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Table 1 Similarities and differences between the current trial (BIP TIC RCT) and the parallel Online Remote Behavioural Intervention for Tics (ORBIT) trial

From: Efficacy and cost-effectiveness of therapist-guided internet-delivered behaviour therapy for children and adolescents with Tourette syndrome: study protocol for a single-blind randomised controlled trial

Objectives

Both studies have identical main objectives (efficacy, durability, and cost-effectiveness). The ORBIT study further includes objectives on optimising the design and delivery of BIP TIC, undertaking an internal pilot, and conducting a process evaluation.

Study design and setting

Both studies are single-blind, parallel group, randomised controlled superiority trials, comprising two 10- to 12-week interventions. The primary endpoint of the BIP TIC RCT is 3 months after the end of treatment, whereas the primary endpoint of the ORBIT study is circa post-treatment (referred to as 3 months post-randomisation in the ORBIT protocol). The BIP TIC RCT includes assessment points at post-treatment, 3FU (primary endpoint), 6FU, and 12FU, while the ORBIT study includes assessment points at circa post-treatment (primary endpoint), 3FU, 9FU, and 15FU. Both studies maintain per protocol parallel group follow-up to circa 3 months post-treatment. After this point, participants in both trials may use alternative treatments for their tics. Both studies recruit nationally but the BIP TIC RCT is run from a single site (Stockholm), whereas the ORBIT study has two research sites (Nottingham and London).

Participants

Both studies recruit children and adolescents (9-17 years) with TS or CTD. There are some slight differences in the eligibility criteria, the primary being that the ORBIT study does not exclude participants with autism spectrum disorder or organic brain disorder.

Randomisation

Both studies randomise participants at a 1:1 ratio using block randomisation with varying block sizes. The ORBIT study further uses stratification by study site.

Interventions

Both studies evaluate the same two interventions (BIP TIC and the comparator), delivered through the same IBT platform (BIP). All chapters share the same overall content and are presented in the same order. Due to translation (from Swedish to English and back) and slight cultural adaptations, the exact content (e.g. wording, illustrations, and video scripts) may differ somewhat between the two studies. The key homework assignments are identical in both studies.

Outcome measures

Both studies share the same primary outcome measure (tic severity measured by the YGTSS-TTSS), and the same definition of treatment response (“Very much improved” or “Much improved” on the CGI-I). Several secondary measures such as the YGTSS Impairment, PTQ, C&A-GTS-QOL, and CGAS are identical, while other secondary measures differ between the studies. Cost measures differ across the two trials.

Blinding

Both studies use assessors who are blind to treatment allocation at all assessment points. Both studies take extensive measures to preserve blindness integrity. Statistical analyses are performed blindly.

Power analysis

Both studies aim to recruit 220 participants. The power calculations were performed using median-based methods (BIP TIC RCT) vs mean-based methods (ORBIT).

Statistical analyses

The statistical analyses of the primary outcome will be performed using a linear quantile mixed model, supplemented by a linear mixed model (BIP TIC RCT) vs linear regression (ORBIT).

Health economic evaluation

Both trials will perform a cost-effectiveness analysis (disorder-specific) and a cost-utility analysis (generic analysis with generic units [QALYs]). The outcomes for the disorder-specific analysis are the CGI-I-derived responder rate (BIP TIC RCT) and point change in YGTSS (ORBIT). In the BIP TIC RCT, QALYs are estimated by mapping the KIDSCREEN-10 onto CHU9D utilities, while ORBIT uses CHU9D directly. Data on healthcare and societal resource use are collected through the TiC-P (BIP TIC RCT) and the CSRI and CA-SUS (ORBIT).

  1. Abbreviations: 3FU-15FU assessment points 3–15 months post-treatment, BIP Barninternetprojektet (Swedish for “The Child Internet Project”), BIP TIC therapist-guided internet-delivered behaviour therapy (exposure with response prevention) for children and adolescents with Tourette syndrome or chronic tic disorder, C&A-GTS-QOL Child and Adolescent Gilles de la Tourette Syndrome–Quality of life scale, CA-SUS Child and Adolescent Service Use Schedule, CGAS Children’s Global Assessment Scale, CGI-I Clinical Global Impression – Improvement scale, CHU9D Child Health Utility 9 Dimensions, comparator therapist-guided internet-delivered education for children and adolescents with Tourette syndrome or chronic tic disorder, CSRI Client Service Receipt Inventory, IBT internet-delivered behaviour therapy, ORBIT Online Remote Behavioural Intervention for Tics, post-treatment assessment point directly after the end of treatment, PTQ Parent Tic Questionnaire, TiC-P Trimbos/iMTA questionnaire for costs associated with psychiatric illness, YGTSS Yale Global Tic Severity Scale, QALY quality-adjusted life year, YGTSS-TTSS Yale Global Tic Severity Scale – Total Tic Severity Score