Improving access to behaviour therapy for young people with Tourette syndrome

Abstract

Tourette syndrome (TS) and Chronic Tic Disorder (CTD) are childhood-onset neurodevelopmental disorders characterised by motor and vocal tics. Treatment guidelines recommend behaviour therapy (BT) as the first-line treatment for TS/CTD, but availability is generally low. The overall aim of this thesis was to promote the dissemination of BT among young individuals with TS/CTD.

Study I was a longitudinal naturalistic study at a paediatric TS/CTD specialist clinic. Seventy-four children and adolescents with TS or CTD were recruited and received regular face-to-face BT at the clinic, either exposure and response prevention (ERP; n=46), habit reversal training (HRT; n=14) or various combinations of psychoeducation, ERP, and HRT (n=14). For the 74 participants, tic severity – as measured by the Total Tic Severity Score (TTSS) of the clinician-rated interview Yale Global Tic Severity Scale (YGTSS) – improved from baseline to the posttreatment assessment point with a large within-group effect size (d=1.03). Thirty-eight participants (57%) were classified as treatment responders at post-treatment. The treatment effects further improved at a 12-month follow-up (12FU). The study concluded that BT for young people with TS/CTD delivered in a naturalistic specialist clinical setting is effective at both short- and long-term, with effects comparable to those in RCTs.

Despite the promising results of Study I, few young individuals with TS/CTD have access to such specialised clinical services. To improve accessibility, we developed two therapist-supported, internet-delivered BT programmes based on ERP and HRT (named BIP TIC ERP and BIP TIC HRT, respectively). Next, we evaluated the feasibility, credibility, acceptability, preliminary efficacy, and preliminary durability of the two interventions in a pilot randomised controlled trial (RCT). Twenty-three children and adolescents with TS or CTD were randomised to BIP TIC ERP (n=12) or BIP TIC HRT (n=11). Tic severity, as measured by the primary outcome measure YGTSS-TTSS, improved significantly between baseline and the 3-month follow-up (3FU; the primary endpoint) in the BIP TIC ERP group (d=1.12), but not in the BIP TIC HRT group (d=0.50). Nine participants (75%) in BIP TIC ERP and 6 participants (55%) in BIP TIC HRT were classified as treatment responders at the primary endpoint. The effects of BIP TIC ERP were further maintained at a 12FU. The average therapist support time was 25 minutes per participant and week, compared to 60 minutes in face-to-face BT. Both interventions were concluded as feasible, acceptable, and safe to deliver, but due to its preliminary efficacy, BIP TIC ERP was chosen to be further examined in a larger study.

Study III, a fully powered superiority RCT, aimed to evaluate the clinical efficacy of BIP TIC ERP compared with an active control intervention, as well as to conduct a health economic evaluation. Two-hundred and twenty-one children and adolescents with TS or CTD were recruited and randomised to BIP TIC ERP (n=111) or therapist-supported, internet-delivered education (the comparator; n=110). Both groups showed similar tic severity improvements over time, as measured by the primary outcome measure YGTSS-TTSS. No interaction effect of group and time was identified on the YGTSS-TTSS at the primary endpoint (the 3FU), but significantly more participants responded to BIP TIC ERP (n=51; 47%) than to the comparator (n=31; 29%). The average therapist support time per participant and week was 19.05 minutes for the BIP TIC ERP group and 16.55 minutes for the comparator. Overall, the BIP TIC ERP group showed small non-significant gains in quality-adjusted life years (QALYs) at non-significantly larger costs. For BIP TIC ERP, the incremental cost per QALY gained was below a willingness-to-pay threshold of 79 000 USD used in Swedish society, at which this intervention had a 66-76% probability of being cost-effective. In this study, both interventions were associated with clinically meaningful tic severity improvements, but BIP TIC ERP showed higher treatment response rates, greater treatment satisfaction, and appears costeffective, indicating that this intervention is more suitable for implementation.

The thesis concludes that face-to-face BT for young individuals with TS/CTD can be successfully implemented into a specialist outpatient clinic, with effects comparable to those shown in RCTs. To increase availability further, BT may also be delivered remotely. A dissemination of the BIP TIC ERP intervention into regular healthcare would enable nationwide access to BT for children and adolescents with TS/CTD.