Is electroacupuncture a placebo in experimental tourniquet pain?

Acupuncture has lately been discussed to be a powerful placebo. The standard paradigm in experimental pain/placebo research is experimental ischemic pain (submaximal effort tourniquet technique=SETT). The aim of this study was to directly compare the effect of electroacupuncture to pharmacological interventions in a well-established, opiate-sensitive, standardized, experimental pain paradigm. Accordingly, there was no sham acupuncture condition. The effects of a placebo pill, a non-steroidal analgesic (Ibuprofen: 400 mg), an opiate (Tramadol: 50 mg) and electroacupuncture on the SETT were compared to non-treatment control. Methods In total, 125 healthy young men (mean age: 24.44±4.46) were randomized to 5 groups (non-treatment control, placebo pill, Ibuprofen, Tramadol, and electroacupuncture). Baseline was measured at day 1 and treatment on day 2 in a double-blind design for the pharmacological conditions. SETT was performed on the non-dominant arm with 250 mmHg cuff pressure and time was limited to 30 min or a pain rating of 10 (Scale 0–10). Subjects were prompted every 3 min to rate their pain. Electroacupuncture was performed at acupoints DI 4 and DI 10 contralaterally with 20 min of stimulation prior to and throughout the SETT. Dependent measures were “time”, “average rating over time”, “pain tolerance index” (time/rating). Results Mean pain ratings were significantly reduced for electroacupuncture and the opiate condition compared to non-treatment control, the placebo pill and Ibuprofen, while pain tolerance was increased. There was a tendency for subjects in the opiate and acupuncture condition to tolerate the SETT for a longer period of time. However, the effect was blurred due to a strong ceiling effect (time limit of 30 min). Discussion Electroacupuncture was shown to be as effective as a single dose of an orally administered opiate in reducing experimental tourniquet pain. There was no effect of the placebo pill or Ibuprofen. Therefore, electroacupuncture is as much a placebo as the opiate Tramadol.