The specific effect of systematic exposure in irritable bowel syndrome: complier average causal effect analysis using growth mixture modeling.

BACKGROUND: We reanalyzed data from a previously published randomized component study that aimed to test the incremental effect of systematic exposure in an internet-delivered cognitive behavioral treatment (ICBT) for irritable bowel syndrome (IBS). METHODS: Three hundred and nine individuals with IBS were randomly assigned to either the full treatment protocol (experimental condition) or the same treatment protocol without systematic exposure (control). Participants were assessed weekly for IBS symptoms over the active treatment phase. We used a complier average causal effect (CACE) analysis, in the growth mixture modeling framework, to (1) examine the specific effect of exposure among those who received the intervention (i.e. compliers), and (2) explore the associations of pre-treatment patient characteristics with compliance status and outcome changes. RESULTS: Fifty-five per cent of those assigned to the experimental condition were classified as compliers. The CACE analysis that took into account compliance status demonstrated that the magnitude of the incremental effect of systematic exposure on IBS symptoms was larger than the effect observed in an intention-to-treat analysis that ignored compliance status (d = 0.81 v. d = 0.44). Patients with university education showed more improvement during the exposure phase of the treatment. Pre-treatment patient characteristics did not predict compliance status. CONCLUSIONS: The effect of systematic exposure on IBS symptoms is of substantial magnitude among those individuals who actually receive the intervention (CACE). Studying the subsample of individuals who discontinue treatment prematurely and tailoring interventions to improve compliance may increase overall improvement rates in ICBT for IBS.

Processes of change in Acceptance and Commitment Therapy and Applied Relaxation for long-standing pain.

BACKGROUND: The utility of cognitive behavioural (CB) interventions for chronic pain has been supported in numerous studies. This includes Acceptance and Commitment Therapy (ACT), which has gained increased empirical support. Previous research suggests that improvements in pain catastrophizing and psychological inflexibility are related to improvements in treatment outcome in this type of treatment. Although a few studies have evaluated processes of change in CB-interventions, there is a particular need for mediation analyses that use multiple assessments to model change in mediators and outcome over time, and that incorporate the specified timeline between mediator and outcome in the data analytic model. METHODS: This study used session-to-session assessments to evaluate if psychological inflexibility, catastrophizing, and pain intensity mediated the effects of treatment on pain interference. Analyses were based on data from a previously conducted randomized controlled trial (n = 60) evaluating the efficacy of ACT and Applied Relaxation (AR). A moderated mediation model based on linear mixed models was used to analyse the data. RESULTS: Neither catastrophizing nor pain intensity mediated changes in pain interference for any of the treatments. In contrast, psychological inflexibility mediated effects on outcome in ACT but not in AR. CONCLUSIONS: Results add to previous findings illustrating the role of psychological inflexibility as a mediator in ACT.

Therapist-assisted Internet-delivered cognitive behavior therapy for depression and anxiety: translating evidence into clinical practice.

This dissemination study examined the effectiveness of therapist-assisted Internet-delivered Cognitive Behavior Therapy (ICBT) when offered in clinical practice. A centralized unit screened and coordinated ICBT delivered by newly trained therapists working in six geographically dispersed clinical settings. Using an open trial design, 221 patients were offered 12 modules of ICBT for symptoms of generalized anxiety (n=112), depression (n=83), or panic (n=26). At baseline, midpoint and post-treatment, patients completed self-report measures. On average, patients completed 8 of 12 modules. Latent growth curve modeling identified significant reductions in depression, anxiety, stress and impairment (d=.65-.78), and improvements in quality of life (d=.48-.66). Improvements in primary symptoms were large (d=.91-1.25). Overall, therapist-assisted ICBT was effective when coordinated across settings in clinical practice, but further attention should be given to strategies to improve completion of treatment modules.