The ACTTION-APS-AAPM Pain Taxonomy (AAAPT) Multidimensional Approach to Classifying Acute Pain Conditions

Virtual Reality in Acute and Chronic Pain Medicine: An Updated Review

PURPOSE OF REVIEW

This review critically analyzes the recent literature on virtual reality's (VR) use in acute and chronic pain management, offering insights into its efficacy, applications, and limitations.

RECENT FINDINGS

Recent studies, including meta-analyses and randomized controlled trials, have demonstrated VR's effectiveness in reducing pain intensity in various acute pain scenarios, such as procedural/acute pain and in chronic pain conditions. The role of factors such as immersion and presence in enhancing VR's efficacy has been emphasized. Further benefits have been identified in the use of VR for assessment as well as symptom gathering through conversational avatars. However, studies are limited, and strong conclusions will require further investigation. VR is emerging as a promising non-pharmacological intervention in pain management for acute and chronic pain. However, its long-term efficacy, particularly in chronic pain management, remains an area requiring further research. Key findings highlight that VR programs vary in efficacy depending on the specificity of the origin of pain.

Thermoresponsive Polymeric Hydromorphone Prodrug Provides Sustained Local Analgesia without Apparent Adverse Effects

The extensive use of opioids for chronic pain management has contributed significantly to the current opioid epidemic. While many alternative nonopioid analgesics are available, opioids remain the most potent analgesics for moderate to severe pain management. In addition to the implementation of multimodal analgesia, there is a pressing need for the development of more effective and safer opioids. In this study, we developed a thermoresponsive N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-based hydromorphone (HMP) prodrug (ProGel-HMP, HMP content = 16.2 wt %, in base form). The aqueous solution of ProGel-HMP was free-flowing at 4 °C but became a hydrogel when the temperature was raised to ≥37 °C, allowing sustained local retention when administered in vivo. When tested in the destabilization of the medial meniscus (DMM) mouse model of osteoarthritis (OA), ProGel-HMP was retained after intra-articular injection in the OA knee joint for at least 2 weeks postinjection, with low extra-articular distribution. ProGel-HMP was not detected in the central nervous system (CNS). A single dose of ProGel-HMP produced rapid and sustained joint pain resolution for greater than 14 days when compared to saline and dose-equivalent HMP controls, likely mediated through peripheral μ-opioid receptors in the knee joint. Systemic analgesia effect was absent in the DMM mice treated with ProGel-HMP, as evident in the lack of difference in tail flick response between the ProGel-HMP-treated mice and the controls (i.e., Healthy, Saline, and Sham). Repeated dosing of ProGel-HMP did not induce tolerance. Collectively, these data support the further development of ProGel-HMP as a potent, safe, long-acting and nonaddictive analgesic for better clinical pain management.

The Impact of Exercise Prescription Variables on Intervention Outcomes in Musculoskeletal Pain: An Umbrella Review of Systematic Reviews

BACKGROUND

Musculoskeletal pain conditions are the largest contributors to disability and healthcare burden globally. Exercise interventions improve physical function and quality of life in individuals with musculoskeletal pain, yet optimal exercise prescription variables (e.g. duration, frequency, intensity) are unclear.

OBJECTIVE

We aimed to examine evidence gaps, methodological quality and exercise prescription recommendations in systematic reviews of exercise for musculoskeletal pain.

METHODS

In our prospectively registered umbrella review, PubMed, SPORTDiscus, Cochrane Database of Systematic Reviews, EMBASE, and CINAHL were searched from inception to 14 February 2023. Backward citation tracking was performed. We included peer-reviewed, English language, systematic reviews and meta-analyses of randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that compared exercise with conservative treatment, placebo or other exercise interventions in adults with musculoskeletal pain. Data were extracted from the following groups of reviews based on their reporting of exercise prescription data and analysis of the relationship between prescription variables and outcomes: (1) those that did not report any exercise prescription data, (2) those that reported exercise prescription data but did not perform a quantitative analysis and (3) those that performed a quantitative analysis of the relationship between exercise prescription variables and outcomes. Outcome measures were physical function, pain, mental health, adverse effects and adherence to treatment. AMSTAR-2 (A MeaSurement Tool to Assess systematic Reviews) was used to assess methodological quality.

RESULTS

From 6757 records, 274 systematic reviews were included. 6.6% of reviews did not report any exercise prescription data, and only 10.9% quantitatively analyzed the relationship between prescription variables and the outcome(s). The overall methodological quality was critically low in 85% of reviews.

CONCLUSION

High methodological quality evidence is lacking for optimal exercise training prescription variables in individuals with musculoskeletal pain. To better inform practice and evidence gaps, future systematic reviews should (1) identify optimum exercise prescription variables, for example, via dose-response (network) meta-analysis, (2) perform high-quality reviews per AMSTAR-2 criteria and (3) include outcomes of mental health, adverse events and exercise adherence.

PROSPERO REGISTRATION NUMBER

CRD42021287440 ( https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021287440 ).

Ibuprofen for acute postoperative pain in children

BACKGROUND

Children often require pain management following surgery to avoid suffering. Effective pain management has consequences for healing time and quality of life. Ibuprofen, a frequently used non-steroidal anti-inflammatory drug (NSAID) administered to children, is used to treat pain and inflammation in the postoperative period.

OBJECTIVES

1) To assess the efficacy and safety of ibuprofen (any dose) for acute postoperative pain management in children compared with placebo or other active comparators. 2) To compare ibuprofen administered at different doses, routes (e.g. oral, intravenous, etc.), or strategies (e.g. as needed versus as scheduled).

SEARCH METHODS

We used standard Cochrane search methods. We searched CENTRAL, MEDLINE, Embase, CINAHL and trials registries in August 2023.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in children aged 17 years and younger, treated for acute postoperative or postprocedural pain, that compared ibuprofen to placebo or any active comparator. We included RCTs that compared different administration routes, doses of ibuprofen and schedules.

DATA COLLECTION AND ANALYSIS

We adhered to standard Cochrane methods for data collection and analysis. Our primary outcomes were pain relief reported by the child, pain intensity reported by the child, adverse events, and serious adverse events. We present results using risk ratios (RR) and standardised mean differences (SMD), with the associated confidence intervals (CI). We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

We included 43 RCTs that enroled 4265 children (3935 children included in this review). We rated the overall risk of bias at the study level as high or unclear for 37 studies that had one or several unclear or high risk of bias judgements across the domains. We judged six studies as having a low risk of bias across all domains. Ibuprofen versus placebo (35 RCTs) No studies reported pain relief reported by the child or a third party, or serious adverse events. Ibuprofen probably reduces child-reported pain intensity less than two hours postintervention compared to placebo (SMD -1.12, 95% CI -1.39 to -0.86; 3 studies, 259 children; moderate-certainty evidence). Ibuprofen may reduce child-reported pain intensity, two hours to less than 24 hours postintervention (SMD -1.01, 95% CI -1.24 to -0.78; 5 studies, 345 children; low-certainty evidence). Ibuprofen may result in little to no difference in adverse events compared to placebo (RR 0.79, 95% CI 0.51 to 1.23; 5 studies, 384 children; low-certainty evidence). Ibuprofen versus paracetamol (21 RCTs) No studies reported pain relief reported by the child or a third party, or serious adverse events. Ibuprofen likely reduces child-reported pain intensity less than two hours postintervention compared to paracetamol (SMD -0.42, 95% CI -0.82 to -0.02; 2 studies, 100 children; moderate-certainty evidence). Ibuprofen may slightly reduce child-reported pain intensity two hours to 24 hours postintervention (SMD -0.21, 95% CI -0.40 to -0.02; 6 studies, 422 children; low-certainty evidence). Ibuprofen may result in little to no difference in adverse events (0 events in each group; 1 study, 44 children; low-certainty evidence). Ibuprofen versus morphine (1 RCT) No studies reported pain relief or pain intensity reported by the child or a third party, or serious adverse events. Ibuprofen likely results in a reduction in adverse events compared to morphine (RR 0.58, 95% CI 0.40 to 0.83; risk difference (RD) -0.25, 95% CI -0.40 to -0.09; number needed to treat for an additional beneficial outcome (NNTB) 4; 1 study, 154 children; moderate-certainty evidence). Ibuprofen versus ketorolac (1 RCT) No studies reported pain relief or pain intensity reported by the child, or serious adverse events. Ibuprofen may result in a reduction in adverse events compared to ketorolac (RR 0.51, 95% CI 0.27 to 0.96; RD -0.29, 95% CI -0.53 to -0.04; NNTB 4; 1 study, 59 children; low-certainty evidence).

AUTHORS' CONCLUSIONS

Despite identifying 43 RCTs, we remain uncertain about the effect of ibuprofen compared to placebo or active comparators for some critical outcomes and in the comparisons between different doses, schedules and routes for ibuprofen administration. This is largely due to poor reporting on important outcomes such as serious adverse events, and poor study conduct or reporting that reduced our confidence in the results, along with small underpowered studies. Compared to placebo, ibuprofen likely results in pain reduction less than two hours postintervention, however, the efficacy might be lower at two hours to 24 hours. Compared to paracetamol, ibuprofen likely results in pain reduction up to 24 hours postintervention. We could not explore if there was a different effect in different kinds of surgeries or procedures. Ibuprofen likely results in a reduction in adverse events compared to morphine, and in little to no difference in bleeding when compared to paracetamol. We remain mostly uncertain about the safety of ibuprofen compared to other drugs.

Postoperative Psychological Predictors for Chronic Postsurgical Pain After a Knee Arthroplasty: A Prospective Observational Study

OBJECTIVE

Chronic postsurgical pain (CPSP) is a significant adverse effect shown in around 20% of people who had undergone a knee arthroplasty (KA). Psychological risk factors have emerged as significant and potentially modifiable risk factors for its development. However, there is still little evidence when assessing these factors during the acute postoperative period. This study aimed to assess the predictive value of postoperative pain catastrophizing, pain-related fear of movement, anxiety, depression, and pain attitudes in developing CPSP after KA.

METHODS

A 6-month follow-up prospective observational study design was used. The study sample comprised 115 people who underwent a KA due to painful primary osteoarthritis. Measures of pain catastrophizing, pain-related fear of movement, anxiety, depression, and pain attitudes were obtained 1 week after surgery. CPSP was set at an intensity of ≥30 using a 100-mm visual analog scale at 3 and 6 months after surgery.

RESULTS

Analysis revealed that baseline pain intensity, pain catastrophizing, pain-related fear of movement, anxiety, depression, and maladaptive pain attitudes were significant predictors of chronic pain at 3 and 6 months after surgery in a univariate analysis. However, at 3 months after surgery, only pain intensity and pain catastrophizing were predictors in the final multivariate model forecasting disturbing pain. Moreover, 6 months after surgery, pain intensity and distrust in medical procedures remained independent predictors. Most of the psychological factors can be grouped into a single dimension defined as pain-related psychological distress.

CONCLUSION

The results suggest that postoperative pain intensity, pain catastrophizing, and pain attitudes are independent predictors for CPSP after KA.

IMPACT

Postoperative cognitive and emotional factors should be considered alongside pain intensity during postoperative rehabilitation after KA because they could influence the development of CPSP.

Diclofenac for acute postoperative pain in children

BACKGROUND

Many children undergo various surgeries, which often lead to acute postoperative pain. This pain influences recovery and quality of life. Non-steroidal anti-inflammatory drugs (NSAIDs), specifically cyclo-oxygenase (COX) inhibitors such as diclofenac, can be used to treat pain and reduce inflammation. There is uncertainty regarding diclofenac's benefits and harms compared to placebo or other drugs for postoperative pain.

OBJECTIVES

To assess the efficacy and safety of diclofenac (any dose) for acute postoperative pain management in children compared with placebo, other active comparators, or diclofenac administered by different routes (e.g. oral, rectal, etc.) or strategies (e.g. 'as needed' versus 'as scheduled').

SEARCH METHODS

We used standard, extensive Cochrane search methods. We searched CENTRAL, MEDLINE, and trial registries on 11 April 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in children under 18 years of age undergoing surgery that compared diclofenac (delivered in any dose and route) to placebo or any active pharmacological intervention. We included RCTs comparing different administration routes of diclofenac and different strategies.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were: pain relief (PR) reported by the child, defined as the proportion of children reporting 50% or better postoperative pain relief; pain intensity (PI) reported by the child; adverse events (AEs); and serious adverse events (SAEs). We presented results using risk ratios (RR), mean differences (MD), and standardised mean differences (SMD), with the associated confidence intervals (CI).

MAIN RESULTS

We included 32 RCTs with 2250 children. All surgeries were done using general anaesthesia. Most studies (27) included children above age three. Only two studies had an overall low risk of bias; 30 had an unclear or high risk of bias in one or several domains. Diclofenac versus placebo (three studies) None of the included studies reported on PR or PI. We are very uncertain about the benefits and harms of diclofenac versus placebo on nausea/vomiting (RR 0.83, 95% CI 0.38 to 1.80; 2 studies, 100 children) and any reported bleeding (RR 3.00, 95% CI 0.34 to 26.45; 2 studies, 100 children), both very low-certainty evidence. None of the included studies reported SAEs. Diclofenac versus opioids (seven studies) We are very uncertain if diclofenac reduces PI at 2 to 24 hours postoperatively compared to opioids (median pain intensity 0.3 (interquartile range (IQR) 0.0 to 2.5) for diclofenac versus median 0.7 (IQR 0.1 to 2.4) in the opioid group; 1 study, 50 children; very low-certainty evidence). None of the included studies reported on PR or PI for other time points. Diclofenac probably results in less nausea/vomiting compared to opioids (41.0% in opioids, 31.0% in diclofenac; RR 0.75, 95% CI 0.58 to 0.96; 7 studies, 463 participants), and probably increases any reported bleeding (5.4% in opioids, 16.5% in diclofenac; RR 3.06, 95% CI 1.31 to 7.13; 2 studies, 222 participants), both moderate-certainty evidence. None of the included studies reported SAEs. Diclofenac versus paracetamol (10 studies) None of the included studies assessed child-reported PR. Compared to paracetamol, we are very uncertain if diclofenac: reduces PI at 0 to 2 hours postoperatively (SMD -0.45, 95% CI -0.74 to -0.15; 2 studies, 180 children); reduces PI at 2 to 24 hours postoperatively (SMD -0.64, 95% CI -0.89 to -0.39; 3 studies, 300 children); reduces nausea/vomiting (RR 0.47, 95% CI 0.25 to 0.87; 5 studies, 348 children); reduces bleeding events (RR 0.57, 95% CI 0.12 to 2.62; 5 studies, 332 participants); or reduces SAEs (RR 0.50, 95% CI 0.05 to 5.22; 1 study, 60 children). The evidence certainty was very low for all outcomes. Diclofenac versus bupivacaine (five studies) None of the included studies reported on PR or PI. Compared to bupivacaine, we are very uncertain about the effect of diclofenac on nausea/vomiting (RR 1.28, 95% CI 0.58 to 2.78; 3 studies, 128 children) and SAEs (RR 4.52, 95% CI 0.23 to 88.38; 1 study, 38 children), both very low-certainty evidence. Diclofenac versus active pharmacological comparator (10 studies) We are very uncertain about the benefits and harms of diclofenac versus any other active pharmacological comparator (dexamethasone, pranoprofen, fluorometholone, oxybuprocaine, flurbiprofen, lignocaine), and for different routes and delivery of diclofenac, due to few and small studies, no reporting of key outcomes, and very low-certainty evidence for the reported outcomes. We are unable to draw any meaningful conclusions from the numerical results.

AUTHORS' CONCLUSIONS

We remain uncertain about the efficacy of diclofenac compared to placebo, active comparators, or by different routes of administration, for postoperative pain management in children. This is largely due to authors not reporting on clinically important outcomes; unclear reporting of the trials; or poor trial conduct reducing our confidence in the results. We remain uncertain about diclofenac's safety compared to placebo or active comparators, except for the comparison of diclofenac with opioids: diclofenac probably results in less nausea and vomiting compared with opioids, but more bleeding events. For healthcare providers managing postoperative pain, diclofenac is a COX inhibitor option, along with other pharmacological and non-pharmacological approaches. Healthcare providers should weigh the benefits and risks based on what is known of their respective pharmacological effects, rather than known efficacy. For surgical interventions in which bleeding or nausea and vomiting are a concern postoperatively, the risks of adverse events using opioids or diclofenac for managing pain should be considered.

Quantitative Global Survey Results of Acute Back Pain Sufferers Across Four Countries

Background

Surveys of back pain sufferers in the United States, China, Russia, and Germany were performed to better understand self-reported causes of acute nonspecific back pain and acute lower back pain among individuals engaging in sports and their preferred treatments.

Methods

In each country, 1000 participants were surveyed (Step 1) to identify a population of nonspecific acute back pain sufferers, understand pain and treatment characteristics, and generate profiles for individuals with long-lasting (≥7 days) acute lower back pain. Subsequently, 200 participants with acute lower back pain episodes (7-21 days) and sports participation were identified in each country and completed surveys (Step 2) about sociodemographic, pain, treatment characteristics, and causes/triggers of long-lasting acute lower back pain episodes.

Results

In the United States, China, Russia, and Germany, respectively, 59%, 49%, 61%, and 63% of respondents reported ≥1 episode of nonspecific acute back pain in the previous 6 months. Average numbers of monthly nonspecific acute back pain episodes in the United States, Russia, Germany, and China were 2.5, 1.8, 1.3, and 0.8, respectively. Prevalence of acute lower back pain associated with sports/leisure activities ranged from 20% (Russia and Germany) to 46% (China). Onset of long-lasting acute lower back pain was between ages 30 and 33 years, limiting usual activities and reducing walking distance in 60% to 85% of respondents across all countries. Acute lower back pain started post-exercise within the first day for ≥75% of respondents. Most popular nonprescription and prescription treatments for acute lower back pain were creams/gels in Russia, creams/gels and oral painkillers in Germany, oral painkillers in the United States, and hot/cold patches in China.

Conclusion

These results help to better understand acute back pain triggers, features, and treatment preferences among sports participants in different countries. Further research is warranted to develop preventative strategies.

Trial Registration

Not applicable.

Adaptive changes in sensorimotor processing in patients with acute low back pain

In low back pain (LBP), primary care and secondary prevention of recurrent and persistent LBP are not always successful. Enhanced understanding of neural mechanisms of sensorimotor processing and pain modulation in patients with acute LBP is mandatory. This explorative fMRI study investigated sensorimotor processing due to mechanosensory stimulation of the lumbar spine. We studied 19 adult patients with acute LBP (< 4 weeks of an acute episode) and 23 healthy controls. On a numeric rating scale, patients reported moderate mean pain intensity of 4.5 out of 10, while LBP-associated disability indicated mild mean disability. The event-related fMRI analysis yielded no between-group differences. However, the computation of functional connectivity resulted in adaptive changes in networks involved in sensorimotor processing in the patient group: Connectivity strength was decreased in the salience and cerebellar networks but increased in the limbic and parahippocampal networks. Timewise, these results indicate that early connectivity changes might reflect adaptive physiological processes in an episode of acute LBP. These findings raise intriguing questions regarding their role in pain persistence and recurrences of LBP, particularly concerning the multiple consequences of acute LBP pain. Advanced understanding of neural mechanisms of processing non-painful mechanosensations in LBP may also improve therapeutic approaches.

Applying the Rapid OPPERA Algorithm to Predict Persistent Pain Outcomes Among a Cohort of Women Undergoing Breast Cancer Surgery

Persistent postmastectomy pain after breast surgery is variable in duration and severity across patients, due in part to interindividual variability in pain processing. The Rapid OPPERA Algorithm (ROPA) empirically identified 3 clusters of patients with different risk of chronic pain based on 4 key psychophysical and psychosocial characteristics. We aimed to test this type of group-based clustering within in a perioperative cohort undergoing breast surgery to investigate differences in postsurgical pain outcomes. Women (N = 228) scheduled for breast cancer surgery were prospectively enrolled in a longitudinal observational study. Pressure pain threshold (PPT), anxiety, depression, and somatization were assessed preoperatively. At 2-weeks, 3, 6, and 12-months after surgery, patients reported surgical area pain severity, impact of pain on cognitive/emotional and physical functioning, and pain catastrophizing. The ROPA clustering, which used patients' preoperative anxiety, depression, somatization, and PPT scores, assigned patients to 3 groups: Adaptive (low psychosocial scores, high PPT), Pain Sensitive (moderate psychosocial scores, low PPT), and Global Symptoms (high psychosocial scores, moderate PPT). The Global Symptoms cluster, compared to other clusters, reported significantly worse persistent pain outcomes following surgery. Findings suggest that patient characteristic-based clustering algorithms, like ROPA, may generalize across diverse diagnoses and clinical settings, indicating the importance of "person type" in understanding pain variability. PERSPECTIVE: This article presents the practical translation of a previously developed patient clustering solution, based within a chronic pain cohort, to a perioperative cohort of women undergoing breast cancer surgery. Such preoperative characterization could potentially help clinicians apply personalized interventions based on predictions concerning postsurgical pain.

Diclofenac for acute postoperative pain in children

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

To assess the efficacy and safety of diclofenac (any dose) for acute postoperative pain management in children compared with placebo, other active comparators, or diclofenac administered by either different routes (e.g. oral, rectal, etc.) or strategies (e.g. as needed versus as scheduled).

A Brief Measure Assessing Adolescents' Daily In-Hospital Function Predicts Pain and Health Outcomes at Home After Major Surgery

OBJECTIVE

Pain-related function, an important component of pain assessment, is not systematically assessed in the hospital in part because of a lack of clinically meaningful measures of pain-related function. This prospective cohort study examined whether adolescents' pain-related function during hospitalization, measured daily with the Youth Acute Pain Functional Ability Questionnaire (YAPFAQ) is associated with pain and health-related quality of life (HRQOL) 2 weeks following surgery.

DESIGN

Adolescents undergoing major musculoskeletal surgery (N = 93) completed YAPFAQ (11 items) daily for up to three days in-hospital following surgery. Adolescents self-reported health-related quality of life on the pediatric quality of life inventory and pain intensity on a NRS at baseline (pre-surgery) and two-weeks following surgery. Regression models examined mean YAPFAQ and YAPFAQ rate of change as predictors of two-week outcomes, adjusting for sex, surgery type, and baseline pain/HRQOL.

RESULTS

Higher mean YAPFAQ scores (poorer function) were associated with higher pain intensity (β  =  0.2, p = 0.04) and poorer HRQOL (β = -0.3, p = 0.01) at home 2 weeks following surgery. YAPFAQ rate of change was not associated with 2-week outcomes.

CONCLUSIONS

Implementation of the YAPFAQ with in-hospital assessments to measure pain-related function will allow more comprehensive pain assessment. In-hospital YAPFAQ scores can predict important postsurgical outcomes at home and inform post-hospital care.

PERSPECTIVE

This article provides validation of a measure of pediatric pain-related function, the Youth Acute Pain Functional Ability Questionnaire (YAPFAQ) to predict important post-hospital outcomes after surgery.

A qualitative study with orthopaedic surgeons on pain catastrophizing and surgical outcomes: shifting from a medical towards a biopsychosocial model of surgery

BACKGROUND

Pain catastrophizing (PC) moderates surgical outcomes and behavioural interventions are recommended to optimise post-operative results. Less is known about surgeons' experiences of providing care and their attitudes towards the use of interventions in practice.

OBJECTIVE

It is therefore invaluable to understand surgeons' views on how best to support patients who may be at risk of suboptimal recovery. Eleven surgeons and three registrar orthopaedic practitioners took part in semi-structured interviews within a hospital setting. The surgical decision-making process, views of PC and the use of behavioural interventions in surgical practice were explored.

RESULTS

Thematic analysis identified five themes: pain expressions and pain behaviours affect the surgeons' decision-making process, when pathologies and symptoms do not match, psychological factors pertaining to unsatisfactory outcomes, a service gap in surgical care and the acceptability of using a screening tool in surgical practice to identify patients at risk of suboptimal recovery.

CONCLUSION

Orthopaedic surgeons face challenges in identifying who is likely to reach optimal versus suboptimal outcome. Surgeons are becoming increasingly aware of patient psychological distress being detrimental to outcomes, and they support the use of behavioural interventions to optimise post-operative outcomes or stop unnecessary treatments. The surgeons accept the use of a screening tool in surgical practice with better access to support services with input from allied health professionals. A screening tool may provide great utility for identifying at risk patients, to allow for modification of surgical patients care plans.

Peripheral nerve stimulation for the management of acute and subacute post-amputation pain: a randomized, controlled feasibility trial

Introduction & aim: Temporary (60-day) percutaneous peripheral nerve stimulation (PNS) has demonstrated effectiveness for the treatment of chronic post-amputation pain, and this pilot study aims to evaluate the feasibility of temporary percutaneous PNS for the treatment of acute post-amputation pain. Patients & methods: Sixteen veterans undergoing lower extremity amputation received PNS and standard medical therapy or standard medical therapy alone. Results: The PNS group reported greater reductions in average phantom limb pain, residual limb pain and daily opioid consumption, and there were fewer participants taking opioids through 3 months post-amputation. Conclusion: This pilot study suggests that PNS is feasible in the acute postoperative period following lower limb amputation and may provide a non-pharmacologic analgesic therapy that lowers pain scores and reduces opioid consumption, and thus warrants further investigation.

Effects of Patient and Surgery Characteristics on Persistent Postoperative Pain: A Mediation Analysis

OBJECTIVE

Acute postoperative pain intensity is associated with persistent postsurgical pain (PPP) risk. However, it remains unclear whether acute postoperative pain intensity mediates the relationship between clinical factors and persistent pain.

MATERIALS AND METHODS

Participants from a mixed surgical population completed the Brief Pain Inventory and Pain Catastrophizing Scale before surgery, and the Brief Pain Inventory daily after surgery for 7 days and at 30 and 90 days after surgery. We considered mediation models using the mean of the worst pain intensities collected daily on each of postoperative days (PODs) 1 to 7 against outcomes of worst pain intensity at the surgical site endpoints reflecting PPP (POD 90) and subacute pain (POD 30).

RESULTS

The analyzed cohort included 284 participants for the POD 90 outcome. For every unit increase of maximum acute postoperative pain intensity through PODs 1 to 7, there was a statistically significant increase of mean POD 90 pain intensity by 0.287 after controlling for confounding effects. The effects of female versus male sex (m=0.212, P=0.034), pancreatic/biliary versus colorectal surgery (m=0.459, P=0.012), thoracic cardiovascular versus colorectal surgery (m=0.31, P=0.038), every minute increase of anesthesia time (m=0.001, P=0.038), every unit increase of preoperative average pain score (m=0.012, P=0.015), and every unit increase of catastrophizing (m=0.044, P=0.042) on POD 90 pain intensity were mediated through acute PODs 1 to 7 postoperative pain intensity.

DISCUSSION

Our results suggest the mediating relationship of acute postoperative pain on PPP may be predicated on select patient and surgical factors.

AAAPT Diagnostic Criteria for Acute Thoracic Surgery Pain

Patients undergoing thoracic surgery experience particular challenges for acute pain management. Availability of standardized diagnostic criteria for identification of acute pain after thoracotomy and video assisted thoracic surgery (VATS) would provide a foundation for evidence-based management and facilitate future research. The Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership with the United States Food and Drug Administration, the American Pain Society (APS), and the American Academy of Pain Medicine (AAPM) formed the ACTTION-APS-AAPM Pain Taxonomy (AAAPT) initiative to address absence of acute pain diagnostic criteria. A multidisciplinary working group of pain experts was invited to develop diagnostic criteria for acute thoracotomy and VATS pain. The working group used available studies and expert opinion to characterize acute pain after thoracotomy and VATS using the 5-dimension taxonomical structure proposed by AAAPT (i.e., core diagnostic criteria, common features, modulating factors, impact/functional consequences, and putative mechanisms). The resulting diagnostic criteria will serve as the starting point for subsequent empirically validated criteria. PERSPECTIVE ITEM: This article characterizes acute pain after thoracotomy and VATS using the 5-dimension taxonomical structure proposed by AAAPT (ie, core diagnostic criteria, common features, modulating factors, impact and/or functional consequences, and putative mechanisms).

Conditioned open-label placebo for opioid reduction after spine surgery: a randomized controlled trial

ABSTRACT

Placebo effects have traditionally involved concealment or deception. However, recent evidence suggests that placebo effects can also be elicited when prescribed transparently as "open-label placebos" (OLPs), and that the pairing of an unconditioned stimulus (eg, opioid analgesic) with a conditioned stimulus (eg, placebo pill) can lead to the conditioned stimulus alone reducing pain. In this randomized control trial, we investigated whether combining conditioning with an OLP (COLP) in the immediate postoperative period could reduce daily opioid use and postsurgical pain among patients recovering from spine surgery. Patients were randomized to COLP or treatment as usual, with both groups receiving unrestricted access to a typical opioid-based postoperative analgesic regimen. The generalized estimating equations method was used to assess the treatment effect of COLP on daily opioid consumption and pain during postoperative period from postoperative day (POD) 1 to POD 17. Patients in the COLP group consumed approximately 30% less daily morphine milligram equivalents compared with patients in the treatment as usual group during POD 1 to 17 (-14.5 daily morphine milligram equivalents; 95% CI: [-26.8, -2.2]). Daily worst pain scores were also lower in the COLP group (-1.0 point on the 10-point scale; 95% CI: [-2.0, -0.1]), although a significant difference was not detected in average daily pain between the groups (-0.8 point; 95% CI: [-1.7, 0.2]). These findings suggest that COLP may serve as a potential adjuvant analgesic therapy to decrease opioid consumption in the early postoperative period, without increasing pain.

AAAPT: Assessment of the Acute Pain Trajectory

OBJECTIVE

Define and contrast acute pain trajectories vs. the aggregate pain measurements, summarize appropriate linear and nonlinear statistical analyses for pain trajectories at the patient level, and present methods to classify individual pain trajectories. Clinical applications of acute pain trajectories are also discussed.

SETTING

In 2016, an expert panel involving the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION), American Pain Society (APS), and American Academy of Pain Medicine (AAPM) established an initiative to create a pain taxonomy, named the ACTTION-APS-AAPM Pain Taxonomy (AAAPT), for the multidimensional classification of acute pain. The AAAPT panel commissioned the present report to provide further details on analysis of the individual acute pain trajectory as an important component of comprehensive pain assessment.

METHODS

Linear mixed models and nonlinear models (e.g., regression splines and polynomial models) can be applied to analyze the acute pain trajectory. Alternatively, methods for classifying individual pain trajectories (e.g., using the 50% confidence interval of the random slope approach or using latent class analyses) can be applied in the clinical context to identify different trajectories of resolving pain (e.g., rapid reduction or slow reduction) or persisting pain. Each approach has advantages and disadvantages that may guide selection. Assessment of the acute pain trajectory may guide treatment and tailoring to anticipated symptom recovery. The acute pain trajectory can also serve as a treatment outcome measure, informing further management.

CONCLUSIONS

Application of trajectory approaches to acute pain assessments enables more comprehensive measurement of acute pain, which forms the cornerstone of accurate classification and treatment of pain.

Forty-two Million Ways to Describe Pain: Topic Modeling of 200,000 PubMed Pain-Related Abstracts Using Natural Language Processing and Deep Learning-Based Text Generation

OBJECTIVE

Recent efforts to update the definitions and taxonomic structure of concepts related to pain have revealed opportunities to better quantify topics of existing pain research subject areas.

METHODS

Here, we apply basic natural language processing (NLP) analyses on a corpus of >200,000 abstracts published on PubMed under the medical subject heading (MeSH) of "pain" to quantify the topics, content, and themes on pain-related research dating back to the 1940s.

RESULTS

The most common stemmed terms included "pain" (601,122 occurrences), "patient" (508,064 occurrences), and "studi-" (208,839 occurrences). Contrarily, terms with the highest term frequency-inverse document frequency included "tmd" (6.21), "qol" (6.01), and "endometriosis" (5.94). Using the vector-embedded model of term definitions available via the "word2vec" technique, the most similar terms to "pain" included "discomfort," "symptom," and "pain-related." For the term "acute," the most similar terms in the word2vec vector space included "nonspecific," "vaso-occlusive," and "subacute"; for the term "chronic," the most similar terms included "persistent," "longstanding," and "long-standing." Topic modeling via Latent Dirichlet analysis identified peak coherence (0.49) at 40 topics. Network analysis of these topic models identified three topics that were outliers from the core cluster, two of which pertained to women's health and obstetrics and were closely connected to one another, yet considered distant from the third outlier pertaining to age. A deep learning-based gated recurrent units abstract generation model successfully synthesized several unique abstracts with varying levels of believability, with special attention and some confusion at lower temperatures to the roles of placebo in randomized controlled trials.

CONCLUSIONS

Quantitative NLP models of published abstracts pertaining to pain may point to trends and gaps within pain research communities.

Ibuprofen Arginate for Rapid-Onset Pain Relief in Daily Practice: A Review of Its Use in Different Pain Conditions

Ibuprofen is one of the most frequently used analgesics. One of the concerns related with the oral administration of conventional ibuprofen is the relatively slow absorption, which is clinically a relative inconvenience when rapid-onset analgesic effect is required in patients suffering from acute moderate/severe pain. A new oral dosage formulation of ibuprofen containing the L-arginine salt of ibuprofen (ibuprofen arginate) has been commercialized for more than two decades, but data reported in the literature are relatively scarce. This article presents salient findings on pharmacokinetics, pharmacological activity, clinical efficacy and tolerability of ibuprofen arginate, with the purpose to provide clinicians with a summary overview of some frequent acute pain conditions, such as dental pain, dysmenorrhea, headache or postoperative pain in which ibuprofen arginate may be considered the drug of choice in individual patients.

The role of regional anaesthesia and multimodal analgesia in the prevention of chronic postoperative pain: a narrative review

Effective prevention of chronic postoperative pain is an important clinical goal, informed by a growing body of studies. Peri-operative regional anaesthesia remains one of the most important tools in the multimodal analgesic toolbox, blocking injury-induced activation and sensitisation of both the peripheral and central nervous system. We review the definition and taxonomy of chronic postoperative pain, its mechanistic basis and the most recent evidence for the preventative potential of multimodal analgesia, with a special focus on regional anaesthesia. While regional anaesthesia targets several important aspects of the mechanistic pathway leading to chronic postoperative pain, evidence for its efficacy is still mixed, possibly owing to the heterogeneity of risk profiles within the surgical patient, but also to variation in techniques and medications reported in the literature.

Managing pain in seriously ill patients with substance use disorders

ABSTRACT

Managing pain can be challenging, especially in patients with serious illnesses and a history of substance use disorders. This article discusses the challenges of addressing pain in these patients and offers perspectives regarding their clinical management.

The role of anxiety and related states in pediatric postsurgical pain

Background: Nearly 20% of children and adolescents have pain with disability 1 year after surgery, and they experience poor sleep, school absence, and decreased activities. Negative clinical, psychological, and developmental effects include greater pain medication use, longer recovery, and fear of future medical care. Research has found psychological and family influences (i.e., child and parental anxiety) on pediatric chronic postsurgical pain (CPSP), but a better understanding of the role of perioperative anxiety and its related states in predicting pediatric postsurgical pain is needed. The poor understanding of the causes of child CPSP can lead to misdiagnosis and inadequate treatment, with significant short- and long-term effects. Objectives: The aim of this review was to summarize the literature on children's perioperative anxiety and parental anxiety in relation to acute postsurgical pain, CPSP, and pain trajectories. We also examined other related psychological factors (i.e., anxiety sensitivity, catastrophizing, pain anxiety, and fear of pain) in relation to pediatric acute and chronic postsurgical pain. Lastly, we discuss the interventions that may be effective in reducing children's and parents' preoperative anxiety. Conclusions: Our findings may improve the understanding of the causes of CPSP and highlight the gaps in research and need for further study.

AAAPT Diagnostic Criteria for Acute Low Back Pain with and Without Lower Extremity Pain

OBJECTIVE

Low back pain is one of the most common reasons for which people visit their doctor. Between 12% and 15% of the US population seek care for spine pain each year, with associated costs exceeding $200 billion. Up to 80% of adults will experience acute low back pain at some point in their lives. This staggering prevalence supports the need for increased research to support tailored clinical care of low back pain. This work proposes a multidimensional conceptual taxonomy.

METHODS

A multidisciplinary task force of the ACTTION-APS-AAPM Pain Taxonomy (AAAPT) with clinical and research expertise performed a focused review and analysis, applying the AAAPT five-dimensional framework to acute low back pain.

RESULTS

Application of the AAAPT framework yielded the following: 1) Core Criteria: location, timing, and severity of acute low back pain were defined; 2) Common Features: character and expected trajectories were established in relevant subgroups, and common pain assessment tools were identified; 3) Modulating Factors: biological, psychological, and social factors that modulate interindividual variability were delineated; 4) Impact/Functional Consequences: domains of impact were outlined and defined; 5) Neurobiological Mechanisms: putative mechanisms were specified including nerve injury, inflammation, peripheral and central sensitization, and affective and social processing of acute low back pain.

CONCLUSIONS

The goal of applying the AAAPT taxonomy to acute low back pain is to improve its assessment through a defined evidence and consensus-driven structure. The criteria proposed will enable more rigorous meta-analyses and promote more generalizable studies of interindividual variation in acute low back pain and its potential underlying mechanisms.

The Impact of Music on Nociceptive Processing

OBJECTIVE

Music has been shown to modulate pain, although the impact of music on specific aspects of nociceptive processing is less well understood. Using quantitative sensory testing (QST), we assessed the impact of a novel music app on specific aspects of nociceptive processing.

DESIGN

Within-subjects paired comparison of pain processing in control vs music condition.

SETTING

Human psychophysical laboratory.

SUBJECTS

Sixty healthy adult volunteers.

METHODS

Subjects were assessed for baseline anxiety, depression, and catastrophizing using validated questionnaires. QSTs measured included 1) pain threshold and tolerance to deep muscle pressure, 2) pain with mechanical pinprick, 3) temporal summation of pain (TSP) with a repeated pain stimulus, and 4) conditioned pain modulation (CPM) with a second painful stimulus. QSTs were performed in the absence and presence of music delivered through a music app.

RESULTS

We found an increase in pressure pain thresholds in both the forearm (P = 0.007) and trapezius (P = 0.002) with music, as well as a decrease in the amount of pinprick pain (P < 0.001) and TSP (P = 0.01) with music. Interestingly, CPM was also significantly diminished (P < 0.001) in the music condition. No significant difference in cold pain, anxiety, or situational catastrophizing was observed with music. Higher baseline pain catastrophizing scores were associated with less music-induced pressure pain reduction.

CONCLUSIONS

Several measures of mechanical pain sensitivity were reduced with music. TSP, a measure of central sensitization, also decreased with music, but CPM, a measure of descending modulation of pain, was not further augmented by music.

Common Biological Modulators of Acute Pain: An Overview Within the AAAPT Project (ACTTION-APS-AAPM Acute Pain Taxonomy)

OBJECTIVE

The ACTTION-APS-AAPM Acute Pain Taxonomy (AAAPT) project relies on the identification of modulators to improve characterization and classification of acute pain conditions. In the frame of the AAAPT effort, this paper presents an overview of common biological modulators of acute pain.

METHODS

Nonsystematic overview.

RESULTS

Females may experience more acute pain than males, but the clinical significance may be modest. Increasing age is associated with decreasing analgesic requirement and decreasing pain intensity after surgery and with higher risk of acute low back pain. Racial and ethnic minorities have worse pain, function, and perceived well-being. Patients with preexisting chronic pain and opioid use are at higher risk of severe acute pain and high opioid consumption. The OPRM1 gene A118G polymorphism is associated with pain severity and opioid consumption, with modest quantitative impact. Most studies have found positive associations between pain sensitivity and intensity of acute clinical pain. However, the strength of the association is unclear. Surgical techniques, approaches, and complications influence postoperative pain.

CONCLUSIONS

Sex, age, race, ethnicity, preexisting chronic pain and opioid use, surgical approaches, genetic factors, and pain sensitivity are biological modulators of acute pain. Large studies with multisite replication will quantify accurately the association between modulators and acute pain and establish the value of modulators for characterization and classification of acute pain conditions, as well as their ability to identify patients at risk of uncontrolled pain. The development and validation of quick, bed-side pain sensitivity tests would allow their implementation as clinical screening tools. Acute nonsurgical pain requires more investigation.

Which Psychological Factors Are Involved in the Onset and/or Persistence of Musculoskeletal Pain? An Umbrella Review of Systematic Reviews and Meta-Analyses of Prospective Cohort Studies

OBJECTIVE

The objective of this study was to summarize the current status of knowledge about the longitudinal association between vulnerability or protective psychological factors and the onset and/or persistence of musculoskeletal (MSK) pain.

METHODS

PubMed, CINAHL, PsycINFO, PubPsych, Scopus, Web of Science, gray literature, and manual screening of references were searched from inception to June 15, 2019. Systematic reviews with or without meta-analysis that explored the longitudinal association between psychological factors and the onset and/or persistence of MSK pain were identified. The AMSTAR-2 tool was used to assess the risk of bias.

RESULTS

Fifty-nine systematic reviews that included 286 original research studies were included, with a total of 249,657 participants (127,370 with MSK pain and 122,287 without MSK pain at baseline). Overall, our results found that exposure to many psychological vulnerability factors such as depression, anxiety, psychological distress, and fear, among others, may increase the risk of the onset and persistence of MSK pain across time. In addition, our results also showed that a range of psychological factors considered to be "protective" such as self-efficacy beliefs, better mental health, active coping strategies, or favorable expectations of recovery may reduce the risk of the onset and persistence of MSK pain. However, all these systematic reviews were evaluated to have critically low confidence based on the AMSTAR-2 tool, indicating that findings from these reviews may be informative, but should be interpreted with caution.

DISCUSSION

The large number of methodological flaws found across reviews gives rise to a call to action to develop high-quality systematic reviews in this field.

Topical Review: State of the Field of Child Self-Report of Acute Pain

OBJECTIVE

Children experience acute pain with routine and emergent healthcare, and untreated pain can lead to a range of repercussions. Assessment is vital to diagnosing and treating acute pain. Given the internal nature of pain, self-report is predominant. This topical review reflects on the state of the field of pediatric acute pain self-report, and proposes a framework for acute pain assessment via self-report.

METHOD

We examine self-report of acute pain in preschool-age children through adolescents, and we detail a three-step process to optimize acute pain assessment.

RESULTS

The first step is to decide between a pain screening or assessment. Several 0-10 self-report scales are available for pain screenings. Assessment requires specification of the goals and domains to target. Core criteria, common features, modulating factors, and consequences of acute pain provide a framework for a comprehensive pain assessment. Whereas there are some measures available to assess aspects of these domains, there are considerable gaps. Last, it is important to integrate the data to guide clinical care of acute pain.

CONCLUSIONS

Self-report of acute pain is dominated by single-item intensity scales, which are useful for pain screening but inadequate for pain assessment. We propose a three-step approach to acute pain assessment in children. However, there is a need for measure development for a comprehensive evaluation of the core criteria, common features, modulating factors, and consequences of pediatric acute pain. In addition, there is limited guidance in merging data found in multifaceted evaluations of pediatric acute pain.

AAAPT Diagnostic Criteria for Acute Pain Following Breast Surgery

Acute pain after breast surgery decreases the quality of life of cancer survivors. Previous studies using a variety of definitions and methods report prevalence rates between 10% and 80%, which suggests the need for a comprehensive framework that can be used to guide assessment of acute pain and pain-related outcomes after breast surgery. A multidisciplinary task force with clinical and research expertise performed a focused review and synthesis and applied the 5 dimensional framework of the AAAPT (Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks [ACTTION], American Academy of Pain Medicine [AAPM], American Pain Society [APS] Pain Taxonomy) to acute pain after breast surgery. Application of the AAAPT taxonomy yielded the following: 1) Core Criteria: Location, timing, severity, and impact of breast surgery pain were defined; 2) Common Features: Character and expected trajectories were established in relevant surgical subgroups, and common pain assessment tools for acute breast surgery pain identified; 3) Modulating Factors: Biological, psychological, and social factors that modulate interindividual variability were delineated; 4) Impact/Functional Consequences: Domains of impact were outlined and defined; 5) Neurobiologic Mechanisms: Putative mechanisms were specified ranging from nerve injury, inflammation, peripheral and central sensitization, to affective and social processing of pain. PERSPECTIVE: The AAAPT provides a framework to define and guide improved assessment of acute pain after breast surgery, which will enhance generalizability of results across studies and facilitate meta-analyses and studies of interindividual variation, and underlying mechanism. It will allow researchers and clinicians to better compare between treatments, across institutions, and with other types of acute pain.

The IASP classification of chronic pain for ICD-11: chronic postsurgical or posttraumatic pain

Chronic pain after tissue trauma is frequent and may have a lasting impact on the functioning and quality of life of the affected person. Despite this, chronic postsurgical and posttraumatic pain is underrecognised and, consequently, undertreated. It is not represented in the current International Classification of Diseases (ICD-10). This article describes the new classification of chronic postsurgical and posttraumatic pain for ICD-11. Chronic postsurgical or posttraumatic pain is defined as chronic pain that develops or increases in intensity after a surgical procedure or a tissue injury and persists beyond the healing process, ie, at least 3 months after the surgery or tissue trauma. In the classification, it is distinguished between tissue trauma arising from a controlled procedure in the delivery of health care (surgery) and forms of uncontrolled accidental damage (other traumas). In both sections, the most frequent conditions are included. This provides diagnostic codes for chronic pain conditions that persist after the initial tissue trauma has healed and that require specific treatment and management. It is expected that the representation of chronic postsurgical and posttraumatic pain in ICD-11 furthers identification, diagnosis, and treatment of these pain states. Even more importantly, it will make the diagnosis of chronic posttraumatic or postsurgical pain statistically visible and, it is hoped, stimulate research into these pain syndromes.

Evaluating the psychometric properties of the Widespread Pain Index and the Symptom Severity scale in youth with painful conditions

Background

Assessing features of centralized pain may prove to be clinically meaningful in pediatric populations. However, we are currently limited by the lack of validated pediatric measures.

Aim

We examined the psychometric properties of the Widespread Pain Index (WPI) and Symptom Severity (SS) scale, to assess features of centralized pain, in youth with painful conditions from three clinical samples: (1) musculoskeletal surgery, (2) headache, and (3) chronic pain.

Methods

Participants were 240 youth aged 10-18 years (Mage=14.8, SD=1.9) who completed the WPI and SS scale. Subsets of participants also completed additional measures of pain region, pain intensity, quality of life, pain interference and physical function.

Results

Increased features of centralized pain by age were seen for the WPI (r=0.27, p<0.01) and SS scale (r=0.29, p<0.01). Expected differences in sex were seen for the WPI (sex:t₁₃₂=-3.62, p<0.01), but not the SS scale (sex:t₂₂₃=-1.73, p=0.09). Reliability for the SS scale was adequate (α=.70). Construct validity was demonstrated through relationships between the WPI and pain regions (r=.57, p<0.01), and between the SS scale and quality of life (r=-.59, p<0.01) and pain interference (r=.56, p<0.01). Criterion validity was demonstrated by differences on the WPI between the surgery sample and the headache and chronic pain samples (F_2,237=17.55, p<0.001). Comprehension of the SS scale items was problematic for some youth.

Conclusions

The WPI showed adequate psychometric properties in youth; however the SS scale may need to be modified. Our findings support the need to develop psychometrically sound instruments for comprehensive assessment of pain in pediatric samples.

A new clinical model for facilitating the development of pattern recognition skills in clinical pain assessment

Common, enigmatic musculoskeletal conditions such as whiplash-associated disorder, myofascial pain syndrome, low back pain, headache, fibromyalgia, osteoarthritis, and rotator cuff pathology, account for significant social, economic, and personal burdens on a global scale. Despite their primacy (and shared sequelae) there remains a paucity of available and effective management options for patients with both acute and chronic conditions. Establishing an accurate prognostic or diagnostic profile on a patient-by-patient basis can challenge the insight of both novice and expert clinicians. Questions remain on how and when to choose the right tool(s), at the right time(s), for the right patient(s), for the right problem(s). The aim of this paper is to introduce a new clinical reasoning framework that is simple in presentation but allows interpretation of complex clinical patterns, and is adaptable across patient populations with acute or chronic, traumatic or non-traumatic pain. The concepts of clinical phenotyping (e.g. identifying observable characteristics of an individual resulting from the interaction of his/her genotype and their environment) and triangulation serve as the foundation for this framework. Based on our own clinical and research programs, we present these concepts using two patient cases; a) whiplash-associated disorder (WAD) following a motor vehicle collision and b) mechanical low back pain.

Current methods and challenges for acute pain clinical trials

This article reviews current methods and challenges and provides recommendations for future design and conduct of clinical trials of interventions to treat acute pain.

Introduction:

The clinical setting of acute pain has provided some of the first approaches for the development of analgesic clinical trial methods.

Objectives:

This article reviews current methods and challenges and provides recommendations for future design and conduct of clinical trials of interventions to treat acute pain.

Conclusion:

Growing knowledge about important diverse patient factors as well as varying pain responses to different acute pain conditions and surgical procedures has highlighted several emerging needs for acute pain trials. These include development of early-phase trial designs that minimize variability and thereby enhance assay sensitivity, minimization of bias through blinding and randomization to treatment allocation, and measurement of clinically relevant outcomes such as movement-evoked pain. However, further improvements are needed, in particular for the development of trial methods that focus on treating complex patients at high risk of severe acute pain.