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Effect of Acupuncture Upon Experimentally Induced Ischemic Pain: A Sham-Controlled Single-Blind Study

Barlas, Panos D.Phil*; Lowe, Andrea S. D.Phil; Walsh, Deirdre M. D.Phil; Baxter, G. David D.Phil; Allen, Jim M. Ph.D

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Objective: To investigate the hypoalgesic effect of true and sham acupuncture upon experimentally induced ischemic pain.

Design: Human volunteers (n = 60) were required to attend two sessions for pain induction using a submaximal effort tourniquet technique; on the first occasion, baseline pain scores were recorded and on the second, 48 hours later, subjects were randomly allocated to one of five groups: Control, Treatment Groups 1 or 2, or Placebo Groups 1 or 2.

Subjects: Healthy human volunteers.

Intervention: In all the Treatment and Placebo Groups, subjects received some form of needle acupuncture 15 minutes before, and 5 minutes during, the pain induction procedure on the second day. Treatment Group 1 received acupuncture on acupuncture points situated distal to the tourniquet, whereas Treatment Group 2 received acupuncture on acupuncture points situated proximal to the tourniquet. In Placebo Groups 1 and 2, subjects received 'sham' acupuncture either on nonacupuncture points (Placebo Group 1) or on acupuncture points (Placebo Group 2) using (standardized) minimal levels of stimulation. A licensed acupuncturist who was not involved in data collection and analyses carried out all treatments.

Outcome Measures: Pain was assessed using a computerized visual analog scale (VAS) and a McGill Pain Questionnaire (MPQ).

Results: Analysis of VAS scores using ANOVA revealed no significant differences between groups (e.g., VAS sum of differences data (mean ± SEM): Treatment Group 1: 90±47, Treatment Group 2: 187±56, Placebo Group 1: 152±40, Placebo Group 2: 121±42, Controls: 46±24, p>0.05). Analysis of MPQ percentage difference scores using one-way ANOVA revealed some isolated effects in the subjective descriptors and the Pain Rating Index, both for Treatment Group 2 and Placebo Group 2, proving them superior to any of the other groups.

Conclusion: The results of the study provide no convincing evidence for a superior hypoalgesic effect of acupuncture compared with "sham" procedures on this model of experimental pain.

*School of Health and Social Sciences, Coventry University, Coventry, United Kingdom, and Keele University, England; †Rehabilitation Sciences Research Group, School of Health Sciences, ‡Magee College, University of Ulster, Jordanstown, United Kingdom

Received October 12, 1999; revised March 24, 2000; accepted April 10, 2000.

Address correspondence to Dr. Panos Barlas, School of Health and Social Sciences, Coventry University, Priory Street, Coventry CV1 5FB, United Kingdom; e-mail: p.barlas@coventry.ac.uk

© 2000 Lippincott Williams & Wilkins, Inc.