Learning Objectives/Outcomes: After participating in this CME/CNE activity, the provider should be better able to:

1. Describe the science of acupuncture.

2. Explain the proposed mechanisms of acupuncture.

3. Evaluate the evidence supporting acupuncture for pain management.

4. Identify examples of conditions in which acupuncture may be considered as part of a comprehensive pain management plan.

5. Recognize the safety profile of acupuncture.

Medications may provide only partial relief from chronic pain and can cause untoward side effects. As a result, many individuals turn to complementary health approaches as part of their pain management strategy. A review of evidence from clinical trials demonstrates that acupuncture is beneficial in helping to manage pain. Knowledge of acupuncture and its efficacy in managing certain pain conditions is important for all health care professionals involved in pain management. This article familiarizes the practitioner with the science, safety profile, mechanisms, and evidence behind the practice of acupuncture. This knowledge will help the pain practitioner in considering whether acupuncture can be part of an individual patient's comprehensive pain management plan.

Acupuncture is widely practiced by physicians and used by millions of patients in the treatment and prevention of pain.1,2 Extensive studies conducted on the use of acupuncture have demonstrated promising results, especially for painful conditions including back and knee pain and headache. However, researchers are only beginning to understand the role of acupuncture in the management and treatment of painful conditions.

Acupuncture in the United States

There is evidence that acupuncture dates back more than 3000 years to China during the Shang Dynasty. One of the first references to it appears in Sir William Osler's Principles and Practice of Medicine. Osler was taught acupuncture by Sir Sydney Ringer in England in 1873, and described many uses of the technique in his book, although there was no indication Osler saw this treatment as ancient Chinese medicine.3

However, the first widespread introduction of acupuncture to Western society did not occur until 1972, after President Richard M. Nixon developed relations with China.

James Reston, a New York Times journalist, was in China at the time of Nixon's visit and underwent an emergency appendectomy, with acupuncture used for postoperative analgesia. Reston wrote a front-page story that described how his intense postoperative pain was relieved by acupuncture, an ancient technique of Chinese medicine then unknown in the West. This article resulted in the National Institutes of Health (NIH) sending teams of scientists and clinicians to China to learn whether acupuncture anesthesia had any validity.4

Many years passed before any major medical publication on the topic appeared, although public interest grew, and acupuncturists trained in traditional Chinese medicine (TCM) set up practices. The resulting prevalence of acupuncture created a public need for a critical evaluation of the practice as a medical therapy.

In November 1997, NIH published a consensus statement addressing the use and effectiveness of acupuncture. The panel reviewed available clinical data collected from published literature to present a cohesive report on acupuncture as a therapeutic intervention in the United States. The statement supported the efficacy of acupuncture for specific conditions, such as pain, nausea, and vomiting, on the basis of the results of well-designed and appropriately controlled clinical trials.2

According to the 1997 NIH consensus statement, there were "relatively few" high-quality, randomized, controlled trials published on the effects of acupuncture. It stated, "Most of the research consisted of case reports, case series, or intervention studies with designs inadequate to assess efficacy."

The consensus stated that the studies demonstrated clear efficacy only for adult postoperative nausea and vomiting and nausea during pregnancy.

Where the statement specifically related to acupuncture and pain management, the data supported the efficacy of acupuncture for postoperative dental pain. However, a number of studies demonstrated pain relief of menstrual cramps, tennis elbow, and fibromyalgia.

Clinical experience, supported by some research, suggests that acupuncture "may be a reasonable option for ... postoperative pain and myofascial pain and low back pain."2

The NIH consensus statement formally acknowledged the role of acupuncture as an acceptable alternative or included in a comprehensive management program. The statement concluded that there was "sufficient evidence of acupuncture's value," supporting the expansion of "its use into conventional medicine." The statement goes on to encourage further studies of its physiology and clinical value.2

Since this consensus statement was released, the number of acupuncture-related NIH-funded articles has more than tripled, demonstrating substantial growth in the interest of acupuncture and its role in the health care system.

By 1998, acupuncture became the most popular complementary and alternative medicine modality prescribed by Western physicians.2,5 In 1999, NIH established the National Center for Complementary and Alternative Medicine.4 In 2002, NIH conducted the largest and most comprehensive survey of complementary and alternative medicine use by American adults. In the 2002 National Health Interview Survey, 4.1% of the respondents reported lifetime use, and 1.1% (representing 2.13 million Americans) reported recent use of acupuncture.5,6

In 2012, NIH analyzed individual patient data meta-analyses and published the findings in the Archives of Internal Medicine. Data from 29 quality randomized controlled trials (RCTs) (n = 17,922) were reviewed to assess the use of acupuncture for back and neck pain, osteoarthritis, shoulder pain, and chronic headache. The researchers demonstrated modest but statistically significant differences between acupuncture and simulated acupuncture approaches (ie, specific effects), and larger differences between acupuncture and no-acupuncture controls (ie, nonspecific effects).

The authors noted that these findings suggest that the total effects of acupuncture, as experienced by patients in clinical practice, are clinically relevant.

They also noted that their study provides the most robust evidence to date that acupuncture is more than just placebo and a reasonable referral option for patients with chronic pain.7

Philosophy of Acupuncture

The early development of acupuncture coincided with the rise and prominence of 2 widespread Chinese philosophies, Confucianism and Taoism, and is largely grounded in these philosophies.8

These 2 Chinese philosophies, particularly Taoism, emphasized the importance of understanding the laws of nature and for humans to integrate and abide by these laws rather than resist them. According to TCM, there are 2 main opposing forces within nature: yin and yang. The interaction of these 2 forces regulates the flow of "vital energy," termed qi (pronounced "chee"). In the healthy person, yin and yang are balanced and qi flows with ease, unimpeded. Disease is thought of as a result of an imbalance that leads to the slowing or the disruption of flow.9 The goal of the clinician was to maintain the body's harmonious balance both internally and in relation to the external environment.10

The ancient Chinese theory presumes that qi flows through a network of channels, known as meridians that bring qi from internal organs to the surface of the skin. Along the meridians, acupuncture points can be stimulated to correct the imbalance and restore health.4

The Standard Acupuncture Nomenclature published by the World Health Organization (WHO) listed about 400 acupuncture points and 20 meridians (12 main meridians; 8 secondary meridians) connecting most of the points. Additional acupuncture points (both on- and off-channel) have been added with time, and the total number of points has increased to at least 2000.11

Eastern medicine follows that the human body is dynamic and interconnected with the world.10 To the acupuncturist, back pain should not be evaluated as an isolated symptom, but rather must arise within a particular context. Once the nature of imbalance is determined, the acupuncture practitioner aims to shift the constitution toward balance with the use of various interventions.12

Acupuncture Techniques and Experience

Acupuncture describes a family of procedures involving stimulation of anatomic locations on the skin by a variety of techniques. Needles are inserted into specific acupoints, or locations, along channels of energy on the surface of the body, called meridians. The most prevalent and widely studied techniques include plain needling, electroacupuncture, and heat stimulation.13

* Plain needling usually involves needle insertion, followed by small manipulations in a bidirectional motion, with or without up and down movements of the needle. In TCM, effectiveness of the intervention can be measured by the elicitation of de qi. De qi is perceived by the patient as a dull ache, heaviness, mild paresthesia, or tingling, whereas the acupuncturist typically describes it as a "grasp."13

* Electroacupuncture achieves needle stimulation with a device similar to that of transcutaneous electric nerve stimulation. It can generate currents of up to 1 mA, voltage of 40 to 80 V, and frequency of 1 to 100 Hz. Stimulation is applied to the handles of inserted acupuncture needles via insulated wires and small metal clips. In pain management, the settings are usually maintained with a low amplitude of less than 5 mA and a low frequency of 1 to 20 Hz.

* Heat stimulation, or moxibustion, is a technique in which a compressed stick of the dried herb Artemisia vulgaris is burned like incense near the acupuncture point.

Other techniques are sometimes applied. They include hand pressure, low-power laser, electricity, magnets, and ultrasound. The type of intervention and level of stimulation varies with acupuncture style and between acupuncturists. Some styles, such as auricular, hand, and scalp acupuncture, limit their stimulation to a particular body part.12,14

In a typical acupuncture session, independent of technique, 5 to 20 needles are placed to connect with targeted locations.15 The duration of each session may vary, but will typically last 1 hour. All the needles are inserted into predetermined points and then left in situ for 10 to 15 minutes. During this time, the patient is instructed to relax. Needles will then be removed, signifying the end of the session. Treatments occur 1 to 2 times a week, and the total number of sessions is variable, depending on the condition, disease severity, and chronicity.12

Acupuncture treatments are usually individualized-catered to the specific patient rather than to the condition.16 Two patients with identical problems will frequently receive different treatments; point combinations can also vary between sessions. Acupuncture is often used in conjunction with other modalities for pain management.

Mechanism of Action

The mechanism of action remains unclear as to precisely how acupuncture provides analgesia. The TCM perspective cannot be used to understand the mechanistic basis, as it is not based on anatomic, physiological, or biochemical evidence. Western theories are primarily based on the presumption that acupuncture induces cytokines, hormones (eg, cortisol and oxytocin), biomechanical effects, electromagnetic effects, the immune system, and the autonomic and somatic nervous systems.4

The most thoroughly studied application of acupuncture is for pain relief. Studies performed in the 1970s and 1980s have contributed tremendously to our present understanding of the analgesic effects of acupuncture. Most studies were based on the aforementioned Western theory that acupuncture induces modulation of spinal signal transmission and supraspinal pain perception in the brain.17,18

Acupuncture has been associated with endorphin release at both spinal and supraspinal levels. In support of this theory, there is evidence that opioid antagonists block the analgesic effects of acupuncture.19 However, in contrast to this theory, the endorphin effects seem to be short-term, only lasting 10 to 20 minutes and possibly up to several days,20 whereas many acupuncture clinical trials have documented longer effects.21,22

Although it is evident that endorphin release can be induced by strongly stimulating free nerve endings or muscle afferents, the exact relationship between needle location and a specific painful condition remains unclear. Therefore, researchers have acknowledged the limitations of the endorphin-related mechanism.23

Over the last decade, advanced imaging technologies that have been introduced include positron emission tomography (PET), single-proton emission computer tomography, and functional MRI (fMRI). These powerful imaging technologies have made it possible to visualize the anatomic and functional effects of acupuncture stimulation in the brain noninvasively.4

Studies using PET and fMRI scans have demonstrated that de qi results in central neural effects, particularly in the limbic system, hypothalamus, and insula, extending to the midbrain.13

Acupuncture may result in generalized oxygenation and increased blood flow to specific areas of treatment. The stimulation of de qi also increases blood flow to skin and muscle, as detected by photoplethysmography. One study, using speckle laser blood flow scanning, interestingly demonstrated that de qi can help regulate blood flow with certain degree of channel specificity, indirectly suggesting the existence of acupuncture channels.13 Additional basic science studies demonstrate that acupuncture suppresses inflammation; any decreases in inflammation may improve physical function.24

Clinical Application

In 2003, WHO published a statement on acupuncture on the basis of published studies that listed 28 conditions for which acupuncture has been proved, through controlled trials, to be an effective treatment. Of the 28 conditions listed by WHO, 16 of those are pain related.13,25

Since 2003, research has continued to evaluate further the treatment of various conditions with acupuncture. Currently available evidence demonstrates that acupuncture seems to have potential efficacy (whether or not it has greater efficacy than sham acupuncture) in the following pain conditions:

* Low back pain;

* Knee osteoarthritis; and

* Chronic headache.

It is important to note also that acupuncture has demonstrated possible efficacy for many other nonpain conditions, including hypertension, postoperative nausea and vomiting, chemotherapy-induced nausea, seasonal allergic rhinitis, and menopausal hot flashes, but the evidence for these conditions is beyond the scope of this article.12

Challenges in Clinical Evidence for the Use of Acupuncture for Pain Conditions

It is helpful to first review common problems demonstrated among the existing acupuncture studies when evaluating current clinical evidence. Some of the obstacles encountered in randomized trials on acupuncture are not unique to the study of acupuncture: small sample size, lack of follow-up, imprecise outcomes, and improper statistical analysis. However, issues unique to acupuncture research include the following:

1. One disease state in biomedicine can correlate with many "patterns" within the Eastern medicine classification schema. Therefore, choice of acupuncture treatment may not always correlate with a given disease state.15

2. Individualized treatments used in acupuncture run counter to the standardized treatments used in randomized trials. Researchers have tried to deal with this by performing pragmatic trials (where acupuncturists are given full freedom) or trials using semistandardized treatment (where acupuncturists are assigned mandatory points but given additional individualized options). Whether this latter approach approximates real acupuncture treatments is uncertain, as few studies have reported acupuncturists' perceptions as to whether their treatments were constrained.26

3. Acupuncture entails many different styles and techniques. In the United States alone, at least 8 different styles of acupuncture are taught in the various accredited schools.27 Differences exist on the points to be needled, how the needle should be manipulated, how long the needle should be kept in, and what is the appropriate response elicited from the patient.28 Thus, it is difficult to know whether the results of a trial of a single type of acupuncture can be generalized to other types.

4. Double-blind studies are difficult to perform because practitioners are easily able to distinguish real acupuncture from sham acupuncture.

5. Delivering acupuncture is not as simple as administering pills, and much like psychotherapy and surgery, experience may play a critical role in determining outcome.

Despite these difficulties, various studies were successful in evaluating the efficacy of acupuncture compared with placebo by using a sham control procedure.

Low Back Pain

Well-designed clinical trials have demonstrated that both acupuncture and sham acupuncture are more effective than control interventions for low back pain (LBP). In a systematic review of 6 randomized trials for chronic nonspecific LBP, acupuncture was demonstrated to have a small beneficial effect in reducing pain and improving functional status compared with sham, placebo, or other passive modalities at short-term (1 month) and intermediate-term follow-up (3 and/or 6 months).29

In a systematic review of acupuncture for acute LBP that included a total of 11 RCTs (n = 1139), compared with nonsteroidal anti-inflammatory drugs, acupuncture may more effectively improve symptoms of acute LBP. Compared with sham acupuncture, acupuncture may more effectively relieve LBP (2 studies; mean difference, -9.38; 95% confidence interval: -17.00 to -1.76) but not function/disability. Acupuncture seems to be associated with few adverse effects, but the evidence is limited.30

Most recently, in 2016, the Mayo Clinic Proceedings published a review of RCTs from the MEDLINE database on complementary medicine approaches in pain management. Researchers evaluated 4 RCTs (n = 1092) on the clinical benefit of acupuncture for LBP. Cherkin et al31 reported modest but significant improvement in pain when compared with usual care. Comparison of sham acupuncture had mixed results, with 2 RCTs32,33 demonstrating no difference, and 1 RCT34 demonstrating a small but significant difference. However, Wang et al34 demonstrated a significant decrease in pain with auricular acupuncture when compared with no treatment.

Knee Osteoarthritis

Multiple clinical trials have demonstrated improved pain management with both acupuncture and sham acupuncture as compared with conservative management for knee osteoarthritis (OA). Most studies reviewed demonstrated modest, if any, benefit of verum acupuncture when compared with sham acupuncture.

A rigorous Cochrane systematic review of 16 RCTs (n = 3498) concluded that acupuncture was a viable treatment option for OA of peripheral joints, including knee OA. The Cochrane report included 12 studies on OA of the knee, 3 OA of the hip, and 1 study with mixed OA of the hip and knee. The clinical conclusion of the review is that when compared with no treatment (waiting-list control), acupuncture provides statistically and clinically significant, short-term improvements in pain and function. Compared with sham interventions, acupuncture provides small, statistically significant improvements that are of questionable clinical importance. When compared with other guideline-recommended clinical interventions (advice and exercise), acupuncture produces similar treatment effects.35

A multicenter randomized trial, including more than 1000 patients, compared 10 sessions of acupuncture, sham acupuncture, or clinician visits in patients with chronic knee OA. Rates of success were similar for acupuncture and sham acupuncture and greater than with conservative therapy (53% and 51%, compared with 29%).36

A meta-analysis of 12 RCTs (n = 1763) of acupuncture for knee OA concluded that acupuncture may have had some additional measurable benefits compared with sham acupuncture but that the differences were too small to be clinically relevant.37

Chronic Headache

A significant number of reliable clinical studies have demonstrated improvement in headache frequency after acupuncture versus no acupuncture and a small reduction when compared with sham acupuncture.

A meta-analysis of 22 randomized trials (n = 4985) evaluated the efficacy of acupuncture in preventing episodic migraines compared with no acupuncture, sham acupuncture, or prophylactic drug treatments.38 On the basis of this meta-analysis, acupuncture is associated with a moderate reduction in migraine episodes at study completion (and possibly sustained till a 6-month postrandomization follow-up) when compared with no-acupuncture groups. This difference is smaller yet statistically significant when compared with both sham acupuncture and prophylactic drug treatment at completion of treatment. Acupuncture is associated with fewer adverse outcomes relative to prophylactic drug treatment.

The primary outcome measure was migraine frequency, defined as the number of migraine days (or attacks) per month, at completion of the treatment and at 6-month follow-up. For comparisons with no acupuncture (acute abortive treatment only or "routine" care), acupuncture demonstrated a "moderate" reduction of headache frequency at study completion, with 40% of patients in the acupuncture group versus 17% in the no-acupuncture group experiencing 50% or more reduction in headache frequency. As compared with the sham acupuncture, acupuncture was associated with a small reduction in headache frequency during the study as well as at follow-up.38

It is important to note that the decreased difference in response, compared with no acupuncture, is consistent with findings from other studies that sham acupuncture is associated with clinical improvements.15

Adverse Effects

Although generally safe, acupuncture can lead to the complications (Table 1) consistent with any type of needle use. These potential complications include transmission of diseases, needle fragments left in the body, nerve damage, pneumothorax, pneumoperitoneum, organ puncture, cardiac tamponade, and osteomyelitis.40,41 Local complications may include bleeding, contact dermatitis, infection, pain, and paresthesias.40

Table 1. Adverse Events Associated With Acupuncture

Lao et al40 published a systematic review of acupuncture literature published between the years 1965 and 1999. During the period reviewed, 202 incidents were identified in 98 relevant articles reported from 22 countries. The review suggests that, "if clean needle procedure and proper needling techniques are followed, acupuncture appears to be a safe medical procedure with minimal adverse reactions." The 202 complications and adverse events reported over this 35-year period represent fewer than 6 cases per year and can be considered quite low.40 White42 subsequently performed a systematic review to determine the incidence of adverse events related to acupuncture. The review included 12 prospective studies with more than 1 million acupuncture treatments surveyed. In the review, White42 estimated that the risk of a serious adverse event from acupuncture was 0.05 per 10,000 treatments and 0.55 per 10,000 individual patients. Later prospective studies similarly concluded that the vast majority of adverse effects were minor and required little or no treatment.

Acupuncture can be considered very safe when rates of adverse effects are compared with those associated with common pharmacologic treatments. Major complications are rare and often are associated with poorly trained and unlicensed acupuncturists.

Credentialing

In the United States, the American Board of Medical Acupuncture certifies clinician acupuncturists, whereas the National Certification Commission for Acupuncture and Oriental Medicine certifies nonclinician acupuncturists.

Certifications require passing a standardized examination and demonstration of adequate training. The standard for an acupuncturist is usually between 2000 and 3000 hours of training in a 3- or 4-year program that is independently accredited.15 Although some states allow physicians to practice acupuncture without additional education, most require 200 to 300 hours of special training.

Skill Level and Licensing

Level of skill among acupuncture practitioners (both licensed and unlicensed) varies widely. Patients most often depend on recommendations or word of mouth to identify higher-quality practitioners.

Referring clinicians and patients should attempt to identify acupuncturists who use sterile techniques and needles. In the United States, acupuncturists should be certified by the National Certification Commission for Acupuncture and Oriental Medicine or the American Board of Medical Acupuncture; acupuncturists should be licensed if they are in 1 of the 40 states that have such licensure.

The ideal acupuncturist views acupuncture as a complementary modality, rather than an alternative to the conventional medical therapies. This will foster a collaborative relationship between the clinician and the acupuncturist.

Insurance Coverage in the United States

In the United States, Medicare and Medicaid do not cover acupuncture, but numerous other private insurance carriers offer some form of acupuncture coverage.43 The number of insurance carriers that cover acupuncture has increased steadily in recent history.44 Employer coverage for acupuncture increased by 14% (from 33% in 2002 to 47% in 2004), making it one of the fastest-growing complementary and alternative medicine therapies to be included as a covered service for American workers.45 There is wide variability in acupuncture coverage, ranging from a small discount to total coverage.43

However, referring physicians should be cognizant of the potential for the high cost of acupuncture. Patients should be advised on the out-of-pocket costs that can quickly accumulate, given the number of sessions frequently required for treatment of a condition.

Conclusion

Acupuncture is an ancient therapy that has been rejuvenated and has gained substantial popularity in the United States over the past 50 years. Heightened interest has driven the medical community to research acupuncture and its role in the treatment of medical conditions. Current data suggest that acupuncture may help patients manage painful conditions. Physicians and other clinicians in pain management should know enough background on acupuncture and pain management to provide acupuncturists with information necessary to have informed conversations with patients. As our knowledge and experience with acupuncture continues to develop, a multidisciplinary and collaborative approach across all types of practitioners and researchers will help further define the utility of therapeutic acupuncture for pain conditions.

References