Evaluation of the double-blinding of a novel sham acupuncture method in a clinical trial

Abstract

Objective: To evaluate the double-blinding and clinical performance of a novel placebo acupuncture device in patients with craniomandibular pain of muscular/myofascial origin.

Methods: A randomized, controlled, triple-blind, crossover clinical trial was conducted with 46 patients and 2 acupuncturists. Ten acupuncture sessions were performed at bilateral points (ST6, ST7, SI18, and LI4) using externally identical real and placebo needles. Clinical accuracy (perception of a real needle) and confidence were analyzed in patients. Accuracy, confidence, and the presence of device recognition factors were assessed by acupuncturists. Blinding was determined using the Bang Index (BBI).

Results: Patients showed homogeneous perception between both groups (p=0.069), incorrectly assigning the real needle condition to the placebo in 74% of cases. The Bang Index in the real arm was 0.89 (expected unblinding toward the active treatment), while in the placebo arm it was -0.53, confirming an optimism bias, incorrectly attributing the placebo to the active needle. The overall accuracy of the acupuncturists was close to chance (51.1% overall, p=0.922); although the confidence analysis showed higher confidence when correctly identifying the real needle, when the reported assistance situations were removed and only clean cases were evaluated, the acupuncturist's confidence decreased without showing differences between groups, thus validating the operator's blinding.

Conclusions: The study successfully validated the double-blinding of the new device. The negative Bang Index in the control group confirms the credibility of the design, validating it as a reliable control for future trials in the medical and dental fields.