In a groundbreaking study conducted at the University of Alberta Hospital, researchers have discovered a method to achieve true blinding for subjects undergoing spinal manipulative therapy (SMT). In 2009, led by Gregory N Kawchuk and his team, the study aimed to determine if short-duration anesthesia could effectively mask subjects’ awareness of whether they received SMT or not.

Published in the Archives of physical medicine and rehabilitation, the study enrolled six human subjects experiencing uncomplicated low back pain (LBP). Each participant was administered a combination of propofol and remifentanil intravenously to induce a brief state of unconsciousness. Once unconsciousness was achieved, subjects were randomly assigned to either a control group or an experimental group receiving SMT to the lumbar spine.

The key innovation of this study lies in its methodology. Unlike previous attempts at blinding for SMT, which often relied on sham procedures that could be discerned by participants, this study employed anesthesia to ensure complete unawareness of treatment allocation. Subjects were carefully monitored to ensure safety throughout the procedure.

Before anesthesia and 30 minutes after recovery, each subject was asked to rate their LBP on an 11-point scale by a blinded evaluator. Additionally, the evaluator assessed subjects’ ability to recall specific memories, including treatment events and auditory and visual cues, during the presumed anesthesia period.

Remarkably, subjects in both the experimental and control groups were unable to recall any events during anesthesia, indicating the effectiveness of the blinding technique. Moreover, some subjects who received SMT reported significant reductions in pain compared to control subjects, surpassing the minimally important clinical difference.

Importantly, no adverse events were reported during the study, highlighting the safety of the anesthesia-based blinding approach. The findings of this study pave the way for future placebo-controlled randomized trials to evaluate the efficacy of SMT with unprecedented accuracy.

While further research is warranted to refine this technique and validate its applicability in larger cohorts, this study represents a significant advancement in the quest to objectively assess the effectiveness of spinal manipulative therapy. With the potential to conduct rigorous placebo-controlled trials, clinicians and researchers are poised to gain deeper insights into the role of SMT in managing low back pain.

Reference: Kawchuk, G. N., Haugen, R., & Fritz, J. (2009). A true blind for subjects who receive spinal manipulation therapy. Archives of physical medicine and rehabilitation, 90(2), 366-368.