Temporal Summation but not Expectations of Pain Relief Predict Response to Acupuncture Treatment in Fibromyalgia

Abstract

Fibromyalgia (FM) is a common chronic pain condition for which acupuncture treatment is increasingly utilized. However, there is no universally accepted measure to predict whether a specific patient will benefit from acupuncture. This is a single center, single-blind, sham-controlled, randomized, non-crossover, longitudinal trial of 76 subjects with FM, assigned to either electroacupuncture or a placebo control, mock laser acupuncture. Outcome measures included: clinical pain severity (Brief Pain Inventory, BPI), degree of nociplastic pain (Fibromyalgia Survey Questionnaire, FSQ), and pressure pain tolerance. Baseline measures of temporal summation of pain and expectations for treatment relief were used as predictors. Individuals in both treatment groups experienced significant reductions in BPI (electroacupuncture: p<0.001; mock laser: p=0.018) and FSQ (electroacupuncture: p=0.032; mock laser: p=0.002) after treatment; however, neither group showed a significant increase in pressure pain tolerance. Lower temporal summation at baseline was correlated with greater post-treatment improvement in BPI in the electroacupuncture group (rho=0.389, p=0.025) but not in the mock laser group (rho=-0.272, p=0.109). Lower baseline temporal summation was correlated with greater decreases in pressure pain tolerance following electroacupuncture (rho=0.400, p=0.040), whereas the opposite was seen for mock laser (rho=-0.562, p=0.001). Treatment expectancy at baseline was not correlated with any outcome after electroacupuncture or mock laser treatments. Our results support using a quantitative sensory testing metric, temporal summation of pain, but not expectations, to predict analgesia following acupuncture treatment for pain. Clinical trial registrationRegistered under ClinicalTrials.gov identifier NCT02064296. PerspectiveA randomized study of acupuncture in fibromyalgia found baseline temporal summation, but not expectations of pain relief, to be predictive of treatment response.