Acupuncture Therapy as an Evidence-Based Nonpharmacologic Strategy for Comprehensive Acute Pain Care: The Academic Consortium Pain Task Force White Paper Update

Abstract Background A crisis in pain management persists, as does the epidemic of opioid overdose deaths, addiction, and diversion. Pain medicine is meeting these challenges by returning to its origins: the Bonica model of multidisciplinary pain care. The 2018 Academic Consortium White Paper detailed the historical context and magnitude of the pain crisis and the evidence base for nonpharmacologic strategies. More than 50% of chronic opioid use begins in the acute pain care setting. Acupuncture may be able to reduce this risk. Objective This article updates the evidence base for acupuncture therapy for acute pain with a review of systematic reviews and meta-analyses on postsurgical/perioperative pain with opioid sparing and acute nonsurgical/trauma pain, including acute pain in the emergency department. Methods To update reviews cited in the 2018 White Paper, electronic searches were conducted in PubMed, MEDLINE, CINAHL, and the Cochrane Central Register of Controlled Trials for “acupuncture” and “acupuncture therapy” and “acute pain,” “surgery,” “peri-operative,” “trauma,” “emergency department,” “urgent care,” “review(s) ,” “systematic review,” “meta-analysis,” with additional manual review of titles, links, and reference lists. Results There are 22 systematic reviews, 17 with meta-analyses of acupuncture in acute pain settings, and a review for acute pain in the intensive care unit. There are additional studies of acupuncture in acute pain settings. Conclusion The majority of reviews found acupuncture therapy to be an efficacious strategy for acute pain, with potential to avoid or reduce opioid reliance. Future multicenter trials are needed to clarify the dosage and generalizability of acupuncture for acute pain in the emergency department. With an extremely low risk profile, acupuncture therapy is an important strategy in comprehensive acute pain care.


Introduction
Medical pain management is in crisis. Pain is pervasive and has been inadequately addressed by strategies including the escalation of prescription opioids that created a tragic increase in overdose deaths, addiction, and diversion. The rising costs of pain care and managing adverse effects of that care have prompted action from state and federal agencies including the Veterans Health Administration (VHA) [1], the U.S. Department of Veterans Affairs (VA) and the Department of Defense (DOD) [2], the National Institutes of Health (NIH) [3], the U.S. Food and Drug Administration (FDA) [4], and the Centers for Disease Control and Prevention (CDC) [5]. There has been pressure for pain medicine to shift away from an overreliance on opioids and overutilized procedures and surgeries toward more comprehensive pain care that includes evidence-based nonpharmacologic strategies. Comprehensive pain care programs build on the foundation developed by John Bonica, the father of pain medicine, and are further supported by the intervening decades of research into nonpharmacologic strategies [6].
The evidence base for acupuncture therapy is extensive. Acupuncture is supported or recommended as part of comprehensive pain care by the U.S. Agency for Healthcare Research and Quality (AHRQ) [7], the U.S. Food and Drug Administration (FDA) [8], the U.S. Department of Health and Human Services (HHS) [9], and the Joint Commission TJC [10,11]. The American Academy of Family Physicians endorsed the American College of Physicians (ACP) Guidelines recommending acupuncture as a first option for acute, subacute, and chronic low back pain (LBP) [12,13]. A retrospective claims-based study found that initial visits to chiropractors, physical therapists, or acupuncturists for new-onset LBP substantially decreased early and long-term use of opioids [14]. A retrospective analysis of 427,966 patients with new-onset neck pain and back pain found that patients who saw these conservative therapists, compared with those who had primary care visits, were 72-91% less likely to fill an opioid prescription in the first 30 days and 41-87% less likely to continue filling prescriptions for 1 year [15]. Although the claims data do not indicate pain severity or duration, the authors controlled for comorbidities through the use of the Elixhauser Index, which has served as a proxy for complexity in other studies. Conversely, people with acute neck pain who initially saw an emergency department (ED) physician had the highest odds of opioid use during the first 30 days [15].
Perioperative opioid prescribing has been associated with persistent opioid use after surgery [16]. As of 2017, more than 50% of chronic opioid use began in the acute care setting, after surgery, or for treatment of acute injury-related pain [17]. The probability of long-term opioid use increases after as few as 5 days of prescribed opioids as the initial treatment of pain; the probability that patients will remain on opioids for the long term is the highest when treatment is initiated with long-acting opioids [18]. Although opioid overdose deaths began to decrease slightly in 2018 [19], they rose to an all-time high in 2019 [20]. By the end of 2020, accelerated by the coronavirus disease 2019 (COVID-19) pandemic, opioid overdose deaths increased by more than 35% from 2019 [20][21][22].
Tapering, which may or may not include cessation of opioids, has been a key strategy to reduce the risks and harms of opioids. However, dose tapering is often a lengthy and time-consuming process, and attempts at rapid tapering of doses are associated with unintended consequences, risks, and patient suffering [23,24]. Even low-dose opioid use for more than 3 months increases the risk of addiction 15-fold [25]. Sustained opioid dependence is also associated with declining function and exacerbation of pain states (hyperalgesia) secondary to mechanisms of the action of opioids [26,27]. Reducing reliance on opioids for acute pain in the ED depends not only on avoidance of prescribing opioids [25,28] but also on supporting access to effective acute pain care strategies. Transforming the system of pain care to a responsive comprehensive model necessitates that options for treatment and collaborative care be evidence based and include effective nonpharmacologic strategies that have the advantage of reduced risks of adverse events and addiction liability. The 2018 Academic Consortium White Paper [6] detailed the historical context and magnitude of the current pain problem, including individual, social, and economic impacts, as well as the challenges of pain care for patients and a health care workforce engaging in prevalent strategies that are not entirely based on current evidence [29].
The present article is the first in a series of articles to update the evidence base for nonpharmacologic therapies that are effective in acute pain [6]. The present article provides a review of reviews and meta-analyses of acupuncture for acute pain, encompassing postsurgical/perioperative pain with opioid sparing and acute nonsurgical/trauma pain, including acute pain in the ED and primary care setting.

Methods
To update and detail the literature cited in the 2018 White Paper [6] on nonpharmacologic strategies for comprehensive pain care, specifically research on acupuncture for acute pain, a search for systematic reviews (SRs), either with meta-analyses (SRMs) or without meta-analyses, was conducted for articles published through December 2020 in PubMed, MEDLINE, CINAHL, and the Cochrane Central Register of Controlled Trials for "acupuncture" and "acupuncture therapy" and "acute pain," "surgery," "peri-operative," "trauma," "emergency department," "urgent care," "review(s) ," "systematic review," "meta-analysis," with additional manual review of titles, links, and reference lists. We included articles published in peer-reviewed journals for which access to data was possible, and we excluded reviews when data or original articles could not be accessed (e.g., articles published in Chinese). Additionally, we detail research articles published since the publication of the SRs that would help inform researchers, clinicians, and policy makers on the current state of research.

Results
Twenty-two SRs were selected for review, including 17 with meta-analyses of acupuncture in acute pain settings and a review for pain in the intensive care unit (ICU). Details of SRs and SRMs are represented in Tables 1, 2

Acupuncture Therapy for Acute Pain
Acupuncture is understood as the insertion and manipulation of fine solid-core needles at specified points or combinations of points on the body. "Acupuncture therapy" derives from the traditional East Asian paradigm recognizing the interrelationship of organs, body points, and channels, as well as associated symptoms, dysfunction, and disease. Depending on the definition of the scope of practice in each state, acupuncture often includes treating by means of mechanical, thermal, or electrical stimulation; by the insertion of needles; or by the application of heat, pressure, or other forms of stimulation. In practice, acupuncture needling is deployed by first assessing a complex intersection of body organs, function, presentation, and interaction with a patient. It also is often done in combination with other therapies, such as palpation, Tui na, Gua sha, cupping, moxibustion, e-stim, auricular treatment, herbal medicine, and recommendations on diet, exercise, self-reflection, and meditative movement like Tai chi. Acupuncture therapy, therefore, includes an evaluation and decision-making process, acupuncture needling, accompanying therapies, and recommendations that engage a patient in self-care.
Significant research has focused on acupuncture in the treatment of pain. An SRM of immediate analgesic effects (13 randomized controlled trials [RCTs], n ¼ 1,077) found that acupuncture was associated with greater immediate pain relief 30 minutes or less after the end of a single treatment than the pain relief reported with sham or analgesic injections [30]. A large individual patient data meta-analysis (39 trials) of 20,827 patients with chronic pain found acupuncture to be significantly better than sham treatment or usual care, with 85% retention of treatment benefit 1 year following a course of care [31,32]. Patients with more severe pain at baseline improved more from acupuncture treatment than did those with lower levels of pain, compared with sham or non-acupuncture controls [33].
To be clear, the severity of pain is a predictor of response to acupuncture in chronic pain-i.e., the worse the pain, the better the response [33]. The immediate analgesia from a single acupuncture treatment provides better pain relief than does sham or analgesic injection, making acupuncture especially beneficial for acute pain, with opioid-sparing potential in hospital settings [30]. The largest hospital accreditation organization in the United States, The Joint Commission, has revised its pain mandate, which was originally introduced in 2000. Effective January 1, 2018, The Joint Commission requires its accredited hospitals and facilities to provide nonpharmacologic strategies for pain as a scorable Element of Performance [10]. In support of these efforts, the present narrative review includes SRs and SRMs of acupuncture for inpatient postoperative pain, as well as for acute pain not related to surgery, acute pain in an ED setting, and acute pain in primary care [6]. We include the details of the effect sizes and quality of reviews as reported by the authors, but we do not systematize authors' reporting of results.

Acupuncture Therapy for Postoperative Pain
In multiple SRMs, acupuncture was found to be effective in reducing postsurgical pain compared with sham acupuncture, controls, and usual care, with a reduction in opioid need (21% opioid reduction at 8 hours, 23% at 24 hours, and 29% at 72 hours post surgery) and with a lowered incidence of opioid-related side effects such as nausea, dizziness, sedation, pruritus, and urinary retention [34][35][36]. An SRM found that acupuncture after total knee arthroplasty reduced pain and was associated with delayed opioid use [37]. An SRM of perioperative auricular acupuncture found reduced postoperative pain and need for analgesic use compared with sham or standardof-care controls [38]. Another SRM on perioperative auricular therapies found benefit for pain and intraoperative body mass-adjusted fentanyl amount but did not find prolonged time to first analgesic request in total hip arthroplasty [39]. An SRM of auricular acupuncture for acute and postsurgical pain found that it provided immediate pain relief and benefit at 48 hours, was equivalent to analgesics, and had fewer side effects [40]. These findings indicate the potential to reduce hospital readmission due to uncontrolled pain. (See Table 1.) A 2015 SRM of acupuncture point stimulation for postoperative pain (59 RCTs; n ¼ 4,578) showed significantly improved visual analog scale (VAS) pain scores, with a further benefit of reduced total morphine consumption [34]. Still, a 2016 clinical practice guideline on postoperative pain management by the American Pain Society, the American Society of Regional Anesthesia and Pain Medicine, and the American Society of Anesthesiologists' Committee on Regional Anesthesia Peri-incisional stimulation was superior in reducing opioid consumption at 24 hours, whereas distal acupoint stimulation reduced opioid-related adverse effects, including nausea and dizziness. The pain intensity on movement at postoperative 4 hours was lower in distal stimulation. Both reduced postoperative opioid consumption at 24 hours.
incisional stimulation is safe and effective for postoperative pain and opioid sparing. They could be alternative or adjunct analgesic intervention.
More studies, larger sample size, and direct comparison needed in future.
(continued)  (continued) did neither "recommend nor discourage" acupuncture therapy as part of recommended multimodal postoperative pain care. The guideline recommendation was based on only six studies that used active sham arms [41], which are not inert controls and therefore constitute a flawed methodology [42,43]. A subsequent SRM (2016) supported the use of acupuncture as adjuvant therapy in treating postoperative pain and for reducing opioid use [35]. A 2019 SR found that distal acupuncture needling compared favorably with peri-incisional transcutaneous electrical nerve stimulation in pain reduction and opioid sparing for patients having open abdominal surgery [44]. Trials published since 2016 include a double-blind placebo-controlled trial in which intraoperative electrical stimulation of acupuncture points reduced intraoperative opioid requirements, postoperative pain, and duration of stay in the post-anesthesia care unit [45]. Another doubleblind placebo-controlled trial showed that the addition of transcutaneous electrical acupoint stimulation (application of electrical stimulation at acupuncture points) to usual care for minimally invasive lung cancer surgery reduced pain, reduced patient-controlled intravenous analgesic attempts, and reduced nausea and vomiting, which supports transcutaneous electrical acupoint stimulation as a feasible option for sedation and postoperative analgesia in thoracoscopic pulmonary resection [46].
Additionally, acupuncture was effective, safe, and well tolerated for post-tonsillectomy pain in children, with no significant side effects [47].
Acupuncture Therapy for Acute Pain in the ED/ICU As of 2021, for acute pain in the ED or urgent care setting, there were six SRs of acupuncture [50][51][52][53], of which three had meta-analyses (Table 2) [51,53,54]. Of these, one was for ear acupuncture alone [54]. Reviews included trials of acupuncture in the treatment of various acute pain conditions and injuries in adults and children in the ED, including acute LBP, acute neck pain, and acute ankle sprain; other musculoskeletal pain conditions, fractures, and nonpenetrating injuries; acute abdominal pain, appendicitis pain, renal colic, acute headache and migraine, acute dental pain, and acute pharyngitis.
One SRM included 19 RCTs and 11 observational studies and reported that acupuncture provided effective analgesia for most acute pain conditions in the ED while being noninferior to selected analgesia medications and providing statistically significant, clinically meaningful, and improved levels of patient satisfaction with respect to pain relief in the emergency setting [51]. The authors concluded that acupuncture was low cost and low risk with high patient satisfaction. In addition, there was one review of nonpharmacologic approaches to pain in the ICU, including acupuncture (see Table 3) [55].
Among studies not in SRs or SRMs (Table 4), a trial of patients in the ED found acupuncture's benefit to be comparable to pharmacotherapy for acute LBP (n ¼ 270) or ankle sprain (n ¼ 166) and found that acupuncture was safe [56]. In an observational study of 1,008 patients including children in a surgery ward, acupuncture given as first aid immediately after or optimally within 48 hours of a burn injury reduced pain, reddening, pigmentation, scarring, and post-traumatic stress disorder, which commonly follows traumatic burns [57]. Two randomized trials found that acupuncture for acute pain in the ED performed better than titrated or intravenous morphine, with minimal adverse effects [58,59].   Acupuncture is feasible and acceptable for acute pain patients in ED. Patient-reported pain, stress, and anxiety scores all significantly improved after acupuncture, with similar benefits seen regardless of whether any pain medication also was received.
Receiving only opioids during ED visit was not associated with improved pain scores. AEs not reported.
(continued)  Studies also reported high acceptability for acupuncture by patients with acute pain in the ED, when measured [56,60,61]. A retrospective study of patients with acute pain in the ED found that acupuncture produced a decrease in pain comparable to that produced by analgesics, with the additional benefits of reduction in anxiety as well as high acceptability among both medical providers and patients (Table 5) [62]. Seventy-five percent of providers referred for acupuncture, and 90% of patients agreed to acupuncture. When details were reported in studies, acupuncture sessions for acute pain in the ED averaged 10-30 minutes [58,63], with mean session durations of 23-24 minutes [60,62], and they did not disrupt ED course of care [60][61][62].
Acupuncture for acute pain in the ED is a developing area of research focus, based on single treatments during a narrow window of time. The details in Table 2 include outcome measures in addition to comparators.

Acupuncture for Acute LBP
There is evidence that acupuncture is effective for acute LBP in the short term (for 3 months or less) and on a small to moderate magnitude [81]. The ACP recommends acupuncture as a first-line treatment for acute and subacute LBP on the basis of their 2017 SRM (11 RCTs, n ¼ 1,163; actually n ¼ 1,139) [13,82]. That review was based primarily on a 2013 SRM by Lee et al. (11 RCTs,n ¼ 1,139) [82] that found acupuncture to be more effective than sham for acute LBP, but not for function, and comparable to nonsteroidal anti-inflammatory drugs (NSAIDs) [84]. Hasegawa et al. compared a Japanese scalp needling technique with traditional Chinese body acupuncture. The body acupuncture was not detailed but was not an "inert" intervention and so not a true sham control. The trial used one acupuncturist, a specialist in the scalp technique. Although the scalp technique showed benefit relative to body acupuncture in some measures, the results are questionable on the basis of the problematic design [83]. Vas et al. reported real and sham acupuncture to be superior to placebo at 3 months but equal to sham and placebo compared with medication alone at 12 months [85]. However, the study was powered only to detect differences between true acupuncture and the medication control group, where true acupuncture was superior to medication control. It was not powered relative to sham or placebo. Moreover, points used in the sham group are reported in the literature to be effective for LBP, making the sham arm an active acupuncture treatment [86]. Inclusion of Hasegawa et al. and Vas et al. in the ACP review is problematic and potentially misleading given these sham control design limitations.
The benefit of acupuncture for acute LBP is also informed by trials in the ED or urgent care setting. A multicenter equivalence, noninferiority RCT (n ¼ 528) of acupuncture for acute LBP in the ED found acupuncture to be safe, acceptable, and comparable to medications (n ¼ 270) (Table 4) [56]. A 2020 study (n ¼ 167) of a single abbreviated acupuncture treatment (8-9 minutes) for acute LBP that used hand points, movement, and several back points showed that it provided no advantage in pain relief compared with medications but did shorten the time to recovery from 14 to 9 days [74]. Although this recovery time benefit reached the authors' threshold, inexplicably, they reported it as not clinically significant.
The abbreviated auricular treatment known as battlefield acupuncture (BFA) did not provide additional benefit for acute pain, including acute LBP, in the ED [73]. There may be an advantage to more comprehensive acupuncture treatment that is responsive to individual patient presentations [56] over rote abbreviated techniques like BFA [73,74]. Moreover, BFA has been marketed as a "battlefield" option for acute pain, but it has not been studied in that setting. It is used primarily for chronic pain within the Veterans Health Administration outpatient care. Although BFA has benefited from auriculotherapy research [87], it has not been studied relative to other auricular protocols, nor is there any proven advantage of ASP V R needles (ASP: Aiguille SemiPermanent needles Sedatelec, Chemin des Mûriers 69540 Irigny, France) over other intradermal needles or ear seeds for extended auricular therapy, as has been claimed by BFA Seminars [88,89]. Rather, the "harpoon"-shaped needles [90], which are designed to embed in the chondral layer of the ear, could increase the risk of harms [91]. Auricular acupressure with Vaccaria seeds fixed to ear points has been shown to be as effective as, if not more effective than, any retained intradermal needles, with a greatly reduced risk of harms [87].
Trials of acupuncture for specific kinds of acute back pain also illuminate its potential. An SRM on acute pain in the ED that included three trials of acupuncture for renal colic found acupuncture to be as effective as medication with fewer side effects (n ¼ 38) [92], making it a potent option for immediate renal colic pain while avoiding the risks of NSAIDs or acetaminophen (n ¼ 121) [93]. Acupuncture was as effective as Dolantin (meperidine) but superior to Scopolamine (hyoscine) in another trial on renal colic (n ¼ 240), with onset time to pain relief significantly earlier for acupuncture and with greatly reduced adverse reactions [94]. Since the 2017 SRM, another trial (n ¼ 115) found acupuncture to be superior to titrated morphine for renal colic in the ED, with significantly sooner onset of pain relief (50% reduction), deeper pain relief, and greatly reduced adverse effects [58].
Acupuncture Therapy for Acute Headache and Migraine Acupuncture has been studied for acute migraine [97], migraine prophylaxis and prevention, and impact on medical expenditure [80]. Table 7 details the SRs and SRMs that evaluated acupuncture for acute headache/migraine. Although existing research indicates that acupuncture could be a potential strategy for acute migraine, where its benefit exceeds that of sham acupuncture [29,98], comparing acupuncture with protocol medications in the ED setting presents unique challenges. Acupuncture is not readily available in ED settings in the United States to conduct research, but more importantly, standard medical protocols preclude engaging acupuncture as a strategy for acute migraine in the ED [99]. For example, opioids are one standard option in the ED that precludes an acupuncture intervention, even though the evidence base for opioids' effectiveness and safety for acute migraine remains limited [29]. Where migraine and headache carry a significant global economic burden [100], real-world data from a 10-year national cohort study in Taiwan showed that in patients with migraine who received acupuncture treatment, medical expenditures on emergency care and hospitalization were significantly lower than those of the group without acupuncture treatment [80]. A review of 10 years of RCTs of acupuncture vs various controls in the treatment of migraine (49 trials) found that acupuncture reduces symptoms of migraine and improves quality of life [101]. The meta-analysis showed that acupuncture reduces headache frequency more than no treatment or medications, but the quality of evidence was low. For acute migraine (three trials), real acupuncture had a greater effect on reducing headache-related pain as measured by visual analog scale (VAS) score, earlier onset and longer duration of headache relief, and greater clinical effectiveness immediately after treatment compared with the sham acupuncture control. To reduce migraine symptoms and frequency as well as medical expenditures for migraine-related emergency care and hospitalizations, authors recommend combining acupuncture with usual care [80].

Discussion
The need for evidence-based comprehensive pain care strategies is based on insufficient management of acute pain, continued reliance on opioids for acute pain, the risk associated with opioids, and the ongoing rise in opioid deaths. This review of reviews and meta-analyses supports acupuncture therapy as a viable strategy for acute pain care.

Acute Perioperative, ICU, and ED Pain
Reviews of acupuncture for acute perioperative pain related to various surgeries, including major surgeries, are listed in Table 1. Eleven SRs, 10 of which have metaanalyses, detail the feasibility and benefits of acupuncture. Nine reviews also tracked a reduced need for analgesic medication, including opioids. This is a substantial finding, given the risk of even short-term opioid use for acute pain [18].
For acute pain in the ED, six SRs, three of which have meta-analyses, demonstrate increasing interest in and feasibility and acceptability of acupuncture in the ED (Table 2) and ICU (Table 3). Table 5 details pilot, observational, retrospective, or qualitative studies on acupuncture's reduction of acute pain, high level of acceptance, and low risk of adverse events [60,62,[75][76][77][78][79][80].
Additional trials that evaluated acupuncture for acute pain in the ICU for surgical patients, inpatients, or patients in the ED are detailed in Table 4. Two studies evaluated acupuncture for pain in intubated ICU patients: one using electrical stimulation on needles inserted into acupuncture points [65] and the other using transcutaneous electrical nerve stimulation on acupuncture points [68]. The former found a marked reduction in the dosage of the sedative drug (midazolam) needed for the pain and discomfort of mechanical intubation [65]. The latter found a reduction in pain and in analgesic and sedation medication [68].
Three studies evaluated a trademarked, abbreviated version of auricular therapy, called BFA, for acute pain, with mixed results. A small study found the addition of BFA for acute LBP to be feasible and effective [69], on par with auricular therapy in general [87]. In other studies, BFA for acute pain in lower-extremity surgery (n ¼ 233) and for acute abdominal, low back, or limb pain in the ED (n ¼ 90) was found to be ineffective [70,73]. Another trial using a different abbreviated acupuncture protocol for acute LBP also found no benefit [74]. However, a larger multicenter trial using a more robust acupuncture protocol for acute pain in the ED (n ¼ 528) found that acupuncture provided analgesia comparable to that provided by medication for acute LBP and ankle sprain [56].
Two additional studies evaluated acupuncture as a nonpharmacologic pain strategy in the acute or perioperative setting. Acupuncture for pediatric/adolescent patients (n ¼ 182) reduced pain [71]. The other study of perioperative adults (n ¼ 1,127) treated with acupuncture resulted in reduced pain, nausea, and anxiety [72].

Acute LBP and Migraine
Four reviews of acupuncture for acute LBP, three of which had meta-analyses, are detailed in Table 6. The most recent review and meta-analysis (2021) [96] found that acupuncture significantly benefits acute LBP symptoms, including a reduction in analgesic medication.
Finally, Table 7 details seven acupuncture reviews for acute migraine: two with meta-analyses and two with overviews of meta-analyses. Acupuncture had a significantly larger effect than sham [29,102,103] and a larger effect than medications [103][104][105]. Acupuncture appears to be more effective than no treatment or sham in the prevention of acute migraine, with potential as a valid option in the ED [98]. Although a review of acupuncture for menstrual migraine found a reduction in mean headache intensity from pooled data, it did not find acupuncture to reduce monthly migraine frequency, duration, or analgesic use [106].

Limitations
This narrative review allows for the inclusion of diverse articles with substantial findings on acupuncture for acute pain across various clinical settings, allowing clinicians and policy makers to review the breadth and depth of the literature. Some of the cited SRMs include trials that compared acupuncture with active sham interventions, a problematic methodology wherein controls that are not "inert" can produce physiological changes [31,42,43,107,108]. When reporting on these studies, we indicate the authors' quality assessments, but in some cases, they are at risk of underestimating the true value of acupuncture because of the active nature of the sham acupuncture used [42]. Details of effect sizes and the quality of reviews are included as reported by the studies' authors, but it is beyond the scope of the present narrative review to systemize authors' reporting of results.
The potential for acupuncture to avoid or reduce opioid use in acute pain is reported in some reviews, and these data should not be undervalued. As few as 5 days of prescribed opioids as the initial treatment of pain increases the probability of long-term opioid use [18]. Even the Centers for Disease Control and Prevention recommends non-opioid and nonpharmacologic options as a first line of treatment for acute postsurgical pain [16]. Against the background of the ongoing crisis of opioids, addiction, and death due to opioids, metrics on analgesic use, including opioids and NSAIDs, should be encouraged as a clinically meaningful outcome measure in future studies. Future multisite trials to clarify the scope, timing, and generalizability of acupuncture for acute pain the ED are recommended. On the basis of research that previously established the advantage of multidisciplinary pain care, future research must focus on individual as well as combination strategies for comprehensive pain care, which include evidence-based nonpharmacologic strategies in the acute pain care setting.

Acupuncture Therapy Safety
Acupuncture has a low risk of adverse events. More specifically, the associated effects of acupuncture have been categorized as secondary benefits, such as feeling relaxed, elated, or tired or having improved mood and sleep. The National Institutes of Health Consensus Statement on Acupuncture published in 1998 found that ". . . the incidence of adverse effects is substantially lower than that of many drugs or other accepted procedures for the same conditions" [109]. SRs and surveys have clarified that acupuncture is safe when performed by appropriately trained practitioners [110][111][112][113][114][115][116][117], with infrequent minor side effects, such as feeling relaxed, elated, or tired or having sensation or itching at the point of insertion [114]. Rare serious complications, such as infection or pneumothorax, are directly related to insufficient training [115,116,118]. Safe use of acupuncture has also been established in vulnerable populations, including children [110,[119][120][121] and pregnant women [122][123][124]. Active military service members who accessed acupuncture for chronic pain had a reduced risk of longterm adverse outcomes [125].
Research needs to continue to carefully track and report any adverse events associated with acupuncture and compare them with adverse events associated with medications used, such as opioids. Acupuncture's reduced risk is apparent in general, but one article serves as a relevant example. In the management of acute pain in the ED, acupuncture (n ¼ 150) was compared with titrated morphine (n ¼ 150) [59]. Of the 300 participants, adverse effects were experienced by 89 (29.3%) patients: 85 (56.6%) in the morphine group and 4 (2.6%) in the acupuncture group. Primary adverse events in the morphine group were dizziness, nausea, and vomiting. Acupuncture had a better success rate, with faster resolution to 50% reduction of pain than was seen in the morphine group.

Frequency, Dosage, and Timing of Nonpharmacologic Interventions for Inpatient and Acute Pain Care
Inpatient acupuncture therapy is usually delivered by a licensed independent practitioner, such as an acupuncturist, and is generally given as a daily treatment for the term of the inpatient stay, with referral for outpatient care follow-up. ED settings allow for a single treatment only. A session of inpatient or ED acupuncture care can last 20-60 minutes, with 30-45 minutes being typical. A session would likely include an interview assessment, palpation, point location, needling that may or may not include "de qi" response, resting with needles in place, needle removal and disposal, reevaluation, and recommendations. Needle retention times vary and could be 15-25 minutes depending on whether one aspect of the body or more is treated. If the front and back of the body are treated, needle retention might be 10-20 minutes for each side. If only one aspect is treated, needle retention might be longer. Body acupuncture typically involves points both local to and distal from the problem area.
Abbreviated treatments result in less optimal outcomes. For example, the limited auricular protocol BFA was not effective for acute abdominal pain, acute LBP, or limb trauma pain in the ED [73]. Modified BFA was also not effective as an adjunct for pain relief in lower-extremity surgery [70]. Another ED trial used an abbreviated 10-minute acupuncture treatment for acute LBP with usual care vs usual care alone, finding no difference in pain relief [74].
There are evidence-based data on the dosage and frequency of acupuncture for acute pain, and more research will be beneficial to further define the optimal frequency, dosage, and timing of care: What constitutes an optimal intervention in terms of session time, number of points palpated and needled, and needle retention time, and with what additional hands-on therapies? Parameters of effective acupuncture treatment for chronic pain could inform acute pain care. For example, in a large individual patient data meta-analysis (39 trials, n ¼ 20,827) 95% of trials included local and distal points, 94% aimed to obtain "de qi," 69% used 5-14 acupoints in a session (21% used 15-20 acupoints), 50% had mean session durations of 20-29 minutes, and 47% had mean session durations of 30 minutes or more [31]. The only patient characteristic that predicted outcome was severity of pain at baseline, wherein patients reporting more severe pain at baseline experienced more benefit from acupuncture compared with either sham control or non-acupuncture control [33]. These findings from such a large study may be generalizable to acute pain care.

Multimodal Approach to Acute Pain Care
The era of the promise and promotion of opioids coincided with a retraction of insurance coverage for multidisciplinary pain care strategies, which in turn created a barrier to access to and funded research of nonpharmacologic therapies [126,127]. Multimodal pain care is now recognized as the optimal, inclusive, and responsive approach to patients experiencing pain: inclusive of all evidence-based therapies, including effective nonpharmacologic strategies, and responsive to patients' diverse and evolving needs [127]. Evidence-based nonpharmacologic therapies are recommended in comprehensive pediatric and adult pain care [10,128,129]. Multimodal pain care is recommended by the American Pain Society in their guidelines for postoperative pain management [41]. Effective nonpharmacologic strategies are recommended by the ACP in their guidelines for acute LBP [13]. Comprehensive multimodal pain care must include effective nonpharmacologic strategies such as acupuncture in the inpatient and acute care setting, with a seamless referral system to support ongoing care once a patient is discharged. Nevertheless, as clearly stated in the review of back pain by Cherkin et al, ". . . Despite improved knowledge about the benefits and harms of treatments for chronic back pain in the past several decades, there is a large and consequential mismatch between treatments found safe and effective and those routinely covered by health insurance . . . The barriers to change identified in the IOM (Institute of Medicine) and Lancet reports make it clear that deficiencies in our health care delivery and payment models are centrally involved in the continued failure to improve care for back pain" [130]. This deficit applies equally to all types of pain. There is a pervasive failure to align insurance coverage to ensure access to evidence-based, safe, and effective pain treatments [131].

Acupuncture Biomechanisms
Scientific discoveries over the past several decades have demonstrated complex and robust biological mechanisms for the therapeutic effects of acupuncture. A full review of the biomechanism literature is not within the scope of the present article, and we aim only to highlight some of the most significant contributions of recent science. Research on acupuncture's impact on the musculoskeletal system includes evidence that acupuncture needle insertion stimulation influences connective tissue and fascia, collagen production, and fibroblast alignment and activity [132][133][134]. Acupuncture has also been shown to reduce inflammation locally, which in turn impacts pain processing by the central nervous system [135][136][137]. There is robust research showing how acupuncture stimulates neuroplastic changes that are known to interfere with the processes of central sensitization that are well recognized to perpetuate chronic pain. The impact on the central and peripheral nervous systems includes neurochemical alterations of the endogenous opioid [138][139][140] and endocannabinoid systems [141,142].
Neuroimmune mechanisms include alterations in the nuclear factor kappa B pathway and in the TRPV1 and TRPV2 channels of mast cells, as well as reduced levels of substance P (SP), neurokinin-1 receptor, interleukin-6, interleukin-1b, and tumor necrosis factor-a [143], thereby inhibiting the release of excitatory neurotransmitters while promoting the release of inhibitory neurotransmitters from neurons and glial cells. Acupuncture also regulates neuroinflammatory substances that inhibit microglial crosstalk [144,145].
Central mechanisms of acupuncture include deactivation of the limbic system, which is important for emotion and internal homeostasis, which impact chronic pain [146][147][148]. Functional magnetic resonance imaging evidence demonstrates beneficial modulation of the maladaptive alterations in somatosensory cortical maps that have been shown to accompany chronic pain states and interfere with optimal motor recruitment patterns [149,150].
As pain and physiology research have evolved, discoveries have demonstrated the interconnected roles of the immune system, the central and peripheral nervous systems, and all organ systems in the phenomena of nociception and its interpretation by the brain. This level of interconnectedness requires comprehensive strategies to understand pain, assess it, and deliver care. As iterated by John Bonica since the 1940s, pain care requires attention to mind and body and is best delivered through comprehensive strategies that were the cornerstone of his vision for pain treatment [151]. Evidence-based therapies such as acupuncture therapy have a vital role to play in comprehensive pain care.

Summary
Our narrative review includes 22 SRs, of which 17 have meta-analyses, and it supports the feasibility and benefit of acupuncture therapy as an effective standalone or adjunct intervention in acute perioperative pain and acute pain in the ED or urgent care setting. The evidence supporting effectiveness, safety, reduced need for opioids and NSAIDs, and improved patient satisfaction is a compelling reason for acupuncture therapy to be covered for acute pain by public and private insurance. Policy barriers preventing licensed acupuncturists from being Medicare-billing providers need to be addressed. Health care practitioners and administrators need training in the evidence base for acupuncture therapy, and they need to advocate for policy initiatives that remedy systemic reimbursement barriers to evidence-based comprehensive pain care strategies. The support, promotion, and dissemination of ongoing research into the expanding role of effective nonpharmacologic treatments for pain will need to continue to address both the short-and long-term therapeutic and economic impact of comprehensive pain care practices. Multimodal pain care is now recognized as the optimal, inclusive, and responsive approach to patients experiencing pain: incorporating all evidencebased therapies, including effective nonpharmacologic strategies is responsive to patients' diverse and evolving needs.