Perception of bodily sensation as a predictor of treatment response to acupuncture for postoperative nausea and vomiting prophylaxis

A Review of Acupuncture Clinical Trials Indexed during 2005

Background

Clinical trials in acupuncture are published in a variety of journals, and it is useful to summarise them in one place.

Methods

We conducted a search of PubMed and Embase for clinical trials of acupuncture with date of entry 2005, and selected randomised controlled trials with clinical outcomes for review. Where possible, the original report was read for full details.

Results

Thirty-eight RCTs were found from databases, and one more during the process of the study. Ten of the trials included about 100 patients or more. Five showed acupuncture to be superior to usual care in back pain, knee pain and headache. Acupuncture was superior to placebo for chronic knee pain, but not for fibromyalgia, or post-stroke rehabilitation. Acupuncture was not as good as conventional analgesia for oocyte collection.

Conclusion

The role of acupuncture is becoming more precisely established in treatment of chronic knee pain, back pain and headache. Acupuncture for chronic back pain is more cost-effective than many other medical interventions.

Phantom Acupuncture Induces Placebo Credibility and Vicarious Sensations: A Parallel fMRI Study of Low Back Pain Patients

Although acupuncture is an effective therapeutic intervention for pain reduction, the exact difference between real and sham acupuncture has not been clearly understood because a somatosensory tactile component is commonly included in the existing sham acupuncture protocols. In an event-related fMRI experiment, we implemented a novel form of sham acupuncture, phantom acupuncture, that reproduces the acupuncture needling procedure without somatosensory tactile stimulation while maintaining the credibility of the acupuncture treatment context. Fifty-six non-specific low back pain patients received either real (REAL) or phantom (PHNT) acupuncture stimulation in a parallel group study. The REAL group exhibited greater activation in the posterior insula and anterior cingulate cortex, reflecting the needling-specific components of acupuncture. We demonstrated that PHNT could be delivered credibly. Interestingly, the PHNT-credible group exhibited bilateral activation in SI/SII and also reported vicarious acupuncture sensations without needling stimulation. The PHNT group showed greater activation in the bilateral dorsolateral/ventrolateral prefrontal cortex (dlPFC/vlPFC). Moreover, the PHNT group exhibited significant pain reduction, with a significant correlation between the subjective fMRI signal in the right dlPFC/vlPFC and a score assessing belief in acupuncture effectiveness. These results support an expectation-related placebo analgesic effect on subjective pain intensity ratings, possibly mediated by right prefrontal cortex activity.

Electroacupuncture combined with mosapride alleviates symptoms in diabetic patients with gastroparesis

The present study compared the clinical effectiveness of electroacupuncture (EA), monotherapy and combination therapy involving the administration of EA and mosapride in diabetic patients with severe or mild symptoms suggestive of gastroparesis. A total of 56 patients with type 2 diabetes who had symptoms suggestive of gastroparesis for >3 months were divided into two groups according to the Gastroparesis Cardinal Symptom Index (GCSI) score, including 33 in the mild group (GCSI score <3.5) and 23 in the severe group (GCSI score ≥3.5). Initially, all patients received EA monotherapy for 14 days. An effective response was defined as a reduction of the overall baseline GCSI score by >25% after treatment. The non-responding patients then received a combination treatment with EA and mosapride. Gastric emptying was assessed by the ¹³C-octanoic acid breath test at the beginning and end of each treatment session. Two patients in the severe group dropped out of the study during the initial treatment session. The results revealed that 34 early-responding patients (30 from the mild group and 4 from the severe group) treated with EA monotherapy, and 20 non-early-responding patients receiving combination therapy with EA and mosapride showed clinically significant improvements. Analysis of data from the mild subgroup demonstrated that EA treatment specifically improved symptoms of nausea, vomiting, stomach fullness, excessive fullness and bloating. There was no statistically significant difference in the gastric half-emptying time among patients prior to and after EA monotherapy. These preliminary results suggested that EA may be an option for improving mild symptoms in patients with diabetic gastroparesis, whereas combination therapy involving EA and pharmaceutics is required in patients with severe symptoms.

Effect of acupuncture and its influence on cerebral activity in functional dyspepsia patients: study protocol for a randomized controlled trial

BACKGROUND

Functional dyspepsia (FD) is a prevalent gastric disorder that is difficult to manage due to lack of satisfactory treatments. Acupuncture has been studied with regard to the rising need for treating FD, but the mechanism verifying its efficacy has not yet been fully revealed. The aim of this study is to explore the efficacy and mechanism of acupuncture for FD compared with a sham group.

METHODS/DESIGN

We describe a proposal for a randomized, assessor-blind, sham-controlled trial with 70 eligible participants who will be randomly allocated either into an acupuncture or a sham group. Participants in the acupuncture group will receive 10 sessions of real acupuncture treatment and those in the sham group will be treated with identical sessions using a Streitberger needle. Functional magnetic resonance imaging (fMRI) and metabolomics studies will be implemented before and after 4 weeks of treatment to investigate the mechanism of acupuncture. The primary outcome is a proportion of responders with adequate symptom relief and the secondary outcomes include the Nepean Dyspepsia Index - Korean version, Functional Dyspepsia-Related Quality of Life questionnaire, Ways of Coping Questionnaire, Coping Strategies Questionnaire, perception of bodily sensation questionnaire, State-Trait Anxiety Inventory, and the Center for Epidemiological Studies - Depression Scale. The outcomes will be evaluated before and after the treatment.

DISCUSSION

This is the first large-scale trial evaluating the efficacy and mechanism of acupuncture with fMRI and metabolomic methods. We will compare real acupuncture with the Streitberger sham needle to verify the specific effect of acupuncture. The results of this trial are expected to be relevant evidences affecting policy and decision-makers associated with routine healthcare.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02358486 . Date of Registration: 21 January 2015.

Stimulation of the wrist acupuncture point PC6 for preventing postoperative nausea and vomiting

BACKGROUND

Postoperative nausea and vomiting (PONV) are common complications following surgery and anaesthesia. Antiemetic drugs are only partially effective in preventing PONV. An alternative approach is to stimulate the PC6 acupoint on the wrist. This is an update of a Cochrane review first published in 2004, updated in 2009 and now in 2015.

OBJECTIVES

To determine the effectiveness and safety of PC6 acupoint stimulation with or without antiemetic drug versus sham or antiemetic drug for the prevention of PONV in people undergoing surgery.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library, Issue 12, 2014), MEDLINE (January 2008 to December 2014), EMBASE (January 2008 to December 2014), ISI Web of Science (January 2008 to December 2014), World Health Organization Clinical Trials Registry, ClinicalTrials.gov, and reference lists of articles to identify additional studies. We applied no language restrictions.

SELECTION CRITERIA

All randomized trials of techniques that stimulated the PC6 acupoint compared with sham treatment or drug therapy, or combined PC6 acupoint and drug therapy compared to drug therapy, for the prevention of PONV. Interventions used in these trials included acupuncture, electro-acupuncture, transcutaneous electrical acupoint stimulation, transcutaneous nerve stimulation, laser stimulation, capsicum plaster, acu-stimulation device, and acupressure in people undergoing surgery. Primary outcomes were the incidences of nausea and vomiting after surgery. Secondary outcomes were the need for rescue antiemetic therapy and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data and assessed the risk of bias domains for each trial. We used a random-effects model and reported risk ratio (RR) with associated 95% confidence interval (95% CI). We used trial sequential analyses to help provide information on when we had reached firm evidence in cumulative meta-analyses of the primary outcomes, based on a 30% risk ratio reduction in PONV.

MAIN RESULTS

We included 59 trials involving 7667 participants. We rated two trials at low risk of bias in all domains (selection, attrition, reporting, blinding and other). We rated 25 trials at high risk in one or more risk-of-bias domains. Compared with sham treatment, PC6 acupoint stimulation significantly reduced the incidence of nausea (RR 0.68, 95% CI 0.60 to 0.77; 40 trials, 4742 participants), vomiting (RR 0.60, 95% CI 0.51 to 0.71; 45 trials, 5147 participants) and the need for rescue antiemetics (RR 0.64, 95% CI 0.55 to 0.73; 39 trials, 4622 participants). As heterogeneity among trials was substantial and there were study limitations, we rated the quality of evidence as low. Using trial sequential analysis, the required information size and boundary for benefit were reached for both primary outcomes.PC6 acupoint stimulation was compared with six different types of antiemetic drugs (metoclopramide, cyclizine, prochlorperazine, droperidol. ondansetron and dexamethasone). There was no difference between PC6 acupoint stimulation and antiemetic drugs in the incidence of nausea (RR 0.91, 95% CI 0.75 to 1.10; 14 trials, 1332 participants), vomiting (RR 0.93, 95% CI 0.74 to 1.17; 19 trials, 1708 participants), or the need for rescue antiemetics (RR 0.87, 95% CI 0.65 to 1.16; 9 trials, 895 participants). We rated the quality of evidence as moderate, due to the study limitations. Using trial sequential analyses, the futility boundary was crossed before the required information size was surpassed for both primary outcomes.Compared to antiemetic drugs, the combination of PC6 acupoint stimulation and antiemetic therapy reduced the incidence of vomiting (RR 0.56, 95% CI 0.35 to 0.91; 9 trials, 687 participants) but not nausea (RR 0.79, 95% CI 0.55 to 1.13; 8 trials, 642 participants). We rated the quality of evidence as very low, due to substantial heterogeneity among trials, study limitations and imprecision. Using trial sequential analysis, none of the boundaries for benefit, harm or futility were crossed for PONV. The need for rescue antiemetic was lower in the combination PC6 acupoint stimulation and antiemetic group than the antiemetic group (RR 0.61, 95% CI 0.44 to 0.86; 5 trials, 419 participants).The side effects associated with PC6 acupoint stimulation were minor, transient and self-limiting (e.g. skin irritation, blistering, redness and pain) in 14 trials. Publication bias was not apparent in the contour-enhanced funnel plots.

AUTHORS' CONCLUSIONS

There is low-quality evidence supporting the use of PC6 acupoint stimulation over sham. Compared to the last update in 2009, no further sham comparison trials are needed. We found that there is moderate-quality evidence showing no difference between PC6 acupoint stimulation and antiemetic drugs to prevent PONV. Further PC6 acupoint stimulation versus antiemetic trials are futile in showing a significant difference, which is a new finding in this update. There is inconclusive evidence supporting the use of a combined strategy of PC6 acupoint stimulation and antiemetic drug over drug prophylaxis, and further high-quality trials are needed.

Pain and sensory detection threshold response to acupuncture is modulated by coping strategy and acupuncture sensation

BACKGROUND

Acupuncture has been shown to reduce pain, and acupuncture-induced sensation may be important for this analgesia. In addition, cognitive coping strategies can influence sensory perception. However, the role of coping strategy on acupuncture modulation of pain and sensory thresholds, and the association between acupuncture sensation and these modulatory effects, is currently unknown.

METHODS

Electroacupuncture (EA) was applied at acupoints ST36 and GB39 of 61 healthy adults. Different coping conditions were experimentally designed to form an active coping strategy group (AC group), who thought they could control EA stimulation intensity, and a passive coping strategy group (PC group), who did not think they had such control. Importantly, neither group was actually able to control EA stimulus intensity. Quantitative sensory testing was performed before and after EA, and consisted of vibration (VDT), mechanical (MDT), warm (WDT), and cold (CDT) detection thresholds, and pressure (PPT), mechanical (MPT), heat (HPT) and cold (CPT) pain thresholds. Autonomic measures (e.g. skin conductance response, SCR) were also acquired to quantify physiological response to EA under different coping conditions. Subjects also reported the intensity of any acupuncture-induced sensations.

RESULTS

Coping strategy was induced with successful blinding in 58% of AC subjects. Compared to PC, AC showed greater SCR to EA. Under AC, EA reduced PPT and CPT. In the AC group, improved pain and sensory thresholds were correlated with acupuncture sensation (VDTchange vs. MI: r=0.58, CDTchange vs. tingling: r=0.53, CPTchange vs. tingling; r=0.55, CPTchange vs. dull; r=0.55). However, in the PC group, improved sensory thresholds were negatively correlated with acupuncture sensation (CDTchange vs. intensity sensitization: r=-0.52, WDTchange vs. fullness: r=-0.57).

CONCLUSIONS

Our novel approach was able to successfully induce AC and PC strategies to EA stimulation. The interaction between psychological coping strategy and acupuncture sensation intensity can differentially modulate pain and sensory detection threshold response to EA. In a clinical context, our findings suggest that instructions given to the patient can significantly affect therapeutic outcomes and the relationship between acupuncture intensity and clinical response. Specifically, acupuncture analgesia can be enhanced by matching physical stimulation intensity with psychological coping strategy to acupuncture contexts.

TRIAL REGISTRATION

KCT0000905.

Heat stimulation on the skin for medical treatment: can it be controlled?

OBJECTIVES

It has become increasingly important for evidence-based medicine to have a proper control for randomized-controlled trials. However, appropriately controlling manual therapies such as moxibustion has proved challenging. Our team designed a novel device based on sensory illusion, and tested its feasibility.

DESIGN AND RESULTS

A sham moxibustion device was constructed to allow participants to feel moxibustion treatment without actually stimulating the corresponding acupoint. The device consisted of two pieces of aluminum, each shaped like a horseshoe, so that the center of the device would not touch the skin. Participants perceived two heat stimuli as one when the distances of two heat sources were within 15 mm on the forearm. The thermal stimulation of the sham device was adjusted to the lowest possible temperature, but enough to elicit a heat sensation (39°C), while that of verum was set at around 44°C. The subject blinding, tested in 30 healthy volunteers, was successful. With the exception of 1 subject, subjects in the sham group described the sensation as a warm solid circle, unable to differentiate between two-pieced sham moxibustion and verum moxibustion.

CONCLUSIONS

This preliminary study indicates that this device may serve as an appropriate control for clinical studies of moxibustion, but more research is clearly needed. A validated sham moxibustion device based on sensory illusion may contribute in expanding knowledge of somatosensory studies.

Body awareness: construct and self-report measures

Objectives

Heightened body awareness can be adaptive and maladaptive. Improving body awareness has been suggested as an approach for treating patients with conditions such as chronic pain, obesity and post-traumatic stress disorder. We assessed the psychometric quality of selected self-report measures and examined their items for underlying definitions of the construct.

Data sources

PubMed, PsychINFO, HaPI, Embase, Digital Dissertations Database.

Review methods

Abstracts were screened; potentially relevant instruments were obtained and systematically reviewed. Instruments were excluded if they exclusively measured anxiety, covered emotions without related physical sensations, used observer ratings only, or were unobtainable. We restricted our study to the proprioceptive and interoceptive channels of body awareness. The psychometric properties of each scale were rated using a structured evaluation according to the method of McDowell. Following a working definition of the multi-dimensional construct, an inter-disciplinary team systematically examined the items of existing body awareness instruments, identified the dimensions queried and used an iterative qualitative process to refine the dimensions of the construct.

Results

From 1,825 abstracts, 39 instruments were screened. 12 were included for psychometric evaluation. Only two were rated as high standard for reliability, four for validity. Four domains of body awareness with 11 sub-domains emerged. Neither a single nor a compilation of several instruments covered all dimensions. Key domains that might potentially differentiate adaptive and maladaptive aspects of body awareness were missing in the reviewed instruments.

Conclusion

Existing self-report instruments do not address important domains of the construct of body awareness, are unable to discern between adaptive and maladaptive aspects of body awareness, or exhibit other psychometric limitations. Restricting the construct to its proprio- and interoceptive channels, we explore the current understanding of the multi-dimensional construct and suggest next steps for further research.

Stimulation of the wrist acupuncture point P6 for preventing postoperative nausea and vomiting

BACKGROUND

Postoperative nausea and vomiting (PONV) are common complications following surgery and anaesthesia. Drugs to prevent PONV are only partially effective. An alternative approach is to stimulate the P6 acupoint on the wrist. This is an update of a Cochrane review first published in 2004.

OBJECTIVES

To determine the efficacy and safety of P6 acupoint stimulation in preventing PONV.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library, Issue 3, 2008), MEDLINE (January 1966 to September 2008), EMBASE (January 1988 to September 2008), ISI Web of Science (January 1965 to September 2008), the National Library of Medicine publication list of acupuncture studies, and reference lists of articles.

SELECTION CRITERIA

All randomized trials of techniques that stimulated the P6 acupoint compared with sham treatment or drug therapy for the prevention of PONV. Interventions used in these trials included acupuncture, electro-acupuncture, transcutaneous nerve stimulation, laser stimulation, capsicum plaster, an acu-stimulation device, and acupressure in patients undergoing surgery. Primary outcomes were the risks of nausea and vomiting. Secondary outcomes were the need for rescue antiemetic therapy and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted the data. We collected adverse effect information from the trials. We used a random-effects model and reported relative risk (RR) with associated 95% confidence intervals (95% CI).

MAIN RESULTS

We included 40 trials involving 4858 participants; four trials reported adequate allocation concealment. Twelve trials did not report all outcomes. Compared with sham treatment P6 acupoint stimulation significantly reduced: nausea (RR 0.71, 95% CI 0.61 to 0.83); vomiting (RR 0.70, 95% CI 0.59 to 0.83), and the need for rescue antiemetics (RR 0.69, 95% CI 0.57 to 0.83). Heterogeneity among trials was moderate. There was no clear difference in the effectiveness of P6 acupoint stimulation for adults and children; or for invasive and noninvasive acupoint stimulation. There was no evidence of difference between P6 acupoint stimulation and antiemetic drugs in the risk of nausea (RR 0.82, 95% CI 0.60 to 1.13), vomiting (RR 1.01, 95% CI 0.77 to 1.31), or the need for rescue antiemetics (RR 0.82, 95% CI 0.59 to 1.13). The side effects associated with P6 acupoint stimulation were minor. There was no evidence of publication bias from contour-enhanced funnel plots.

AUTHORS' CONCLUSIONS

P6 acupoint stimulation prevented PONV. There was no reliable evidence for differences in risks of postoperative nausea or vomiting after P6 acupoint stimulation compared to antiemetic drugs.

A review of psychosocial predictors of treatment outcomes: what factors might determine the clinical success of acupuncture for pain?

This narrative review examines the psychosocial factors that might predict clinical outcomes in acupuncture for pain. Given existing evidence concerning the clinical effectiveness and safety of acupuncture in painful conditions, it is important to consider how clinicians might further improve their effectiveness. The relevant theoretical frameworks focus primarily on the patient, suggesting that their background characteristics and their beliefs about pain and acupuncture should be considered as potential predictors of outcome. The self-regulation model within health psychology helps us understand how people manage their health and integrate interventions like acupuncture into the management of their illness. This model also implies that the therapeutic relationship, in particular patients' perceptions of that relationship, is likely to be related to outcome. The empirical literature in this area is sparse. However, the findings to date do suggest that a number of psychosocial factors, in particular patients' beliefs about acupuncture, are significant predictors of treatment outcomes from acupuncture for pain. Factors related to the therapeutic relationship are also likely to be important in facilitating good clinical outcomes. We discuss the limitations of the existing studies and make recommendations for future research in this area. If we can better understand the psychosocial factors involved in acupuncture, then we should be able to enhance acupuncture treatments and improve outcomes for patients. These observations will, therefore, have potential to allow us to develop techniques that may improve clinical outcomes in the treatment of pain.

Acupuncture for nausea and vomiting: An update of clinical and experimental studies

The objective of this overview is to summarize existing knowledge about the effects of acupuncture-point stimulation on nausea and vomiting. Systematic reviews on postoperative nausea and vomiting, chemotherapy-induced nausea and vomiting, and pregnancy-related nausea and vomiting exist. Several randomised trials, but no reviews, exist for motion sickness. For postoperative nausea and vomiting, results from 26 trials showed acupuncture-point stimulation was effective for both nausea and vomiting. For chemotherapy-induced nausea and vomiting, results of 11 trials differed according to modality with acupressure appearing effective for first-day nausea, electroacupuncture appearing effective for first-day vomiting, and noninvasive electrostimulation appearing no more effective than placebo for any outcome. For pregnancy-related nausea and vomiting, results were mixed. Experimental studies showed effects of P6-stimulation on gastric myoelectrical activity, vagal modulation and cerebellar vestibular activities in functional magnetic resonance imaging. There is good clinical evidence from more than 40 randomised controlled trials that acupuncture has some effect in preventing or attenuating nausea and vomiting. A growing number of experimental studies suggest mechanisms of action.

How might acupuncture work? A systematic review of physiologic rationales from clinical trials

BACKGROUND

Scientific interest in acupuncture has led numerous investigators to conduct clinical trials to test the efficacy of acupuncture for various conditions, but the mechanisms underlying acupuncture are poorly understood.

METHODS

The author conducted a PubMed search to obtain a fair sample of acupuncture clinical trials published in English in 2005. Each article was reviewed for a physiologic rationale, as well as study objectives and outcomes, experimental and control interventions, country of origin, funding sources and journal type.

RESULTS

Seventy-nine acupuncture clinical trials were identified. Twenty-six studies (33%) offered no physiologic rationale. Fifty-three studies (67%) posited a physiologic basis for acupuncture: 33 (62% of 53) proposed neurochemical mechanisms, 2 (4%) segmental nervous system effects, 6 (11%) autonomic nervous system regulation, 3 (6%) local effects, 5 (9%) effects on brain function and 5 (9%) other effects. No rationale was proposed for stroke; otherwise having a rationale was not associated with objective, positive or negative findings, means of intervention, country of origin, funding source or journal type. The dominant explanation for how acupuncture might work involves neurochemical responses and is not reported to be dependent on treatment objective, specific points, means or method of stimulation.

CONCLUSION

Many acupuncture trials fail to offer a meaningful rationale, but proposing a rationale can help investigators to develop and test a causal hypothesis, choose an appropriate control and rule out placebo effects. Acupuncture may stimulate self-regulatory processes independent of the treatment objective, points, means or methods used; this would account for acupuncture's reported benefits in so many disparate pathologic conditions.

Metaanalyses of Acustimulations: Effects on Nausea and Vomiting in Postoperative Adult Patients

OBJECTIVE

Using metaanalysis to examine the effects of acustimulations on nausea and vomiting symptoms (NVS) in postoperative adult populations.

METHODS

Metaanalyses of effects of various acupoints stimulations (AS) (including acupuncture, acupressure, and electrical stimulation) on NVS in postoperative adult populations were performed. Thirty-three quality randomized controlled trials (RCT) published over the past three decades were identified by evaluating the quality of randomization and treatment methods, and results were pooled using a fixed effects model.

RESULTS

Twenty-four trials were pooled for nausea, 29 trials for vomiting, and 19 trials for rescue antiemetics, with AS compared with placebo or controls. Two additional trials did not have control groups but compared AS to medication groups. Compared with the controls, AS (all modalities) reduced nausea (relative risk [RR] = 0.60, 95% confidence interval [CI]: 0.54-0.67, P < .0001), vomiting (RR = 0.51, 95% CI: 0.45-0.57, P < .0001), and use of rescue antiemetics (RR = 0.63, 95% CI: 0.54-0.74, P < 0001). All AS modalities were effective in reducing NVS. Korean hand acupressure stimulations (two trials) had the best impact on reducing vomiting. There were no significant differences on pooled RRs for nausea (five trials) and vomiting (eight trials) between medication and AS groups, but medication groups had increased use of rescue antiemetics (two trials, RR = 2.27, 95% CI: 1.48-3.49, P = .0002). There was a placebo effect when compared with controls in reducing nausea (four trials, RR = 0.67, 95% CI: 0.50-0.90, P = .0069) and vomiting (three trials, RR = 0.39, 95% CI: 0.19-0.80, P = .0106).

CONCLUSIONS

This metaanalysis demonstrated that AS is just as effective as medications in reducing NVS and that acupressure is just as effective as acupuncture or electrical stimulation in reducing NVS for postoperative adult populations.

Effects of intensity of electroacupuncture upon experimental pain in healthy human volunteers: a randomized, double-blind, placebo-controlled study

Electroacupuncture is commonly used for pain relief. Despite an extensive evidence-base guiding the selection of stimulation parameters, little methodologically robust research exists regarding the level of intensity required to provide effective doses. This study investigated the hypoalgesic effects of two stimulation intensities compared to placebo on pressure pain thresholds (PPTs) in pain-free humans. Forty-eight acupuncture-naïve volunteers (mean age 23), stratified by gender, were screened for relevant contraindications and randomly allocated to four groups: control, placebo, high-intensity ("to tolerance but sub-noxious") or low-intensity ("strong but comfortable"). True or placebo electroacupuncture, using the Streitberger placebo needle, was administered to acupoints on dominant forearm (LI10, TH5) and ipsilateral leg (GB34, ST38). True needles (30 mm long, 0.3 mm diameter) were inserted 20-25 mm and "de-qi" was elicited from active groups, prior to administering 30 min of 4 Hz, 200 micros electroacupuncture. No electrical stimulation was performed on control and placebo groups, and placebo needles were used. After the intervention period, all needles were removed. Volunteers were monitored for 30 further minutes. Two PPT measurements were taken bilaterally from muscle bellies of first dorsal interosseous by an independent rater, at baseline and at six subsequent 10-min intervals. Square-root transformed data were analysed using repeated-measures ANOVA, with baseline data as covariate. The high-intensity group was significantly different from the placebo group for both measurement sites (p=.020, p=.033). The control group displayed stable PPT readings over time. No significant differences were observed between the placebo and control groups. These findings suggest that high-intensity levels may be important in optimal dose selection.