Is sham laser a valid control for acupuncture trials?

Abstract

Methodological problems of acupuncture trials focus on adequate placebo controls. In this trial we evaluated the use of sham laser acupuncture as a control procedure. Thirty-four healthy volunteers received verum laser (invisible infrared laser emission and red light, 45 s and 1 J per point) and sham laser (red light) treatment at three acupuncture points (LI4, LU7 and LR3) in a randomized, double-blinded, cross-over design. The main outcome measure was the ratio of correct to incorrect ratings of treatment immediately after each session. The secondary outcome measure was the occurrence of deqi-like sensations at the acupuncture points and their intensity on a 10-fold visual analog scale (VAS; 10 being the strongest sensible sensation). We pooled the results of three former trials to evaluate the credibility of sham laser acupuncture when compared to needle acupuncture. Fifteen out of 34 (44%) healthy volunteers (age: 28 ± 10.7 years) identified the used laser device after the first session and 14 (41%) after the second session. Hence, both treatments were undistinguishable (P = .26). Deqi-like sensations occurred in 46% of active laser (2.34 VAS) and in 49.0% of sham laser beams (2.49 VAS). The credibility of sham laser was not different from needle acupuncture. Sham laser acupuncture can serve as a valid placebo control in laser acupuncture studies. Due to similar credibility and the lack of sensory input on the peripheral nervous system, sham laser acupuncture can also serve as a sham control for acupuncture trials, in order to evaluate needling effects per se.

Figure 1

Enrolment in the study.

Figure 2

Ratio of correctly indentified devices (in percent) in the laser (black bars) and sham laser (grey) treatment group. Devices could be considered active, inactive or indistinguishable.

Figure 3

Indicating the standardized mean difference in credibility according to Vincent which is comprised of four items: (i) (Alleviation) How confident do you feel that this treatment can alleviate your complaint? (ii) (Recommendation) How confident would you be in recommending this treatment to a friend who suffered from similar complaints? (iii) (Logic) How logical does this treatment seem to you? (iv) (Other) How successful do you think this treatment would be in alleviating other complaints? SD, standard deviation; CI, 95% confidence interval.

Figure 4

Specific and non-specific effects of needle acupuncture, laser- and sham laser acupuncture.