Predictors of outcomes following interdisciplinary acceptance and commitment therapy for chronic pain: Profiling psychological flexibility.

Background: Growing evidence demonstrates the benefit of acceptance and commitment therapy (ACT) for people with chronic pain. However, there remain people with chronic pain who do not benefit from ACT, and predicting treatment response is difficult.

Aims: This aim of this study was to investigate if baseline psychological flexibility (PF) profiles predict responses to an ACT-based pain management programme.

Methods: Data from 415 participants attending an interdisciplinary pain management programme were included. Participants completed measures of PF processes and outcomes pre- and post-treatment. Latent profile analysis was used to identify subgroups of participants based on their baseline PF scores. ANOVAs were conducted to compare subgroups of participants on outcome variables at baseline, and changes from pre- to post-treatment.

Results: Three subgroups of participants were identified: (a) low PF, (b) low openness and (c) high awareness and action. The three subgroups significantly differed on all outcome measures at pre-treatment, supporting the clinical relevance of these PF profiles. However, participants with different baseline PF profiles did not appear to differ in terms of changes in outcome variables.

Conclusions: People with chronic pain demonstrate different PF profiles, but appear to respond to ACT similarly regardless of these profiles. Future studies with a more individualized focus are needed to further understand which components of ACT work for whom on which outcome and how.

Significance: There remain people with chronic pain who do not benefit from acceptance and commitment therapy (ACT), and predicting treatment response is difficult. This is the first study to identify psychological flexibility (PF) profiles along multiple PF processes using latent class analysis, and the first longitudinal study to investigate PF profiles in relation to outcomes in ACT for chronic pain. The findings contribute to the understanding of theoretically consistent predictors of outcomes in ACT, which in turn can inform treatment development.