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
Introduction
Chronic low back pain (LBP) that is associated with high pain-related fear is disabling (Vlaeyen, Crombez, & Linton, 2016), as indexed by its impacts on work (Coggon et al., 2013), physical activity (Martel, Thibault, & Sullivan, 2010) and social participation (Hoogendoorn, van Poppel, Bongers, Koes, & Bouter, 2000). This high fear group often presents with changes across multiple interacting factors, including cognitive (Bunzli, Smith, Schutze, & O'Sullivan, 2015), emotional (Glombiewski et al., 2015), behavioural (Geisser, Haig, Wallbom, & Wiggert, 2004; Karayannis, Smeets, van den Hoorn, & Hodges, 2013; Thomas & France, 2007), lifestyle, social (Bunzli, Watkins, Smith, Schutze, & O'Sullivan, 2013), and pain processing factors (O'Sullivan et al., 2014; Rabey, Slater, O'Sullivan, Beales, & Smith, 2015). The interplay of these factors is likely to vary for each person, and fluctuate over time (Kongsted, Kent, Axen, Downie, & Dunn, 2016; O'Sullivan, Caneiro, O'Keeffe, & O'Sullivan, 2016).
Therefore, understanding how changes in these factors relate to fear and disability reduction over the course of an intervention may provide important insight into processes involved in behavioural change in people with high levels of pain-related fear. The traditional biomedical understanding of therapeutic change is that improvement occurs in a sequential and gradual manner over the treatment period (Brodal, 2017; George, 2017; Vlaeyen, de Jong, Geilen, Heuts, & van Breukelen, 2001). Mediation analysis provides a useful method to investigate how multiple factors relate to the outcome over time. Mediators are defined statistically as factors that change because of an intervention, and that correlate with changes in the selected outcome (Lee et al., 2017). This can provide information regarding factors that contributed the most to the treatment effect. In clinically based research, randomised controlled trials (RCTs) are the most common framework for analysis of mediators of the tested treatment effect (Mansell, Kamper, & Kent, 2013). However, they require large samples and expenditure which is often a limiting factor in the number of variables and timepoints that can be captured. Although this is not an inherent rule, with many studies often assessing a single mediator at a single timepoint during the intervention (Mansell, Hill, Main, Vowles, & van der Windt, 2016). This is an obvious limitation when investigating complex problems such as chronic LBP because the time course of the mediator-outcome relationship is likely to vary between individuals. Considering that RCTs often only capture a limited number of timepoints, their design may therefore be insensitive to the timing of mediator and outcome change in relation to the intervention (Riley & Gaynor, 2014), an important limitation in establishing mediation (Kazdin, 2007).
In contrast to mediation analysis conducted in RCTs, single-case experimental design studies (SCEDs) facilitate detailed assessment at frequent timepoints, capturing multiple potential factors related to an individual's response to treatment (Borckardt et al., 2008; Gaynor & Harris, 2008; Morley, 2018; Morley, Vlaeyen, & Linton, 2015). An SCED is an intensive, prospective and controlled study of the individual, using each person as his/her own control to enhance reliability (Morley, 2018; Morley et al., 2015). SCEDs enable the adoption of a complex system perspective, which accommodates interaction of multiple factors and within-person temporal variations, thereby reflecting individuality in the evaluation of the therapeutic change process. Well-designed SCEDs, that include repeated measures and a stable baseline, can answer questions about improvement and the change process, to unravel the anatomy of therapeutic change (Borckardt et al., 2008).
Considering the need to understand how change unfolds at an individual level, we employed a SCED. The primary aim was to evaluate how measures of potential mediators related to outcome (disability) over time during a behavioural intervention for people with chronic LBP and high fear. A second aim was to evaluate whether the change (sequential or simultaneous) in mediators and disability occurred at the same timepoint during the intervention period for all individuals. A pre-requisite for evaluating the process of change was that the intervention changed both the outcome and proposed mediators. The intervention was an individualised, exposure-based, behavioural approach for the management of people with chronic LBP, called Cognitive Functional Therapy (CFT) (O'Sullivan et al., 2018). The efficacy of CFT has been tested in an RCT (Bunzli, McEvoy, Dankaerts, O'Sullivan, & O'Sullivan, 2016; Caneiro, Smith, Rabey, Moseley, & O'Sullivan, 2017; O'Sullivan, Dankaerts, O'Sullivan, & O'Sullivan, 2015; Vibe Fersum, O'Sullivan, Skouen, Smith, & Kvale, 2013), which showed it to be superior to standard physiotherapy, demonstrating large effect sizes for reductions in pain-related fear, pain intensity and disability in people with chronic LBP and moderate disability. In a recent case series (Bunzli et al., 2016; Caneiro, Smith, et al., 2017; O'Sullivan et al., 2015; Vibe Fersum et al., 2013), CFT was also shown to be effective in decreasing disability, pain and fear, and increasing pain-related self-efficacy in people with chronic LBP waitlisted at a pain clinic. However, CFT had not been specifically tested in people with chronic LBP and high pain-related fear, and the process by which reduction in disability is mediated had not been quantitatively investigated (Bunzli et al., 2016). CFT is informed by the fear-avoidance model (Vlaeyen & Linton, 2000) which is the prevailing model of the development of pain-related disability. It proposes that pain-related cognitive and emotional responses can drive unhelpful behavioural responses that in turn lead to disability. Based on (i) the fear-avoidance model (Vlaeyen & Linton, 2000); (ii) prior research on mediators of treatment effect in people with back pain (Lee et al., 2015; Leeuw et al., 2008; Mansell, Hill, Main, Von Korff, & van der Windt, 2017), and (iii) the hypothesised mechanisms of action of CFT (Bunzli et al., 2016; Caneiro, Smith, et al., 2017; O'Sullivan et al., 2015; Vibe Fersum et al., 2013), it was hypothesised that pain intensity, pain controllability, fear, emotional distress and sleep would mediate reduction in disability.
Section snippets
Methods
This study complies with the Single-Case Reporting guideline In BEhavioural interventions (SCRIBE) 2016 (Tate et al., 2017).
Participant characteristics
Four people (one male) with chronic LBP and high pain-related fear participated– see Table 1 for detailed characteristics of the participants, and Table 2 for details at baseline (Weeks 1 and 8).
All participants showed a stable baseline for the measures of outcome and proposed mediators. All participants completed the treatment and all assessments across the three phases of the study. There were no adverse events, and treatment compliance was high across all participants (see Table 2 for
Discussion
The primary aim of this study was to evaluate how potential mediators relate to disability over time, during a behavioural intervention (CFT) in four people with chronic LBP and high pain-related fear of bending and lifting. A second aim was to evaluate whether the change (sequential or simultaneous) in mediators and disability occurred at the same timepoint during the intervention period for all individuals.
First, the results verified that reductions in disability and proposed mediators (pain,
Conclusion
This single-case experimental design study demonstrated the interplay of factors associated with treatment response, highlighting ‘how change unfolded’ uniquely for each individual. Changes in pain, pain controllability, and fear occurred concomitantly to changes in disability, suggesting a disruption in the person's entire pain schema. The findings that factors underpinning treatment response and the outcome changed simultaneously, challenge the traditional understanding of therapeutic change.
Data statement
Data for the four participants of this study is embedded in the manuscript and individually presented either in a graphic or table format.
Acknowledgements
The authors would like to acknowledge the participants for devoting their time and efforts during the process of this study.
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