Pressure Pain Sensitivity Predicts Response to Acupuncture in Fibromyalgia

Pressure pain sensitivity is differentially linked to response to sham vs verum acupuncture in patients with fibromyalgia, according to a post-hoc analysis.¹

Due to the scarcity of effective treatments for pain in fibromyalgia, up to 20% of patients seek alternative therapies such as acupuncture.^2,3 Findings regarding the efficacy of this approach for fibromyalgia have been unclear, with some studies showing improvement in symptoms and others showing minimal or no improvement compared with placebo.^4-6

However, those mixed results could be due to the lack of an adequate form of sham acupuncture for placebo-controlled trials, and most studies on the topic did not evaluate participants’ response to needling sensations and experimental pain sensitivity. “This may be critical as the level of sensation patients experience during needling may factor into treatment response…. any analgesic effect from strong needling may be masked, as the needling sensation itself may counteract the analgesic effects of acupuncture,” wrote the investigators in the current study.

They further analyzed findings from their previous research to determine whether varying levels of baseline pressure pain sensitivity would differentially affect participants’ analgesic response to 18 sessions of verum (n=59) vs sham (n=55) acupuncture (average age, 48.3; 91.8% women; 87.7% white).⁷ With verum acupuncture, needles were placed in established locations according to traditional Chinese medicine, while in the sham condition, needles were placed in nontraditional locations.

Pressure pain sensitivity at the thumbnail was measured by quantitative sensory testing. Pain intensity was assessed using a 0 to 100 visual analog scale (0 = no pain; 100 = worst pain imaginable), and the intensity of needling sensations were self-reported via questionnaire after each session. 

Patients with higher pressure pain thresholds experienced greater pain reduction after verum acupuncture (a unit increase in pain threshold leads to pain reduction of 0.841 [VAS] per unit cumulative acupuncture dose [SE = 0.304, P =.006]), but minimal or no response to sham acupuncture. Patients with lower thresholds experienced greater pain reduction after sham acupuncture (a unit decrease in pain threshold shows a trend for pain reduction of 0.428 [VAS] per unit cumulative dose [SE = 0.229, P =.062]), and increased pain following verum acupuncture. Sensitivity to acupuncture needling showed similar patterns. 

“Our results suggest that pressure pain sensitivity can be used to help differentially predict treatment response to both sham and verum acupuncture,” wrote the authors. This variable and sensitivity to needling sensations may have been confounding factors in prior research, leading to an inaccurate perception of the efficacy of acupuncture in fibromyalgia.

Summary and Clinical Applicability

Pressure pain sensitivity threshold may help predict efficacy of acupuncture in certain patients with fibromyalgia, and could help to inform personalized treatment approaches. 

Limitations

The small sample size, large percentage of women and white participants, and the presence of fibromyalgia in all participants may limit the generalizability of the findings.

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References

1. Zucker NA, Tsodikov A, Mist SD, Cina S, Napadow V, Harris RE. Evoked pressure pain sensitivity is associated with differential analgesic response to verum and sham acupuncture in fibromyalgia. Pain Med. 2017. doi:10.1093/pm/pnx001
2. Bennett RM, Jones J, Turk DC, Russell IJ, Matallana L. An internet survey of 2,596 people with fibromyalgia. BMC Musculoskelet Disord. 2007; 8:27. doi:10.1186/1471-2474-8-27
3. Deare JC, Zheng Z, Xue CC, et al. Acupuncture for treating fibromyalgia. Cochrane Database Syst Rev. 2013; (5):CD007070. doi:10.1002/14651858.CD007070.pub2
4. Langhorst J, Klose P, Musial F, Irnich D, Hauser W. Efficacy of acupuncture in fibromyalgia syndrome—a systematic review with a metaanalysis of controlled clinical trials. Rheumatology. 2010; 49(4):778–788. doi:10.1093/rheumatology/kep439
5. Yang B, Yi G, Hong W, et al. Efficacy of acupuncture on fibromyalgia syndrome: A meta-analysis. J Tradit Chin Med. 2014; 34(4):381–391.
6. Lauche R, Cramer H, Hauser W, Dobos G, € Langhorst J. A systematic overview of reviews for complementary and alternative therapies in the treatment of the fibromyalgia syndrome. Evid Based Complement Alternat Med. 2015; 2015:610615. doi:10.1155/2015/610615
7. Harte SE, Clauw DJ, Napadow V, Harris RE. Pressure pain sensitivity and insular combined glutamate and Glutamine (Glx) are associated with subsequent clinical response to sham but not traditional acupuncture in patients who have chronic pain. Med Acupunct. 2013; 25(2):154–160. doi:10.1089/acu.2013.0965