Evidence for physiotherapy practice: A survey of the Physiotherapy Evidence Database (PEDro)

A problem acupuncture research has to face is the concept of a control group. If, in control groups, non-acupoint needling is done, physiological acupuncture effects are implied. Therefore the effects shown in this group are often close to those shown in the acupuncture group. In other trials, control groups have received obviously different treatments, such as transcutaneous electrical nervous stimulation or TENS-laser treatment; it is not clear if the effects of acupuncture are due only to the psychological effects of the treatment. We developed a placebo acupuncture needle, with which it should be possible to simulate an acupuncture procedure without penetrating the skin. In a cross-over experiment with 60 volunteers we tested whether needling with the placebo needle feels any different from real acupuncture. Of 60 volunteers, 54 felt a penetration with acupuncture (mean visual analogue scale [VAS] 13.4; SD 10.58) and 47 felt it with placebo (VAS 8.86; SD 10.55), 34 felt a dull pain sensation (DEQI) with acupuncture and 13 with placebo. None of the volunteers suspected that the needle may not have penetrated the skin. The placebo needle is sufficiently credible to be used in investigations of the effects of acupuncture.

Researchers have a number of different options for their choice of control or comparison intervention in randomized trials. We surveyed the methodological literature looking for reasons why a researcher might choose to administer a placebo (i.e., a mimic intervention) to control subjects. Two implicit assumptions were that the issue of placebo is pertinent only to drug trials and that the nonplacebo effect of a treatment is the "real" or "true" effect. Explicit reasons given in the literature for the use of placebos were facilitating blinding and controlling for the placebo effect. The importance of the latter was often inadequately argued. Reasons to avoid placebos in controlled trials, other than ethics and feasibility, are that placebos do not inform real decisions, and may interfere with accurate estimation of effect size and with nonspecific aspects of treatment. Placebo-controlled trials have high internal validity but may be difficult to apply to clinical practice; the situation is reversed for trials without placebo control.