Wednesday, May 8, 2013

Ear Acupressure for Chronic Back Pain?

Ear AcupressureAuricular point acupressure (APA) is a CAM (complementary and alternative medicine) therapy related to ear acupuncture. Instead of needles, APA uses small seeds or pellets taped to the ear at specific places to stimulate effects elsewhere in the body for treating illness and pain. A small study found that APA was beneficial in relieving chronic low-back pain; however, whether or not this effect was genuine and either APA or ear acupuncture itself are valid therapies for pain conditions are debatable from science-based medicine perspectives.

This study of APA was from an American research team led by Chao Hsing Yeh at the University of Pittsburgh School of Nursing [Yeh et al. 2013]. According to background information in the study report published in Evidence-Based Complementary and Alternative Medicine, customary acupuncture has shown some promising effects for low-back pain, but it is limited by (1) a lack of compelling evidence in high-quality clinical trials, (2) the need for patients to visit an acupuncturist frequently, and (3) associated costs that are often not covered by insurance. Therefore, the researchers believe that APA may offer an attractive solution for treating chronic lower-back pain.

Yeh and colleagues note that APA is a form of auricular therapy, or auriculotherapy, inspired by Traditional Chinese Medicine (TCM) that has used acupoints on specific areas of the inner and outer ear. TCM has incorporated ear acupuncture for 2000 years, claiming that all meridians have reference points on the ear that can be stimulated to regulate internal energy called “Qi.” In 1950, the French neurosurgeon Paul Nogier proposed that points in the ear — which map every part, organ, and system of the body — roughly resemble an inverted fetus within the womb (figure above right). Current auriculotherapy practices and understandings of how the anatomical body is projected onto auricular acupoints now follow Nogier’s theories.

Unlike usual ear acupuncture that most often uses needles, APA uses small objects (eg, botanical plant seeds or metal pellets approximately 2mm in size) applied to a patient’s ear acupoints with small pieces of waterproof tape. Once attached by a trained acupuncturist, patients can self-manage the therapy at home by applying pressure daily to the seeds or pellets.

For their “feasibility study,” Yeh et al. conducted a prospective, randomized controlled trial (RCT) of a 4-week APA regimen for chronic lower-back pain (CLBP). In total, 19 adult patients with CLBP — 15 females, 4 males, average age ≈47 years, range 20-70 years, 89% white — were randomized to either true-APA (Vaccaria seeds taped on ear acupoints designated as suitable for treating CLBP; n=10) or sham-APA (seeds taped on locations different than those deemed appropriate for CLBP; n=9). Patients, but not investigators, were blinded to group allocation.

The primary endpoint was pain assessed on a 10-point numeric rating scale from the Brief Pain Inventory Short Form (BPI). Single scores during the prior 24 hours assessed “worst pain,” “average pain,” and “overall pain intensity” before treatment (baseline), weekly during the 4-week study period, and at 1 month following the end of treatment. Patients also completed a battery of other pain-related assessment instruments during the study.

Results indicated that, compared with sham-APA, participants in the true-APA group at 4-weeks had greater and statistically significant (p<0.05) reductions in “worst pain” (70% vs 26% decrease) and “overall pain” intensity (75% vs 29% decrease). These relationships persisted at the 1-month post-trial followup. Reductions in “average pain” were greater in the true-APA group but were not statistically significant. On measures of general satisfaction with the therapy, neither group expressed that they were “not satisfied,” but those in the true-APA group noted to a greater extent that they were “completely” satisfied.

In other assessments, true-APA appeared to produce more favorable outcomes on most measures than sham-APA, but differences between groups were not statistically significant. These measures included: Roland-Morris Disability Questionnaire, Oswestry Low Back Pain Disability Index, Fear-Avoidance Beliefs questionnaire, the Pain Catastrophizing Scale, and WHO Quality of Life-BREF.

All subjects had been instructed to press the seeds at least 3 times each day for 3 minutes at a time, and at times whenever they experienced pain. Adherence to this regimen was generally good in both groups. Small numbers of participants in both groups reported that their treated ears had more sensitive sensation, soreness, and discomfort, which were deemed tolerable and did not pose safety risks.

Yeh et al. note that this was a first-ever trial to use APA for CLBP under controlled conditions (ie, compared with a sham group), and their results suggest that auricular point acupressure may be a promising treatment in this patient population. APA can be delivered without the use of needles, offering a less invasive alternative to acupuncture, and can be self-administered by patients at home between visits. However, from evidentiary perspectives there are many unanswered questions about both APA and traditional ear acupuncture.

COMMENTARY: Given the preliminary findings in pain reduction, high adherence, and overall safety, APA would seem to have potential as an adjunct therapy — which can be self-administered and is less invasive than customary acupuncture — for CLBP that may help to reduce the necessity for continuous and/or high-dose pharmacotherapy. However, the number of subjects in the study by Yeh and colleagues was so small — more like a series of anecdotes — that the validity of the data and any conclusions need to be cautiously considered.

It is curious that only 2 of 3 measures of pain significantly favored true-APA, and this intervention also failed to demonstrate statistically significant differences on the other 9 measures reported. Part of the reason may be due to evident imbalances between groups at baseline, which is a common flaw when such small groups are randomized and it further questions the validity of the study. For example, Yeh et al. claimed that their trial showed benefits of APA for back-specific disability, but the reported data do not support this contention and there were disparities of up to 135% between groups on these measures at baseline.

Ear Acupoints — “Fairy Tale Science”?

Looking beyond the data of this particular study by Yeh et al., we need to consider whether ear acupoints actually do exist and could possibly have the effects claimed for them. For example, a recent UPDATE article discussed foot reflexology [here], which is somewhat akin to auricular point acupressure in that specific points on the bottom of the foot, believed to correspond with meridians and/or anatomical structures of the body, are stimulated to produce alleged therapeutic effects.

We noted that the biological mechanisms involved in reflexology are undetermined and the prior probability, or scientific plausibility, of any therapeutic effects is questionable. However, what has been called “Fairy Tale Science” in support of reflexology may be using observations based on empirical research data to affirm the validity of concepts that may not truly exist in nature; even though they have been believed to exist by millions of persons for centuries.

A similar question needs to be asked about the existence of acupoints in the ear, and Yeh et al. [2013] concede, “The underlying mechanism of auricular therapy in treating disease/symptoms is still unclear.” In their study, the researchers note that they used an “electronic acupoint finder” to locate points relating to back pain. However, they also state that “there is no empirical evidence regarding the specificity and sensitivity of [this device].” Therefore, they recommend other methods to identify acupoints, including participants’ subjective complaints of symptoms corresponding to auricular points and/or ear skin surface changes.

Some researchers have asserted that many maps exist proposing a correspondence of auricular acupoints to the human body, and all of them “fly in the face of our knowledge of anatomy and physiology” [Ernst 2007]. Others have observed that, while the outer ear is well-innervated, no anatomical pathways exist to directly connect other body structures with the ear [Usichenko et al. 2008]. In one well-designed experiment, using a special probe, researchers found that, although persons with chronic musculoskeletal pain did have tender points on the external ear, those points did not correspond with pain regions or tender zones found in any maps commonly used for auricular acupuncture [Andersson et al. 2007].

Data in the small study by Yeh et al. suggest that they might have distinguished between auricular tender points and those less sensitive, which they thought would be acceptable as sham acupoints. Yet, they also acknowledge that there is little research evidence to suggest optimal criteria for selecting sham acupoints for auricular therapy. In fact, the choice of sham acupoints has been debated in acupuncture studies targeting both body and auricular sites.

Even if the existence and location of specific ear acupoints can be established, there is still a need to determine whether stimulation of those points has some effect on modulating Qi energy (if that exists) and/or other phenomena that might impact pain. Then, it must be empirically determined how those particular effects play a role in altering disease or pain states in the body. Since none of this has been scientifically validated, the prior probability (ie, clinical plausibility) of auricular therapy remains quite low.

Clinical Evidence Insufficient & Inconclusive

It should be recognized that the specific mechanisms of action for many pain therapies, including some pharmacologic agents, has not been well determined and the plausibility of their effects may seem vague. The concept of plausibility — or prior probability as a component of Bayesian inference — takes into account principles of biology and natural science, the quality and strength of previous research (if any), the many biases that may have influenced research outcomes and/or how investigators interpreted and reported their results, and even the quality of journals in which studies were published. When the prior probability is judged as being low, it requires substantial good quality and compelling clinical evidence to overcome this deficit.

While there has been considerable research on acupuncture, to date there have been few systematic reviews and meta-analyses of well-designed RCTs examining auriculotherapies for pain. All have failed to demonstrat the greater level of evidence as proof necessary to overcome the lack of scientific plausibility; for example….

  1. In the largest systematic review to date, a research team primarily from the University of North Carolina assessed 17 RCTs examining auriculotherapy for pain management (8 perioperative, 4 acute, and 5 chronic pain) [Asher et al. 2010]. The studies used a variety of techniques, including ear acupuncture using needles with and without electrical stimulation, laser auriculotherapy, transdermal electrical nerve stimulation (TENS) of ear structures, and one using auricular acupressure. Control treatments included sham auriculotherapy, placebo pill, and standard medical care.

    Results of the data meta-analysis, which incorporated only 12 of the studies, indicated moderate-to-large and statistically significant effect sizes favoring auriculotherapy over control interventions for reducing pain intensity and supplemental analgesic use. For example, the effect size (standardized mean difference, SMD) for pain reduction in all pain groups combined compared with controls was 1.55; 95% Confidence Interval 0.85-2.28; 8 studies analyzed. (For unexplained reasons, the single study of ear acupressure for acute pain was dropped from all analyses).

    These were impressive results; however, 65% (11/17) of the studies were rated as poor-to-fair quality and only 3 studies enrolled 50 or more subjects per group. Most important, the studies of acute and chronic pain had extremely high heterogeneity (I² = 85.60% and 91.93%, respectively), suggesting the individual trials were so incongruent that a meta-analysis probably should not have been conducted. Similarly, heterogeneity for all pain groups combined (noted above) was I² = 88.05%, making that analysis and its favorable outcome of dubious validity. [For a discussion of systematic review and meta-analysis concepts, including heterogeneity, see the Pain-Topics UPDATE article here.]

    The meta-analysis of 5 studies examining perioperative pain demonstrated low heterogeneity and moderately favorable outcomes for auriculotherapy (SMD = 0.54). Although, 3 of the studies were rated as being of only fair quality and all but 2 studies had fewer than 50 subjects per group. Smaller studies (<50 participants) in meta-analyses have been recently noted to inflate the true effect size by as much as 48% [Dechartres et al. 2013].
     
     
  2. An earlier systematic review of auricular acupuncture for postoperative pain control was able to uncover 9 RCTs fulfilling inclusion criteria [Usichenko et al. 2008]. In 8 of the trials, auricular acupuncture was superior to control conditions; however, none of the trials were rated as being of good quality. A common failing was a lack of therapist blinding as to treatment group, which may have skewed outcomes in favor of the acupuncture intervention. Only 2 trials had a minimum of 50 subjects per group, and 3 had less than 20 per group.

    Five of the 8 trials examined electroacupuncture, which some believe may produce nonspecific effects, due to nerve stimulation, that are unrelated to needle placement and could confound results in pain studies. Recognizing the lack of quality and extreme heterogeneity across studies, the researchers did not attempt a data meta-analysis as they had planned — unlike in the review/meta-analysis described immediately above. Overall, the researchers conclude, “The evidence that auricular acupuncture reduces postoperative pain is promising but not compelling.”
     
     
  3. To date, there appears to be only a single Cochrane Systematic Review of auriculotherapy for pain, and this focused on any type of ear acupuncture in adult patients with cancer-related pain [Paley et al. 2011]. The researchers’ extensive literature search uncovered 3 qualifying RCTs (total 204 participants) for review. There was high risk of bias in 2 studies because of low methodological quality.

    The single high quality trial compared auricular acupuncture with auricular acupuncture at “placebo points” or with noninvasive Vaccaria seeds attached at sham acupoints. Participants in the true acupuncture group had lower pain scores at a 2-month follow-up than either the placebo or ear-seeds group. However, a lack of blinding in the ear-seeds group, since seeds were attached using tape (as in the Yeh et al. 2013 study described above), may have biased results in favor of acupuncture.

    A second trial compared ear acupuncture with medication and concluded that both methods were effective in controlling pain, although acupuncture seemed slightly more effective. The third study compared acupuncture, point-injection, and medication in participants with stomach cancer. Long-term pain relief was reported for both acupuncture and point-injection compared with medication during the last 10 days of treatment. Although both studies had positive results favoring acupuncture, the reviewers note that those outcomes should be viewed with caution due to methodological limitations, small sample sizes, poor reporting, and inadequate analysis.

    The Cochrane reviewers had planned to pool data to estimate overall measures of effect and to calculate the number-needed-to-treat for benefit, but this was not possible due to heterogeneity across studies. In sum, they concluded that, “There is insufficient evidence to judge whether acupuncture is effective in treating cancer pain in adults.”

Although some of the evidence points in the direction of auriculotherapy having some benefits for pain management, the preponderance of evidence appears to lack the quality and robustness necessary for overcoming this CAM modality’s lack of plausibility (ie, prior probability for exerting beneficial effects). Auricular therapy, most commonly ear acupuncture, also has been used for many other conditions — drug dependence, smoking cessation, insomnia, anxiety or depression, and others — and the supportive evidence has been mixed in terms of quality and clearly-demonstrated efficacy [Usichenko et al. 2008].

No doubt there are abundant anecdotal accounts attesting to the beneficial effects individual patients have experienced from auriculotherapy of one type or another. And, as is always the case, even in the least successful clinical trials a certain percentage of patients self-report benefits; although, whether or not those effects can be attributed directly to the treatment intervention itself is often unknown.

The mission of science-based medicine as described above is to consider data from individual clinical trials within a larger context that first takes into account all that is known about factors that may influence the plausibility of the treatment for exerting beneficial effects. This can be especially critical when examining the validity of CAM therapies, which by definition are considered to be apart from mainstream medicine. Clearly, more and better evidence is still needed to properly assess and judge the value of auriculotherapy for pain.

REFERENCES:
> Andersson E, Persson AL, Carlsson CP. Are auricular maps reliable for chronic musculoskeletal pain disorders? Acupunct Med. 2007;25(9):72-79 [
abstract].
> Ascher GN, Jonas DE, Coeytaux RR, et al. Auriculotherapy for Pain Management: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Alternative Complementary Med. 2010;16(10):1097-1108 [
PDF here].
> Dechartres A, Trinquart L, Boutron I, Ravaud P. Influence of trial sample size on treatment effect estimates: meta-epidemiological study. BMJ. 2013;346:f2304 [
abstract here].
> Ernst E. Auricular Acupuncture. CMAJ. 2007;176(9):1307 [
access here].
> Paley CA, Johnson MI, Tashani OA, Bagnall AM. Acupuncture for cancer pain in adults. Cochrane Database of Systematic Reviews 2011, Issue 1. Art. No.: CD007753 [
abstract here].
> Usichenko TI, Lehmann CH, Ernst E. Auricular acupuncture for postoperative pain control: a systematic review of randomized clinical trials. Anaesthesiology. 2008;63(12):1343-1348 [
article here].
> Yeh CH, Chien LC, Balaban D, et al. A Randomized Clinical Trial of Auricular Point Acupressure for Chronic Low Back Pain: A Feasibility Study. Evidence-Based Complementary Alternative Med. 2013;2013:1-9 [
article PDF here].

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