Background: In prospective experimental studies of neck pain patients, it is difficult to determine whether responses to sham acupuncture differ from responses to real acupuncture due to the heterogeneous methodologies in control/sham interventions. Here we aim to compare the specific and non-specific effects of electroacupuncture with four types of sham acupuncture.
Methods: In this double-blind sham-controlled study, we randomly assigned 175 patients with neck pain to receive 10 sessions of electroacupuncture, shallow puncture, non-acupoint deep puncture, non-acupoint shallow puncture or non-penetration acupuncture. We used the Northwick Park Neck Pain Questionnaire (NPQ) as our primary outcome, and Short-form McGill Pain Questionnaire, visual analogue scale (VAS) and Pain Threshold as secondary outcomes to measure the changes from baseline to a 3-month follow-up.
Results: All groups, except non-acupoint shallow puncture, had significant improvement in all outcome measurements. Electroacupuncture only showed superior improvements than the shallow puncture, non-acupoint shallow puncture and non-penetration groups when compared using the NPQ and VAS scale (P<0.001*). Interestingly, the non-acupoint shallow puncture produced even less placebo response than non-penetration acupuncture.
Conclusion: Our study demonstrates the high variability of placebo response among different types of sham controls depending on the depth of needle insertion and the puncture location. An important implication of our results is non-acupoint deep puncture produced similar analgesic effects as electroacupuncture. Our study may shed a new light on the predominant underlying mechanisms among different types of sham acupuncture controls, which can help with interpreting the effect of acupuncture in other studies.