Original article
The Effect of Real and Sham Acupuncture on Thermal Sensation and Thermal Pain Thresholds

https://doi.org/10.1016/j.apmr.2004.10.037Get rights and content

Abstract

Downs NM, Kirk K, MacSween A. The effect of real and sham acupuncture on thermal sensation and thermal pain thresholds. Arch Phys Med Rehabil 2005;86:1252–7.

Objective

To compare the effect of real and sham acupuncture and a control intervention on thermal sensation and thermal pain thresholds.

Design

Single-blind, randomized controlled, repeated-measures trial.

Setting

Laboratory.

Participants

Eighteen acupuncture naive, healthy subjects with no history of upper-limb pathology or acupuncture contraindications.

Intervention

Subjects were randomly assigned (blind card allocation) to 1 of 6 possible orders of application of the interventions, which consisted of 25 minutes each of control, real, and sham acupuncture.

Main Outcome Measures

Thermal sensation and thermal pain thresholds measured with a thermal sensory analyzer before and after each intervention.

Results

There were increases in cold and hot pain and cold sensation thresholds with real acupuncture. The level of increase did not differ significantly from the changes that occurred with sham acupuncture and control interventions.

Conclusions

Although we observed a trend toward a decreased sensitivity to thermal pain and thermal sensation with real acupuncture, this trend did not differ significantly from the changes with control or sham interventions. Therefore, no support was provided for analgesic or placebo effects of acupuncture. The trend, combined with the relatively low power of the inferential tests applied does, however, suggest that further research is merited.

Section snippets

Design

This study was a single-blind randomized controlled repeated-measures (within-subject) trial. The independent variable was acupuncture (real, sham). The dependent variables were the thermal sensation and thermal pain thresholds.

Participants

A convenience sample of 18 healthy volunteers (12 women, 6 men; mean age ± standard deviation [SD], 29.1±9.2y) was recruited from among students at Queen Margaret University College, who responded to a general notice and word of mouth. All 18 subjects completed the

Results

Mean thermal sensation and thermal pain thresholds are presented in table 2. There were no statistically significant differences (P>.05) between the baseline values of any of the 4 thermal thresholds recorded before application of each of the 3 interventions were applied. Inferential comparisons were therefore made of the levels of change calculated in degrees Celsius. The levels of change in thermal sensation and thermal pain thresholds are presented in table 3 as the mean of the changes

Discussion

Our results show no significant differences in the level of change in thermal sensation and thermal pain thresholds when the 3 interventions were applied. Hence, 2 inferences can be made: first, real acupuncture did not have any significantly greater analgesic effect (as represented by change in thermal sensation and thermal pain thresholds) in comparison with sham and control. Second, because there was no significant difference between sham and control, there was no evidence of a placebo

Conclusions

We found no statistically significant differences between real and sham acupuncture and a control intervention on thermal sensation and thermal pain thresholds in this cohort. Consequently, no support was provided for the analgesic and placebo effects of acupuncture. A trend to a reduction in sensitivity to all thresholds was observed with real acupuncture, but the changes were small relative to the underlying variance. The low power of the inferential tests applied could have resulted from

Acknowledgments

We thank Andrew Grainger, BSc, for technical support and Judith Lane, MSc, MCSP, for statistical advice.

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    Supported by the Arthritis Research Campaign, Chartered Society of Physiotherapy, Hilda Martindale Educational Trust, SmithKlineGlaxo, and the Sir Richard Stapley Educational Trust.

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors(s) or upon any organization with which the author(s) is/are associated.

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