Transparency and openness

This research meets Level 1 (Disclosure) for all eight aspects of research planning and reporting of the TOP Guidelines as well as Level 2 (Requirement) for data citation, design and analysis transparency, and study and analysis plan preregistration. We report how we determined our sample size, all data exclusions (if any), all manipulations, and all measures in the study, and we follow Journal Article Reporting Standards (JARS) [36]). All data, analysis code, and research materials are available upon request from the authors. Data were analyzed using IBM Statistics SPSS Version 25 [37]. The trial—which was begun in 2015—was listed with the Australian and New Zealand Clinical Trials Registry (ACTRN 210 12615001284550), and included a basic analysis plan.

Participants

Participant families were recruited through the media and local schools in metropolitan Brisbane between September 2015 and July 2017. Interestingly, 12 participant families came from suburbs designated as ‘rural and regional’ by the Australian Department of Home Affairs. To be included in the study, children were required to be 7–14 years of age and to meet diagnostic criteria for a primary diagnosis of a DSM-5 [38] anxiety disorder. The exclusion criteria were (a) parent is unable to understand and participate in the treatment; (b) child is concurrently receiving ongoing treatment for anxiety; and (c) child has a significant physical or intellectual impairment. Primary anxiety disorder diagnoses included separation anxiety disorder (n = 7, 9.6%), social anxiety disorder (n = 19, 26.0%), specific phobia (n = 20, 27.4%), and generalized anxiety disorder (n = 27, 37.0%); there were no statistical differences in the number of children with each primary anxiety disorder diagnosis across the two treatment conditions. Participants were not excluded from the study if the child met criteria for additional anxiety disorders or for a co-morbid non-anxiety diagnosis. In fact, 84% (n = 61) of children met criteria for one or more comorbid anxiety disorder diagnoses and about 43% (n = 31) of participants met criteria for a secondary, non-anxiety diagnosis (e.g., ADHD, major depressive disorder, oppositional defiant disorder). The final sample included 73 children and adolescents (Mean age = 8.40 years, 74% male sexFootnote 1) and their parents. Participant, parent, and family characteristics are presented in Table 1.

Table 1 Participant characteristics

Additionally, as noted below, parents also completed a measure of anxiety symptomology for the participating child’s closest-in-age sibling. Of the 73 participating children, 64 had one or more siblings. Siblings ranged in age from 2 to 26-years-old (M = 8.09, SD = 4.14); 52% were male sex. Of the siblings, 42 (66%) were younger than the target child, 21 (33%) were older, and 1 was a twin. Furthermore, 33 (52%) of the sibling pairs were the same sex and 31 (48%) were the opposite sex. Whether the target child had a sibling or not, the age and sex of the sibling closest in age, and whether the sibling was older or younger or of the same or different sex than the targeted child did not differ significantly between the group and workshop conditions.

Families were given a full description of the study before giving written informed assent/consent. A total of 77 families were tested for eligibility: three families did not meet the inclusion criteria and one family declined to participate. Thus, a total of 73 families were randomized to either the six-week group condition (n = 34) or the one-day workshop (n = 39). Participant flow through the study is summarized in Fig. 1.

Fig. 1

Participant flow. Received intervention: participant received the allocated treatment; withdrew: participant voluntarily withdrew from the study and had no further contact with the study; lost to contact: participant was unable to be contacted by the study; did not attend: participant failed to attend scheduled assessment. Remained in study and attended the next assessment point

Procedure

Ethical approval was obtained through the University of Queensland (#2014001727). Families attended an initial (pre) assessment interview at the university’s Psychology Clinic, where informed consent was obtained from all participants. Pre-treatment assessments were conducted by authors VC, IG, MJ and NRA (the first is an experienced clinical psychologist and researcher in the field of child anxiety; the other assessors were postgraduate clinical psychology trainees at the time). Assessments of child anxiety disorder and severity, children and siblings’ anxiety symptoms, parents’ own emotional symptoms, and family-level functioning were completed at four time-points: before treatment, 1-week post-treatment, and at 6- and 12-month follow-up. The assessment battery was completed by the target child’s mother in 79% of the families, by the father in 1% of the families, and by two parents (depending on timepoint) in 20% of the families. Families were compensated with a $20 gift card for each completed follow-up assessment.

Parents were randomly allocated to either the six-week group or one-day workshop condition via a computerized random generator with a 1:1 ratio. Post-treatment and follow-up interviews were completed either face to face or via telephone. Four additional postgraduate clinical psychology trainees served as independent evaluators (IEs) and conducted all follow-up assessments. All IEs were blind to participants’ condition and the design of the study. All interviewers had previous experience in administering the ADIS-IV-C/P, with training having involved a mix of videotaped and live diagnostic interviews. All interviewers met a reliability criterion of 85% in terms of the inter-rater reliability rating for both diagnoses and clinical severity ratings between the trainee and an expert diagnostician (the first author). All interviews were recorded and another trained IE (not involved in conducting any of the interviews) viewed a random twenty percent of interviews over the course of the study in order to ensure there was no interviewer drift. The inter-rater reliability was excellent for the primary diagnosis assigned (K = 0.98).

Of those randomized to treatment, retention of participants at the post-treatment, 6-month and 12-month time-points for the 6-week group was 85%, 82% and 71%. For those assigned to the one-day workshop, the rates were 77%, 72%, and 59%.

MeasuresClinician measuresStructured diagnostic interviews with parents

Caseness was determined based on outcomes of The Anxiety Disorders Interview Schedule for DSM-IV for Children—Parent Version [39]. The interview was modified to be consistent with the DSM-5 criteria [38]. Based on parent report, overall child anxiety diagnoses and clinical severity ratings (CSR) were assigned, where a CSR of the primary anxiety diagnosis of 4 or greater on a 9-point scale (moderate to severe) was considered to meet diagnostic criteria. Wherever possible, follow-up diagnostic interviews were conducted face to face at the Psychology Clinic, with a small proportion conducted over the telephone to accommodate parents. Research indicates that administration of the interview via telephone has good inter-rater reliability [40] and good comparability to the face-to face version of the interview [41].

Clinical global impressions: improvement scale (CGI-I)

The Clinical Global Impression—Improvement Scale (CGI-I), a seven-point scale ranging from 1 = very much improved to 7 = very much worse [42] was used to determine overall improvements in child anxiety. Scores of 1 and 2 indicate intervention success. Overall mean inter-rater reliability for the team of IEs was excellent (ICC = 0.917).

Questionnaire measuresChildren’s anxiety symptoms

Children completed the Spence Children Anxiety Scale (SCAS [43]); a 45-item self-report measure of anxiety symptomology. It consists of six anxiety subscales that comprise a total score which is reported in the current study. Cronbach’s alpha in this study for the total score was 0.923. Parents also completed the parent version of the Spence Children Anxiety Scale (SCAS-P; [43, 44]) for the child in question (Cronbach's alpha in this study was 0.885).

Family-level outcomes

Sibling anxiety, parent anxiety and stress symptoms, and overall family functioning were assessed as secondary outcomes using the SCAS-P, the Depression Anxiety and Stress Scale (DASS-21 [45]), and the Family Assessment Device—General Functioning Subscale (FAD-GF [46]) respectively. Parents were asked to complete the SCAS-P about the sibling closest in age to the ‘identified child’. They also completed the Depression Anxiety and Stress Scale, a 21-item self-report adult measure designed to measure the symptoms of depression, anxiety and stress; the anxiety and stress scores are reported in the current study (Cronbach's alpha in this study was 0.738 [DASS Anxiety], and 0.825 [DASS Stress]). The FAD-GF is a 12-item self-report measure that utilizes a four-point Likert scale (1 = strongly agree and 4 = strongly disagree) to indicate problematic functioning in the family. Lower scores indicate better functioning. Internal consistency in this study was good (α = 0.858).

Intervention

Triple P—Positive Parenting Program [47] is a public health approach designed to strengthen parenting and support families. It is a multilevel parenting intervention of varying intensities. The intervention is offered at five levels, ranging from a universal public communication campaign on positive parenting (Level 1) to intensive parenting interventions for severe and complex presentations within families (Level 5). Considerable evidence has been found for the efficacy of Triple P [48, 49].

Fear-Less Triple P (FLTP [31, 50]) is a Level 4, Triple P intervention for childhood anxiety. The parent-only CBT intervention consists of a suite of programs allowing for flexibility of delivery. This study investigated the outcomes of delivery modes of the six-weekly group sessions and the one-day workshop format. FLTP is designed to empower parents to take on and enhance their role as the most powerful agent of change for their children. Based on principles of transfer of control and parental modeling, the program teaches parents about effective cognitive-behavioural strategies for managing anxiety, and targets parenting behaviours and family accommodations implicated in the etiology of childhood anxiety (e.g., overprotectiveness, encouragement of avoidance). Thus, it equips parents to ‘coach’ their children in learning cognitive-behavioural strategies for managing anxiety while also focusing on parent–child relationship dynamics in the context of responding to children’s anxiety. Content covered in FLTP includes: psychoeducation about anxiety and parents’ potential role in the maintenance of children’s anxiety; promoting emotional resilience in children; modelling; the role of thoughts in anxiety and mental flexibility; avoidance and exposure; parental strategies for responding to children’s anxiety; and problem solving. Key concepts are incorporated in homework tasks. For example, cognitive restructuring is practiced at home where children are asked by their parents to generate as many interpretations as possible of ambiguous hypothetical child-focused situations.

Fear-less triple P group program

The standard FLTP group program consists of six, 90-min weekly sessions (approximately 9 h). Seven groups were run (4–8 families per group) and delivered at the Psychology Clinic (on weekday evenings) by two postgraduate clinical trainee psychologists, trained in the intervention. Supervision was provided by the first author, a licensed clinical psychologist and the lead author of the program. Each weekly session included in-session activities and homework tasks to apply the core concepts and strategies. Families attended an average of 5.4 of the 6 sessions (SD = 0.77). Of the 34 families randomized to the group condition, 29 had only the mother attend each session, two had only the father attend, two had both mother and father attend each session, and one had the mother attend all six sessions while the father also attended two sessions.

Fear-less triple P workshop

The FLTP workshop consists of a 1-day program (6 h). It was delivered at the Psychology Clinic by a licensed clinical psychologist and co-facilitated with one or two postgraduate clinical psychology trainees who received training in the intervention. Three workshops were delivered (on weekend days) with each one attended by between 7 and 17 families. Of the 39 families assigned to the workshop condition, 26 had only the mother attend the workshop, three had only fathers attend, and 10 had two parents in attendance.

Comparison of the two treatment modes

Both group and workshop formats provided the same core therapeutic concepts, examples and activities; with both incorporating didactic content delivery (via PPT slide presentation and participants’ workbooks). Following treatment, all families were contacted for a brief (15–20 min) phone call one-week post-intervention to give caregivers a chance to review the strategies and problem-solve any concerns arising since program completion. In both the group and workshop modalities, all sessions were recorded. Independent research assistants, who were blind to the study design, reviewed 20% of randomly chosen therapy session recordings for treatment adherence. Of the planned intervention content, 100% was covered as intended in both formats.

The delivery mode of intervention content was the main factor that distinguished the two modes. While both formats used the same PPT slide presentation and the parent workbook as their basis, families in the workshop condition had fewer opportunities to complete activities within the session (with only the most important activities and exercises done in-session) and instead were encouraged to work through these at home. Thus, while families in the workshop condition were engaged in some active learning activities, there was a heavier emphasis on didactic content presentation, with regular check-ins for questions. The conditions also differed in terms of the time allowed for in-group informal discussions. The six-week group program allowed opportunities for parents to not only network but also to discuss knowledge gained during previous weeks and share experiences, whereas the one-day workshop provided relatively little time for this to occur.

Data analyses

All analyses were conducted in IBM Statistics SPSS Version 25 [37]. Standard significance testing was used to explore all primary and secondary outcomes. Longitudinal, multi-level mixed models were used to explore whether SCAS-P total scores, SCAS-C total scores, FAD scores, sibling SCAS-P,Footnote 2 and parental DASS stress and anxiety scores significantly improved over time and whether there were differences in the changes over time between the treatment conditions. In each model, assessment time points (Level 1) were nested within participants (Level 2) and treatment condition was a Level 2 predictor.

Additionally, Pearson chi-square tests were used to determine whether the number of children who no longer met diagnostic criteria for their primary anxiety disorder or any anxiety disorder differed between the two conditions. Lastly, differences in parent satisfaction ratings at the post-treatment assessment and CGI scores at each of the follow-up assessments were assessed using independent samples t-tests.

Missing data at the follow-up assessment time points was accounted for using the multiple imputation procedure in SPSS for all analyses except for the longitudinal, multi-level models. In those analyses, missing data was accounted for by using restricted maximum likelihood estimation which allowed all data at each time point to be utilized without excluding participants who did not complete all measures or attend every time point.

Power analyses indicated that with α = 0.025 and power = 0.80, our acquired sample size was sufficient to detect moderate to large effect sizes, but not small effect sizes.