Can individuals identify if needling was performed with an acupuncture needle or a non-penetrating sham needle?

A control treatment in acupuncture research must be credible, regardless if the needling is performed by one or by several therapists. OBJECTIVE: To investigate if individuals could identify whether needling had been given with an acupuncture needle or a sham needle and if the therapist influenced this ability. DESIGN: Eighty individuals were randomized to one single needling given by one of four physiotherapists using either an invasive needle or a non-penetrating telescopic sham needle. RESULTS: An equal proportion of individuals, 27 (68%), in the acupuncture group and the sham group answered incorrectly or was not sure at all regarding needling type but the proportion varied between the therapists from 55 to 80% (ns). Bang\'s blinding index was 0.20 (95% CI 0.03-0.36) in the acupuncture group and 0.10 (95% CI 0.09-0.29) in the sham group (interpretation: 20 and 10% identified needling type beyond statistical chance). Acupuncture was on a four-grade scale rated as median \"mildly painful\" and sham as \"not painful\" (ns). Pain ratings varied from median \"not\" to \"mildly painful\" in the therapists (p = 0.01). CONCLUSIONS: Two thirds of individuals needled by acupuncture as well as sham could not identify needling type and only 10-20% of the individuals were unblinded beyond chance. The therapists, not the needling type, influenced how painful the needling was perceived. IMPLICATIONS: To achieve blinding success in acupuncture efficacy studies using the sham needle, the needling procedure must be strictly standardized in order to minimize differences between the therapists.