answer the reseach questions, 64 participants will be enrolled. The 64 parents will be recruited through social media and AEIOU autism early learning centres. If there is a shortfall of participants, other early intervention service providers in Queensland will be approached. Inclusion criteria state that parents will be eligible to participate if their child is aged 4–5 years, has a score indicating autism spectrum on the Autism Diagnostic Observation Schedule-2 (ADOS-2) [42], and has not yet commenced their first year of formal schooling and are able to attend the parent group sessions. There are no set exclusion criteria.

Recruitment will occur in waves to assist in meeting recruitment targets and to ensure sufficient available resources to implement the intervention with 32 parents. Each recruitment wave will comprise of 12–20 families. For each wave, the project manager will use a random number generator, to randomly allocate half of the families to the experimental condition (CLK-CUES anxiety prevention program) and half to the control condition (no intervention/ treatment as usual). Treatment as usual was selected as the comparator so as to allow for a broad range of anxiety levels across the two groups, and to indicate what would have been the common outcome had the intervention not been implemented. The project manager will notify parents of their group status via letter/email and will be asked to select the workshop location and time most appropriate for them. This project manager will also maintain a record of participants allocated to the conditions. The research team members responsible for collecting the direct pre- and post-intervention measures with the children will be blind to group allocation of participants and teachers will not be informed of which condition the child was in. It is not possible for parents or clinicians implementing the intervention to be blinded to group status, however, the clinicians are not involved in the data collection.

At T3, teachers of the participating children will be recruited to obtain their perspectives on the child’s school-related anxiety and academic competence. These teachers will be blind to the child’s group allocation. Given the longitudinal nature of this research, incentives (gift cards) will be offered to parents following data collection and free day of professional development on autism in schools offered to participating teachers following the end of data collection.

Intervention used to experimentally manipulate anxiety levels

The CLK-CUES intervention contains the standard information from the manualised CLK parenting program [43] with the addition of specific information from the CUES intervention as noted below. CLK is a parent-mediated, group-based intervention in which parents of children aged 3–6 attend six sessions (one per week) of 2 hours duration. In the current study, each group will consist of four to eight parents. If parents wish to discontinue the intervention, they are able to stop attending at any point.

As mentioned previously, CLK focuses on threat extinction and has been empirically validated for 3- to 6-year-olds at risk of developing anxiety [44]. To adapt this intervention for children on the spectrum, the research team have modified the clinician manual and parent workbook to include autism-specific content. This modified version contains all of the elements of the original CLK program but also draws upon the CUES intervention as well as broader knowledge related to anxiety in autism to incorporate autism relevant topics and strategies which address IU [38]. A pilot study (n = 3 parents) has provided positive feedback on the use of this modified program for young children on the spectrum. For more details on the intervention content, please contact the lead author.

The CLK-CUES program will be administered by a trained member of the research team and delivered in community settings across Queensland, Australia. Intervention fidelity will be assessed by the facilitator during session delivery using a purpose-designed content checklist. This same checklist will also be used by a second researcher to assess the fidelity of 20% of the sessions (using audio recordings of the sessions), this researcher will not know the identies of the group members, nor will they be involved in any of the direct assessments of the children or parents. Taken together, this will allow for inter-rater reliability to be established. Parent attendance and homework implementation will be recorded as measures of adherence.

Measures

In addition to collecting general demographic information and, at Time 2 and 3, information on any supports and services for anxiety that have been received since the last assessment, a range of child-directed, parent and teacher measures will be collected, these are presented in Tables 1–3, respectively. All parent/teacher questionnaires are administered via an online survey provider (REDCap). The order of the questionnaires will be set so that parents will be first asked to complete variables in the primary analyses before those required for secondary or exploratory analyses, to minimise the risk of any missing data on the trial outcomes. Child-directed assessments are administered in a 1:1 setting by a member of the research team. The two primary outcomes will related to academics; (1) academic enablers measured by the Academic Competence Evaluation Scales—Teacher Form (ACES-TF) [11] and, to minimise the impact of missing teacher data, (2) the Wechsler Individual Attainment Test (WIAT-III).

Table 1

Child assessments used in study.

Construct	Measure	Administration point	Reliability	Additional information
Autism characteristics	Autism Diagnostic Observation Schedule 2nd Edition (ADOS-2) [42]	T1, T2, T3	Test-retest reliability: rs = .83 - .87Inter-rater reliability: rs = .94 - .97 [43]	Although originally designed as a diagnostic assessment, the ADOS-2 is commonly used in research as a quantitative measurement of autism
Cognitive ability	Mullens Scale of Early Learning (MSEL) [45]	T1, T2, T3	Internal consistency: αs = .75 - .83 [45]	Well-standardised measure of ability for children aged 0–68 months. Provides a measure of child ability (visual reception, receptive language, expressive language, gross motor and fine motor) and a Developmental Quotient (DQ). Commonly used as a descriptive and outcome measure for children on the spectrum [46].
Academic performance	Wechsler Individual Achievement Test—Australian and New Zealand Standardised, 3rd Edition (WIAT-III) [47]	T3	Split-half reliability: rs = .69 - .98 [47]	Primary outcome measure 1Standardised measure of academic performance. For children aged 5 years, it provides assessments of alphabet writing, spelling, oral expression, listening comprehension, early reading skills, mathematics and numeracy
School connectedness	To be developed across duration of study	T3	n/a	This will need to be specifically developed as there are no measures of school connectedness for this age (see [48])

Note. T1 = Baseline; T2 = Post-intervention; T3 = 1-year follow-up.

Table 3

Teacher measures used in study.

Construct	Measure	Administration point	Reliability	Items (number and response procedure)
Child academic enablers	Academic Competence Evaluation Scales—Teacher Form (ACES-TF) [11]	T3	Internal consistency: α = .94 - .99Test-retest reliability: rs = .88 - .97 [11]	Primary outcome measure 273 items:33 on ability and importance of academic skills(1 = far below expectations; 5 = far above)(1 = not important; 3 = critical)40 on frequency and importance of academic enablers(1 = never; 5 = almost always)(1 = not important; 3 = critical)
Child school anxiety	School Anxiety Scale—Teacher Rating Scale (SAS-TR) [61]	T3	Internal consistency: α = .93Test-retest reliability:ICC = .70–92 [61]	Teachers will provide an indication of how often the child has demonstrated 16 school-related anxiety behaviours in the past 3 months (0 = never; 3 = always)

Age-appropriate subscales from a teacher-completed anxiety measure, the Preschool Anxiety Scale Revised (PAS-R) [39], and the parent-completed Anxiety Scale for Children—Autism Spectrum Disorder (ASC-ASD) will be collected so as to gain a quantifiable measure of anxiety [50]. As part of the intake process at AEIOU centres, the majority of children complete the ADOS-2 and Mullen Scales of Early Learning (MSEL) [45] assessments, and parents provide information on their child’s daily functioning (Vineland Adaptive Behavior Scales-3) [54]. To save repeating these assessments at T1, parents recruited via AEIOU centres will be asked to consent for these data to be shared with the research team. No restrictions are placed upon parents accessing any other interventions or services during their participation in the study, but they will be asked to note any services accessed since the previous assessment during their T2 and T3 questionnaire completion. Additional measures of variables which may impact outcomes (sensory profiles, impact of anxiety, restricted and repetitive behaviour) are included for secondary exploratory analyses, informed by the outcomes of the primary analysis.

Data analysis

Missing data that are deemed “missing at random” within a timepoint will be imputed as determined by the manual for each measure. Missing timepoints will be approached using intention to treat analysis. Scoring of all questionnaires completed on the online software is through syntax, minimising the risk of data entry errors, However, prior to any analysis, range checks and descriptive statistics will be undertaken to identify any data entry errors. Then, a manipulation check of anxiety levels at T2 and T3 will be undertaken to ensure the short and longer-term experimental manipulation of anxiety (through the parent intervention) was successful. Without this, causal status between anxiety and academic outcomes cannot be determined. This will be completed through a t-test with the independent variable of condition (received CLK-CUES intervention vs. control) and the dependent variable child anxiety levels.

To answer the first research question, and to determine whether anxiety is associated with academic outcomes in children on the spectrum, linear regression analyses will be conducted for each academic outcome. The primary variable of interest is the ACES academic enablers total score and subscales (Interpersonal skills, engagement and motivation), a teacher-completed questionnaire collected at T3. To reduce the risk of relying solely on teacher data, child assessments of academic competence will also be undertaken at T3. To investigate the variance in academic outcomes explained by anxiety when controlling for autism severity (ADOS score) and cognitive ability (DQ or adaptive behaviour), two linear regressions will be undertaken, one focussing upon teacher report and the other on parent report of anxiety. There will be four predictor variables in each linear regression; ADOS score, measures of ability, a measure of anxiety (teacher or parent) and the interaction of anxiety and ADOS score. One linear regression will have the outcome variable of the ACES score and one the WIAT score. The inclusion of the interaction between the anxiety and ADOS score will be used to answer the second research question and to determine whether anxiety moderates the relationship between autism and academic enablers or outcomes.

Methodological considerations

Bias in recruitment

This research project requires a significant time commitment from participants. All parents are asked to complete three online questionnaire batteries (1 hour each) and to accompany their child to three child-directed assessment sessions (2 hours each), totalling approximately 9 hours. A subsample of parents (i.e., intervention group) will participate in six intervention sessions (12 hours in total), with additional practice of the techniques required at home. This time commitment may influence which parents choose to participate, potentially resulting in a recruitment bias. Specifically, it may only be parents interested in the topic area who have access to the internet and/or sufficient time who are able to participate in the research.

To address these issues, we will ensure that each online survey is accessible by participants on multiple occasions over the course of 2 weeks. This will allow the questionnaires to be completed in smaller, more manageable sections. To minimize attrition, an email reminder will be sent to the parents once their questionnaires have been active for a week. A monetary incentive will also be provided at each timepoint for those who complete both the child-direct assessments and parent questionnaires. To further illuminate factors which contribute to attrition, we will compare the demographic information of parents who complete the study with those who leave.

No treatment control group

The control group in this research study do not receive any form of intervention. Although all parents are free to withdraw at any time, the control group may experience higher levels of withdrawal due to (a) parents being unaware of the importance of the control group, and instead feeling they are not contributing to the research; or (b) parents being specifically interested in participating in the CLK-CUES program. To address these possibilities, the information material will clearly state that the intervention sessions are not a clinical treatment program for anxiety as they are yet to be fully tested in parents of children on the spectrum. The material will also explain how both the intervention and control groups are equally important to the research, as comparisons between these groups can enhance understanding of the impact of anxiety in autism.

Although the use of a wait-list control or the provision of a secondary intervention was considered for parents in the control condition, these strategies were deemed inappropriate. By the end of T3 the children will exceed the target age-range for CLK, thus rendering the wait-list control unacceptable. Second, an alternative intervention could have an indirect effect on the children’s anxiety level, which may have implications for the critical experimental manipulation of anxiety. Given these limitations, it was decided that the control group would receive no treatment as this increases our ability to address the pertinent questions of whether anxiety is related to academic behaviours, and whether the CLK-CUES program is associated with a reduction (or prevention) of anxiety in children on the spectrum. It is important to note, however, that parents will be able to access outside services to assist with their child’s anxiety. This is true of parents in both the intervention and control groups. Data will be collected at each timepoint regarding any services accessed to assist with the management of anxiety.

Ethics and dissemination

Ethical clearance has been provided by Griffith University Human Research Ethics Committee (ref 2019/989) and has approval from the AEIOU Research and Innovation Committee board. Ethical approval will be sought from relevant educational departments once children transition. Any protocol modifications will be approved by these committees and then communicated to participants. All parents will provide informed consent for their child to participate. Parents will also consent to the teachers completing questionnaires about their child before the teacher is approached and asked to consent to participate in the research. We will also seek assent from the children prior to conducting any child-directed assessments.

Although there are no anticipated risks of participation in this research, some parents may become distressed when answering questions about their child’s autism or the associated difficulties. If this occurs, the research team can be contacted to discuss the questionnaire and, where necessary, can refer parents to specialised services. Additionally, as this is the first controlled implementation of the CLK-CUES intervention for children on the spectrum, its influence on the children’s behaviour is yet to be determined. If parents should become concerned about any changes in their child’s behaviour, they will be encouraged to speak with a member of the research team or a healthcare professional. Any adverse effects or unintended consequences will be immediately reported to the HREC ethics committee.

Data will be stored in line with the National Health Medical Research Council best practice [62] and will only be accessible to members of the research team. Data will be anonymised by allocating each participant a unique person identification code. The anonymised data will be saved on a password-protected secure computer drive or in a locked filing cabinet. Any personal identifiable information collected from participants (e.g., consent forms) will be stored securely in a separate location to the deidentified participant data. The dataset will remain with the PI at the host University and all co-investigators will have the opportunity to contribute to the results paper. Upon completion of the final publication from the project, the data will be stored in Griffith University’s Research Data Repository, which is accessible and searchable through a web interface.

The overall findings of this research will be communicated via published articles in peer-reviewed journals, conference presentations, and summary reports issued to participating parents and early intervention centres. To maintain anonymity, we will refer primarily to aggregated data rather than to individual responses. Parents will also receive a written summary of their child’s results at the end of each assessment stage (Time 1, 2, and 3). This summary can be shared by parents with healthcare professionals. If concerns are noted with regards to anxiety or behaviour scores, an additional statement will be added to the report to encourage parents to share the results with relevant professionals.

Significance and outlook

This study will make important contributions to the literature examining the role of anxiety in autism. In a methodological advance, anxiety will be experimentally manipulated using the CLK-CUES program. This will capture a range of anxiety levels, thus enhancing the scope and generalisability of the results. These findings will address whether anxiety moderates the relation between autism characteristics and academic learning behaviours, which can subsequently inform the development of interventions aimed at children on the spectrum entering their first school year.

Furthermore, as a secondary outcome, the check for experimental manipulation of anxiety will provide initial insight into the efficacy of the CLK-CUES program on the reduction (or prevention) of anxiety in autism. Until now, CLK has focused on threat expectancy, yet it is hypothesised that incorporating elements relating to the tolerance of uncertainty will provide a more robust intervention (although the current research design cannot test this hypothesis). By examining anxiety at two timepoints post-manipulation (i.e., T2 and T3) we are able to identify both the short-term and longer term impact of the CLK program. This also allows for the early developmental trajectory of anxiety (and its relation to academic behaviours) to be ascertained.

Study results will assist in informing clinicians, educators, children and their families about the influence of anxiety on academic skills. By being aware of the impact of anxiety on academic abilities, appropriate interventions can be selected to minimise/prevent anxiety and support the development of academic skills in young children on the spectrum. Moreover, should the experimental manipulation of anxiety via the CLK-CUES program be effective, this can be used as pilot data to provide the impetus for future large-scale clinical trials to better determine the efficacy of this program and its constituent components. Such larger trials could also then account for other co-occurring conditions with may impact upo academic outcomes and/or interact with anxiety in children on the autism spectrum.

Summary and conclusion

Anxiety disorders and sub-clinical levels of anxiety are prevalent within autism [13,14]. As anxiety is a key barrier to education in typically developing children [20], it is important to enhance our understanding of this relation for children on the spectrum. This study will collect data that examines the potential impact of anxiety on the academic enablers and academic achievement of young children on the spectrum (4- to 5-year-olds). The findings of this study will assist clinicians and educators in understanding how anxiety impacts academic performance, and will therefore inform the selection of strategies to reduce its impact.

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26 Apr 2021

PONE-D-20-28228

Protocol for a longitudinal study investigating the role of anxiety in the development of academic enablers in children on the autism spectrum

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does the manuscript provide a valid rationale for the proposed study, with clearly identified and justified research questions?

The research question outlined is expected to address a valid academic problem or topic and contribute to the base of knowledge in the field.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Partly

Reviewer #4: Yes

**********

2. Is the protocol technically sound and planned in a manner that will lead to a meaningful outcome and allow testing the stated hypotheses?

The manuscript should describe the methods in sufficient detail to prevent undisclosed flexibility in the experimental procedure or analysis pipeline, including sufficient outcome-neutral conditions (e.g. necessary controls, absence of floor or ceiling effects) to test the proposed hypotheses and a statistical power analysis where applicable. As there may be aspects of the methodology and analysis which can only be refined once the work is undertaken, authors should outline potential assumptions and explicitly describe what aspects of the proposed analyses, if any, are exploratory.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

Reviewer #4: Yes

**********

3. Is the methodology feasible and described in sufficient detail to allow the work to be replicable?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

Reviewer #4: Yes

**********

4. Have the authors described where all data underlying the findings will be made available when the study is complete?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception, at the time of publication. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above and, if applicable, provide comments about issues authors must address before this protocol can be accepted for publication. You may also include additional comments for the author, including concerns about research or publication ethics.

You may also provide optional suggestions and comments to authors that they might find helpful in planning their study.

(Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: I appreciate this opportunity to review this nicely planned research proposal. I would like to apologize for the late reply. I have some comments and suggestions before fully endorsing the publication of this proposal.

1) On Page 6, the authors directly stated “One plausible hypothesis is that anxiety….” I think the publication of this proposal is also of educational purpose, it thus is worth a short mentioning of other potential contributors, e.g. executive dysfunction and motivation problem, etc.

2) On Page 8, “In summary, it is likely that heightened anxiety…..” I appreciate the novel endeavor to link anxiety and academic enabler issues associated with children with ASD. However, there still are numerous other contributing factors to the problems in academic enablers, as mentioned in the last points. Therefore, I suggest that the summary sentences of Introduction should be toned down a bit to something like, “it is likely that heightened anxiety, at least partially, interacts with….”

3) On Page 9, Aim and hypotheses: I find that the modified CLK actually is based on the CLK and further integrates the element of CUES, as explained in the preceding paragraph. However, I don’t find the reason why only the CLK is highlighted in the description of the distinct intervention herein.

4) On Page 10, as the Preparatory Year should be a very Aussie-specific system, it is worth a concise introduction of this system to the non-Aussie readers.

5) Would the interindividual differences in early intervention impact the results? This element seems not to be taken into account in the data analysis part. Similarly, the interindividual differences in receiving services assisting with anxiety are not accounted for in the data analysis model.

6) It seems that this study does not exclude autistic children with co-occurring intellectual impairments. I think this practice is highly laudable. However, I wonder whether intellectual levels would impact the features of academic enablers, and the assigned school options, where the teachers might estimate the academic enablers differently, considering the different expectations for those with co-occurring intellectual disability.

7) On Page 13, the authors explicitly stated that this trial should not be considered a clinical trial. To me, this statement is inaccurate, as the secondary outcome actually involves the changes of anxiety after the CLK+CUES. This statement also contradicts with the discussion in the following paragraph, in which the potential significance in clinical improvement from the intervention is highlighted. Furthermore, as the authors highlighted, there has yet to be data on the CLK or CUES efficacy on anxiety in autism. The results of the current proposal certainly could generate the pilot data for the next-stage clinical trial.

Reviewer #2: Suggest a revision in order to simplify the protocol

As requested by PLoS, I have focussed my review on the more statistical aspects of this protocol. The protocol clearly describes an important research question, it is well written and seems to address all the key issues. However, my main concern, see also some specific points below, is the proposed complex and multi-faceted analysis described (Page 19). Further I suspect the sample size eventually achieved may not be sufficient to justify the analytical methods proposed. My general suggestion is therefore to simplify the protocol as much as possible and thereby reduce the amount of data collected so as to focus on key questions. Otherwise, I fear that there is a danger that the trial will fail for logistical reasons (too much missing data) and the key questions may not be answered. In brief, overloading the parents/children and the investigating team will diminish the chance of a successful completion of this randomised trial.

Specific points

1. As this is a ‘randomised trial’ I suggest this term replaces ‘study’ in the title.

2. Endpoints (Pages 9 and 10): The aims of the trial are not expressed as evaluating the effectiveness of the Anxiety Reduction/Prevention program (ARP) (a combination of CLK and CLUES) as compared to a non-intervention Control at 2-years post baseline (T3). Although this anticipated difference does form the basis of the sample size calculation (Page 11). Neither do they clearly state the aim in relation to the assessment at time T2.

3. Recruitment and Randomisation (Page 10): The protocol seems to suggest that there may be considerable delay between randomisation and the commencement of the intervention. In general terms, to avoid losses (parents/children changing their minds about participation) it is best to start the intervention (whether ARP or Control) as soon as possible after randomisation. Similarly baseline values should be recorded immediately prior to the randomisation. However, I am not sure of the logistical problems here.

4. Randomisation (Page 12): More detail of the randomisation process is required. This Includes: Who generates the list (with details of block size). Also, who holds the list (someone independent of the investigators) and how is the randomisation carried out (by phone to as statistical office?).

5. Sample size (Page 10): For the primary endpoint of the Academic Competence Evaluation Scales (ACES) at 2-years (Is this correct?) post-randomisation the standardised effect size, d = 0.75, then with test size 5%, power 80%, attrition rate (10%) I can confirm the sample size of N = 64 children. However, it would be useful if a direct (statistical) reference is given to the calculation method utilised.

6. Primary analysis: The anticipated attrition implies that only 58 children may be available for analysis. Although this is sufficient for the planned t-test (the phrase ‘and non-centrality parameter’ is not relevant here), I suggest that some of the further analyses, such as hierarchical multiple regression (page 11), will not be very sensible with such numbers. Neither does this method seem relevant to answering the main research question (see Point 2 above). This analysis requires the estimate of a difference between two means via the t-test, with the corresponding confidence interval. In addition, linear regression including intervention and the baseline assessment ACES may be useful.

6. Secondary analysis (page 19, last paragraph): Surely all that is needed here is a similar approach to Point 5 above. I don’t anticipate ANOVA would be required.

Reviewer #3: In this longitudinal experimental study protocol, authors aim to examine- a) the association between anxiety and academic learning behaviours, and b) whether anxiety moderates the association between the core behavioural characteristics of autism and academic learning behaviours in 64 children with autism aged 4-5 years. In this protocol, children will be randomized to receive either a modified Cool Little Kids (CLK) intervention (the combination of CLK and Coping with Uncertainty in Everyday Situations or CUES) (n=32) or no intervention/treatment as usual (n=32). Data collection will be completed at 3 different time points - at baseline (T1), at the end of a 6-month long intervention that parents will receive (T2) and at around 6 months of children transitioning to formal schooling (T3). Research team collecting data and teachers will remain blind. The primary outcome measure appears to be the ? teacher-administered Academic Competence Evaluation Scales assessing academic and enabling behaviours, and the secondary outcome measures are children academic attainment and parents and teacher-rated anxiety scales. This is not classified as a clinical trial since the primary outcome is not a health outcome. This study protocol has received appropriate IRB approval. One of the study authors declared a COI as the author (RMR) previously developed the CLK program.

Strengths:

This type of study examining the role of anxiety on the academic performance and learning in autistic children is much needed as they may pave the way to the successful development of school-based intervention that can improve outcomes in autistic children.

Use of parent- and teacher-rated measures, use of multiple measures including sensory, behaviour-related, cognitive and adaptive scales.

Carefully designed intervention, taking into consideration some common potential pitfalls.

Having an author from the population health sciences institute.

Limitations:

In my opinion, there are several limitations of this protocol:

I am not clear about the exact primary measure of this protocol. In the abstract and data analysis section Academic Competence Evaluation Scales - teacher rated form was mentioned as primary but in the table Wechsler individual achievement test was mentioned as the primary.

It would be easier to interpret if authors could add a figure to describe the study design.

Authors mentioned that there was no identified predictor of academic underperformance in autistic children. They reviewed literature to support their focus on anxiety in autistic children. However, this link appears non-specific as they also mentioned that anxiety is a strong predictor of academic underperformance in neurotypical children as well. Furthermore, given that clinically manifested anxiety is seen in 4 out of 10 autistic children, how would they justify the distribution of anxiety between the two groups? Would there be any value in having a neurotypical control group with anxiety? How about autistic children with and without significant anxiety to control for non-anxiety related autism factors contributing?

The authors included potential moderators (e.g. parental mental health, etc) in the analysis but they did not review information on these potential moderators related to autism in the introduction.

There are no exclusion criteria - what about unstable or uncontrolled medical conditions interfering with the academic ability, eg, epilepsy (common in autistic children), specific learning disability, intellectual disability, speech problem, genetic disorders that affect mobility and communication, presence of co-occuring mental health conditions such as attention-deficit hyperactivity disorder that affects academic performance. The design, if focused on anxiety as a mediator in the context of ‘autism’, should consider all these potential confounders.

Authors mentioned effect size calculation to justify the sample size but it is not clear if they referred to Cohen’s d and why did they use t-statistic when the proposed analysis plan includes multiple hierarchical regression, mixed ANOVAs.

The process of blinding is not also clear to me, for instance, authors mentioned that the research team members collecting data will be blind. However, the CLK intervention will be administered by a trained member of the research team and a second research team member will assess the validity. A separate team of analysts/researchers need to deliver the intervention. Also, will the data analysts be blind?

In the data analysis plan, authors need to include details regarding controlling for multiple comparisons. The sample size should reflect that as well but a sample size of 64 is not sufficiently justified.

The authors will collect information on sensory profiles, adaptive, etc but how they are going to handle all these additional measures in the analysis plan? It remains unclear.

I did not see any sex/gender consideration, which is a potentially powerful mediator in autism.

Reviewer #4: Thank you for the opportunity for reviewing this manuscript.

This is a research protocol investigating the relation between anxiety and academic achievement in children on the autism spectrum. This randomized longitudinal study aims to study the moderating effects of anxiety in development of academic enablers in children with autism spectrum disorder. Secondary outcome measures of the study are academic attainment and anxiety. The proposed study has a randomised, longitudinal design and a sample size of 64, based on appropriate sample size calculation. A battery of parent-reported measures and academic performance measures are proposed to test the hypothesis. The authors have used a robust methodology for this study and have addressed issues related to recruitment bias and waitlist control in the study. Use of SPIRIT checklist add rigour to the quality and transparency of the study protocol. This methodologically sound study can contribute to current understanding of the role of anxiety in autism and has the potential to inform development of interventions in children with autism in their early school years.

The authors of the study protocol clearly state the rationale for the study with clearly defined research questions. They also state that the hypothesis of heightened anxiety interacting with academic enablers to contribute to poor academic performance of children on the spectrum has not been tested to date. In this study, a modified anxiety reduction/prevention program comprising of Cool Kids program (CLK), a parent-led program for anxiety in pre-school children and Coping with Uncertainty in Everyday Situations (CUES), another parent mediated intervention, will be used as an intervention for anxiety. The authors have mentioned about a pilot study on the role of CLK in anxiety intervention. Please describe the modified program and cite additional supporting references, if any, about the role of CLK in moderating anxiety in autism.

CLK has been used for children in the age group 8-15 years and this study is designed for 4–5-year-old children on the spectrum. A pilot study of the modified version has been carried out but it is not clear if the participants were pre-school children. In addition, the validity of the modified anxiety reduction program as an intervention for the participants is not clear. Please address this issue in the research protocol.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Hsiang-Yuan Lin

Reviewer #2: Yes: David Machin

Reviewer #3: No

Reviewer #4: Yes: Anupam Thakur

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17 Jun 2021

We thank the editor and the reviewers for their feedback on the manuscript. We have attended to each reviewer’s comments in turn in the table uploaded with the manuscript.

Submitted filename: Response to reviewer 27.5.21.docx

Click here for additional data file.

27 Aug 2021

Protocol for a longitudinal study investigating the role of anxiety on academic outcomes in children on the autism spectrum

PONE-D-20-28228R1

Dear Dr. Adams,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

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Kind regards,

Tarek K Rajji

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does the manuscript provide a valid rationale for the proposed study, with clearly identified and justified research questions?

The research question outlined is expected to address a valid academic problem or topic and contribute to the base of knowledge in the field.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

2. Is the protocol technically sound and planned in a manner that will lead to a meaningful outcome and allow testing the stated hypotheses?

The manuscript should describe the methods in sufficient detail to prevent undisclosed flexibility in the experimental procedure or analysis pipeline, including sufficient outcome-neutral conditions (e.g. necessary controls, absence of floor or ceiling effects) to test the proposed hypotheses and a statistical power analysis where applicable. As there may be aspects of the methodology and analysis which can only be refined once the work is undertaken, authors should outline potential assumptions and explicitly describe what aspects of the proposed analyses, if any, are exploratory.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

3. Is the methodology feasible and described in sufficient detail to allow the work to be replicable?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

4. Have the authors described where all data underlying the findings will be made available when the study is complete?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception, at the time of publication. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above and, if applicable, provide comments about issues authors must address before this protocol can be accepted for publication. You may also include additional comments for the author, including concerns about research or publication ethics.

You may also provide optional suggestions and comments to authors that they might find helpful in planning their study.

(Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: I appreciate that the authors have addressed all my comments adequately. Now I am happy to endorse the publication of this protocol in the current form.

Reviewer #2: No comment as this is the second review but see my review.

Reviewer #4: Thank you for the opportunity to review the manuscript.

The authors have provided rationale for the proposed study as well as clearly identified and justified the research questions. It is a methodologically robust study with attention to detail.

Thank you for addressing the points mentioned in the reviewer's feedback.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Hsiang-Yuan Lin

Reviewer #2: Yes: David Machin

Reviewer #4: Yes: Anupam Thakur

6 Sep 2021

PONE-D-20-28228R1

Protocol for a longitudinal study investigating the role of anxiety on academic outcomes in children on the autism spectrum

Dear Dr. Adams:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Tarek K Rajji

Academic Editor

PLOS ONE

Table 2

Parent measures used in study.

Construct	Measure	Administration point	Reliability	Items (number and response procedure)	Additional information
Autism characteristics	Social Communication Questionnaire-Lifetime (SCQ) [49]	T1, T2, T3	Int consist: α = .84-.93	40 items (yes/no)	Assesses parent(s) perspective on their child’s autism characteristics Validated in children aged ≥4y [49]
Child anxiety	Preschool Anxiety Scale Revised (PAS-R) [41]	T1, T2, T3	Int consist: α = .72-.9212-month stability:rs = .60 - .75	34 items (0 = not true at all; 4 = very often true)	Secondary outcome measureMeasures generalised, social and separation anxiety, and specific fears in children < 6 years [41]
	Anxiety Scale for Children—Autism Spectrum Disorder (ASC-ASD) [50]	T1, T2, T3	Int consist: α = .94test-retest reliability: r = .84 [50]	24 items (1 = never; 4 = often)	Secondary outcome measureAutism-specific of anxiety in children ≥ 5y in descriptive and intervention studies [38]
Child intolerance of uncertainty	Responses to Uncertainty and Low Environmental Structure (RULES) [51]	T1, T2, T3	Int consist: α = .93	17 items(1 = not at all, 5 = very much)	Developed to measure need for rules and certainty for children aged 3–10 years [51]
	Intolerance of Uncertainty Scale–Parent (IUS-P) [28]	T1, T2, T3	Int consist: α = .90 (ASD) and .91 (TD)	12-items (1 = not at all; 5 = very much)	Assesses children’s emotional, cognitive and behavioural response to IU [28]
Impact of child anxiety	Child Anxiety Life Interference Scale Preschool (CALIS-P) [52]	T1, T2, T3	Int consist: ω = .88 [53]	18 items 5-point scale (“not at all” to “a great deal”)	Designed for children aged 3 to 5years to assess life interference attributed to fears and worries
Child adaptive behaviour	Vineland Adaptive Behavior Scales 3rd Edition (VABS-3) [54]	T1, T2, T3	Adaptive behavior composite Int consist: α = .97	99 items (communication) 109 items daily living99 items socialization76 items motor skills (0 = never; 2 = usually/)	Used extensively to measure adaptive behaviour of children on the spectrum.
Child repetitive behaviour	Repetitive Behaviour Scale—Early Childhood (RBS-EC) [55]	T1, T2, T3	Int consist: α = .70-.3Test-retest reliability: ICC = .87	34 items (0 = does not occur to 4 = occurs many times a day)	Developed for children from infancy through early school age [55]
Child sensory profile	Short Sensory Profile 2 (SSP-2) [56]	T1, T2, T3	Int consist: α = .57-.92Test-retest reliability: rs = .83 - .92 [56]	34 items 6-point scale (5 = almost always [>90% of time]; 0 = does not apply [have not observed the behaviour])	Measures behaviours associated with abnormal responses to sensory stimuli, and has been used successfully with children on the spectrum
Parental mental health	Depression Anxiety Stress Scales (DASS-21) [57]	T1, T2, T3	Int consist: α = .88 [58]	21-items (0 = did not apply to me at all; 3 = applied to me very much or most of the time)	Widely used in clinical and non-clinical samples, including parents of children on the spectrum [59]
School attendance	School Non-Attendance ChecKlist (SNACK) [60]	T3	n/a	Parents indicate which of 14 reasons best accounts for each school absence. If none is appropriate, they are asked to briefly describe the reason	Combines a vast literature on school attendance problems; screens for the four main categories of absenteeism (school withdrawal, school exclusion, truancy and school refusal) and non-problematic absenteeism [60]

Note. T1 = Baseline; T2 = Post-intervention; T3 = 1-year follow-up. Int. consist = Internal consistency.