How does change unfold? an evaluation of the process of change in four people with chronic low back pain and high pain-related fear managed with Cognitive Functional Therapy: A replicated single-case experimental design study

Purpose: To understand the process of change at an individual level, this study used a single-case experimental design to evaluate how change in potential mediators related to change in disability over time, during an exposure-based behavioural intervention in four people with chronic low back pain and high pain-related fear. A second aim was to evaluate whether the change (sequential or simultaneous) in mediators and disability oc-curred at the same timepoint for all individuals. Results: For all participants, visual and statistical analyses indicated that changes in disability and proposed mediators were clearly related to the commencement of Cognitive Functional Therapy. This was supported by standard outcome assessments at pre-post timepoints. Cross-lag correlation analysis determined that, for all participants, most of the proposed mediators (pain intensity, pain controllability, and fear) were most strongly associated with disability at lag zero, suggesting that mediators changed concomitantly and not before disability. Importantly, these changes occurred at different rates and patterns for different individuals, highlighting the individual temporal variability of change. Conclusion: This study demonstrated the interplay of factors associated with treatment response, highlighting `how change unfolded' uniquely for each individual. The findings that factors underpinning treatment response and the outcome changed simultaneously, challenge the traditional understanding of therapeutic change.