Secondary analysis identifies possible mediators for chronic pain treatments in Veterans

Psychological interventions have reliable but modest effects on chronic pain outcomes, but our understanding of the mechanisms that underlie these effects remains limited. This paper presents the findings from a series of secondary analyses using data from a randomized clinical trial (clinicalTrials.gov, NCT02653664). Three hundred and twenty-eight Veterans of the US Armed Forces with chronic pain were randomized to receive clinical hypnosis, mindfulness meditation training, or pain education via 8 in-person group sessions. Of 17 candidate mediator variables assessed before and after treatment, 10 changed with treatment. Three of these were associated significantly with reductions in pain intensity and interference across all three treatment conditions: greater willingness to tolerate pain, greater engagement in valued activities despite pain, and reduced catastrophizing. A fourth candidate mediator assessed during treatment (working alliance) was significantly associated with reductions in pain intensity for those receiving clinical hypnosis. When comparing effects between treatments, catastrophizing appeared to play a larger role for the effects of mindfulness training on pain intensity and interference, and pain willingness appeared to play a larger role in the effect of therapeutic hypnosis on pain interference. Further research is needed to validate the reliability of the mediators identified in this study. If the findings from the current study replicate in other samples, they would support the importance of focusing treatment on thoughts about pain, pain avoidance, engagement in valued activities, and working alliance. PERSPECTIVE: Three psychological variables were identified as being possible mediators of the beneficial effects of mindfulness, clinical hypnosis, and pain education on pain. Additional research is needed to definitively test these variables as potential mediators of psychological pain treatments.