Analgesic effect of acupuncture needle penetration: a double-blind crossover study.

BACKGROUND: Double-blind evaluation of acupuncture treatment has not previously been reported. We investigated the possible advantage of analgesic effects of needle penetration compared with skin pressure using non-penetrating needles in a double-blind study. METHODS: We conducted a double-blind crossover study of penetrating and non-penetrating (placebo) acupuncture trials. We recruited 56 healthy volunteers. They received painful electrical stimulation in the forearm for 1 minute before and immediately after and 10 minutes after each needle insertion to the LI-4 point, as well as 1 minute before, immediately after, and 10, 20, 30 and 40 minutes after the removal of the needle, which had remained in place for 20 minutes. After each application of electrical stimulation, the subjects rated the pain intensity using a numeric rating scale (0-150) comparing it with the baseline pain intensity (100) before the needle was applied. Pain from skin penetration and deep, dull pain (de qi) associated with needle application, which is considered essential for achieving successful acupuncture analgesia, were also recorded. RESULTS: We found no significant difference in analgesic effects between the penetrating and non-penetrating needle trials. In addition, no significant correlation was found between analgesic effect and de qi. A significant analgesic effect was observed during needle application and immediately after needle removal for both the penetrating and non-penetrating needle trials when compared with the no-acupuncture control condition (penetrating v. control: immediately, 10 minutes and 20 minutes after needle insertion [p < 0.001 for each] and immediately, 10 minutes and 20 minutes after needle removal [p < 0.050] for each; non-penetrating v. control: immediately, 10 minutes and 20 minutes after needle insertion [p < 0.001 for each] and immediately after needle removal [p = 0.010]). INTERPRETATION: Needle penetration did not confer a specific analgesic advantage over non-penetrating (placebo) needle application.