Pain acceptance and psychological inflexibility predict pain interference outcomes for persons with chronic pain receiving pain psychology.

OBJECTIVES: Awareness (being present), acceptance, and engagement (committed action) are three dimensions of psychological flexibility. Understanding these in the context of chronic pain may identify treatment targets to help refine individual treatment. Our objective was to test the predictive capacity of three dimensions within the psychological flexibility model on the longitudinal trajectory of pain interference. METHODS: Patients receiving pain psychology treatment at a pain management center participated in this pragmatic clinical longitudinal study (n=86 with at least three assessments; Mean age=51 years; Gender=60 females, 26 males). Measures included the Five Facet Mindfulness Questionnaire (FFMQ-SF); Chronic Pain Acceptance Questionnaire (CPAQ-8); Psychological Inflexibility in Pain Scale (PIPS-12); and Committed Action Questionnaire (CAQ-8). The dependent variable was the Patient Reported Outcomes Information System (PROMIS) Pain Interference (PI). We used latent growth modelling to analyze scores assessed within 180 days of patient care. RESULTS: Psychological inflexibility (PIPS-12) and pain acceptance (CPAQ-8) measured at baseline predicted PI outcomes (n=86). PIPS-12 showed a direct relationship with pain interference (PI), where higher PIPS-12 scores predicted significantly higher PI mean scores on average across the study period (ρ=0.422, r2=0.382) but also predicted significantly greater decreases in PI across time (ρ=-0.489, r2=0.123). Higher CPAQ-8 scores predicted significantly lower PI mean scores on average across the study period (ρ=-0.478, r2=0.453) but also significantly smaller decreases in PI across time (ρ=0.495, r2=0.076). Awareness (FFMQ-SF) and engagement (CAQ-8) were not predictive of PI outcomes. CONCLUSIONS: Patients who entered pain psychology treatment with lower pain acceptance and higher psychological inflexibility showed the largest reductions in pain interference across time. These results contribute towards a novel prognostic understanding of the predictive roles of an enhancing dimension and limiting dimension of psychological flexibility.

Central mechanisms of real and sham electroacupuncture in the treatment of chronic low back pain: study protocol for a randomized, placebo-controlled clinical trial.

BACKGROUND: Chronic low back pain (CLBP) is the most common chronic pain condition and is often resistant to conventional treatments. Acupuncture is a popular alternative for treating CLBP but its mechanisms of action remain poorly understood. Evidence suggests that pain regulatory mechanisms (particularly the ascending and secondarily the descending pain modulatory pathways) and psychological mechanisms (e.g., expectations, pain catastrophizing and self-efficacy) may be involved in the pathogenesis of CLBP and its response to treatments. We will examine these mechanisms in the treatment of CLBP by electroacupuncture (EA). METHODS: We present the aims and methods of a placebo-controlled, participant-blinded and assessor-blinded mechanistic study. Adult patients with CLBP will be randomized to receiving 16 sessions of real (active) or sham (placebo) EA over the course of 8 weeks. The primary pain regulatory measure for which the study was powered is temporal summation (TS), which approximates ascending pain facilitation. Conditioned pain modulation (CPM), representing a descending pain modulatory pathway, will be our secondary pain regulatory measure. The primary psychological measure is expectations of benefit, and the secondary psychological measures are pain catastrophizing and self-efficacy in managing pain. Main clinical outcomes are back pain bothersomeness on a 0-100 visual analog scale (primary), Roland Morris Disability Questionnaire (secondary), and relevant items from the National Institutes of Health (NIH) Patient-Reported Outcome Measures Information System (secondary). We hypothesize that compared to sham, real EA will lead to greater reduction in TS after 8 treatment sessions (4 weeks); and that reduction in TS (and secondarily, increase in CPM) after 8 treatment sessions will mediate reduction in back pain bothersomeness from baseline to week 10 (clinical response) to EA. We also hypothesize that the three psychological factors are moderators of clinical response. With 100 treatment completers, the study is designed to have 80% power to detect a medium-sized between-group effect (d = 0.5) on temporal summation. DISCUSSION: To the best of our knowledge, this is the first appropriately powered, placebo-controlled clinical trial evaluating mechanisms of EA in the treatment of CLBP. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02503475 . Registered on 15 July 15 2015. Retrospectively registered.