Examining what factors mediate treatment effect in chronic low back pain: A mediation analysis of a Cognitive Functional Therapy clinical trial

Abstract

Background Cognitive Functional Therapy (CFT) is a physiotherapist‐led individualized intervention for people with people with non‐specific chronic low back pain (CLBP), involving biopsychosocial pain education, graded movement exposure and lifestyle coaching. Methods A multicentre randomized controlled trial (RCT), including 206 participants with CLBP in Ireland, supported CFT’s effectiveness for reducing disability, but not pain, compared to a group exercise and education intervention. In this study, causal mediation analysis was used to determine whether the effect of CFT on disability and the lack of effect on pain (relative to a group exercise and education intervention) is mediated by certain psychological and lifestyle factors. Hypothesized mediators measured were pain self‐efficacy, stress, fear of physical activity, coping, depression, anxiety and sleep, at 6 months. The outcomes measured were functional disability and pain intensity at 12 months. Results This causal mediation study shows that the majority of benefit of CFT (relative to a group exercise and education intervention) for disability is due to increasing pain self‐efficacy. Conclusion Conclusion: CFT did not improve the majority of the hypothesized mediators (stress, fear of physical activity, coping, depression, anxiety and sleep) and these mediators were not associated with either disability or pain. Unfortunately, the proportion of missing data in this study is substantial and these findings can only be considered hypothesis‐generating. Therefore, future research should examine replicating the results of this study to verify the role of self‐efficacy and other proposed mediators (e.g. stress, coping, sleep, fear) on clinical outcomes. Significance An exploration of seven potential mediators was undertaken to determine the effect of Cognitive Functional Therapy (CFT) on disability and pain intensity in individuals with chronic low back pain compared to a group exercise and education intervention. CFT improved pain self‐efficacy, which was associated with disability and pain outcomes. CFT did not improve the other six potential mediators (stress, fear of physical activity, coping, depression, anxiety and sleep) and these were not associated with disability or pain. The proportion of missing data in this study is substantial and these findings should be considered hypothesis‐generating only.

Using Mediation Analysis to Understand How Treatments for Paediatric Pain Work: A Systematic Review and Recommendations for Future Research

“…That no studies in this review investigated mechanisms of failed interventions is likely influenced by historical perspectives on mediation whereby a statistically significant treatment effect was required to proceed with mediation analysis [20]. However, recent research has shown this requirement to be unnecessary, as indirect effects can be present in the absence of direct effects [13,38,49]. Therefore, mediation analysis of ineffective treatments is encouraged [10,50,51] and could benefit the paediatric pain field.…”

Mechanisms of recovery after neck‐specific or general exercises in patients with cervical radiculopathy

“…To date, no studies to our knowledge have investigated the mechanism(s) of action (if any) which different exercise programs act upon to improve recovery in individuals with CR. In other spinal musculoskeletal pain disorders, different exercise programs have been shown to reduce pain-related disability by influencing catastrophizing (Hall et al, 2016;Smeets et al, 2006) and self-efficacy levels (Liew et al, 2019;O'Neill et al, 2020;Sherman et al, 2013).…”

“…To understand the mechanisms of action of different treatments, structured equations modelling (SEM) (Fordham et al, 2017;Mansell et al, 2016) and linear regression models (Hall et al, 2016;O'Neill et al, 2020) have been used. Both methods can be seen as particular cases of Bayesian Networks (BNs) (Nagarajan et al, 2013), a probabilistic graphical modelling approach used increasingly in the medical field (Farmer, 2014;Takenaka & Aono, 2017;Thanathornwong, 2018).…”

Assessment of measurement properties of the Brazilian-Portuguese version of the low back activity confidence scale (LoBACS) in patients with chronic low back pain

“…Recently, some studies have evaluated self-efficacy as a treatment method for patients with LBP [ 13 – 15 ]. Khodadad et al .…”