Abstract
BackgroundChronic 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).MethodsWe 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.DiscussionTo 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 registrationClinicalTrials.gov, NCT02503475. Registered on 15 July 15 2015. Retrospectively registered.
Highlights
Chronic low back pain (CLBP) is the most common chronic pain condition and is often resistant to conventional treatments
We propose to investigate central mechanisms of acupuncture in a clinical population suffering from CLBP
Our primary hypothesis is that the reduction in subjective rating of back pain bothersomeness in response to electroacupuncture will be mediated by reduction in ascending pain facilitation, which is measured by temporal summation
Summary
Chronic low back pain (CLBP) is the most common chronic pain condition and is often resistant to conventional treatments. Evidence suggests that pain regulatory mechanisms ( 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. The management of CLBP remains a significant challenge Conventional, anatomicallybased treatments such as surgical fusion and disc replacement often result in minimal or short-lived improvement [4]. The majority of studies on acupuncture for CLBP have used manual acupuncture with equivocal results [8] Both Haake (Germany) [9] and Cherkin (USA) [10] found that acupuncture led to greater improvement in pain and function compared with usual care (medical visits, physical therapy, and oral medications).
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