Assay sensitivity of pain intensity versus pain relief in acute pain clinical trials: ACTTION systematic review and meta-analysis

Patient-controlled analgesia for the management of adults with acute trauma in the emergency department: A systematic review and meta-analysis

BACKGROUND

Patient-controlled analgesia (PCA) has potential as a form of analgesia for trauma patients in the emergency department (ED). The objective of this review was to evaluate the effectiveness and safety of PCA for the management of adults with acute traumatic pain in the ED. The hypothesis was that PCA can effectively treat acute trauma pain in adults in the ED, with minimal adverse outcomes and better patient satisfaction compared with non-PCA modalities.

METHODS

MEDLINE (PubMed), Embase, SCOPUS, ClinicalTrials.gov , and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched from inception date to December 13, 2022. Randomized controlled trials involving adults presenting to the ED with acute traumatic pain who received intravenous (IV) analgesia via PCA compared with other modalities were included. The Cochrane Risk of Bias tool and the Grading of Recommendation, Assessment, Development, and Evaluation approach were used to assess the quality of included studies.

RESULTS

A total of 1,368 publications were screened, with 3 studies involving 382 patients meeting the eligibility criteria. All three studies compared PCA IV morphine with clinician-titrated IV morphine boluses. For the primary outcome of pain relief, the pooled estimate was in favor of PCA with a standard mean difference of -0.36 (95% confidence interval, -0.87 to 0.16). There were mixed results concerning patient satisfaction. Adverse event rates were low overall. The evidence from all three studies was graded as low-quality because of a high risk of bias from lack of blinding.

CONCLUSION

This study did not demonstrate a significant improvement in pain relief or patient satisfaction using PCA for trauma in the ED. Clinicians wishing to use PCA to treat acute trauma pain in adult patients in the ED are advised to consider the available resources in their own practice settings and to implement protocols for monitoring and responding to potential adverse events.

LEVEL OF EVIDENCE

Systematic Review/Meta-Analyses; Level III.

A randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of a bupivacaine hydrochloride implant in patients undergoing abdominoplasty

INTRODUCTION

Surgical site infiltration with bupivacaine hydrochloride (HCl) is a standard element of postoperative analgesia for soft tissue surgeries, but results in short-lived analgesia. A novel bupivacaine implant, XARACOLL (bupivacaine HCl), is Food and Drug Administration approved for treatment of acute postsurgical pain following adult inguinal herniorrhaphy. This study examined the efficacy and safety of the bupivacaine implant (300 mg) compared with placebo for postsurgical pain after abdominoplasty.

METHODS

In this double-blind, placebo-controlled study, patients undergoing abdominoplasty were randomized to three 100 mg bupivacaine implants or three placebo collagen implants, in a 1:1 ratio, implanted intraoperatively. No other analgesics were administered into the surgical site. Patients were allowed opioids and acetaminophen for postoperative pain. Patients were followed for up to 30 days after treatment.

PRIMARY OUTCOME

the analgesic effect of the bupivacaine implants through 24 hours postsurgery, measured by the sum of time-weighted pain intensity (SPI24). Prespecified key secondary outcomes included SPI48 and SPI72, percentage of opioid-free patients through 24, 48, and 72 hours, and adverse events, which were tested sequentially to control for multiplicity (ie, if the first variable failed to reach significance, no subsequent variables were declared statistically significant).

RESULTS

The bupivacaine implant patients (n=181) reported statistically significant lower SPI24 (mean (SD) SPI24=102 (43), 95% CI 95 to 109) compared with placebo patients (n=184; SPI24=117 (45), 95% CI 111 to 123, p=0.002). SPI48 was 190 (88, 95% CI 177 to 204) for INL-001 and 206 (96, 95% CI 192 to 219) for placebo, and not significantly different between groups. The subsequent secondary variables were therefore declared not statistically significant. SPI72 was 265 (131, 95% CI 244 to 285) for INL-001 and 281 (146, 95% CI 261 to 301) for placebo. The opioid-free percentage of patients at 24, 48, and 72 hours was 19%, 17%, and 17% for INL-001 and 6.5% for placebo patients (at all timepoints). The only adverse event occurring in ≥5% of patients and for which proportion INL-001 >placebo was back pain (7.7% vs 7.6%).

CONCLUSION

The study design was limited by not containing an active comparator. Compared with placebo, INL-001 provides postoperative analgesia that is temporally aligned with the period of maximal postsurgical pain in abdominoplasty and offers a favorable safety profile.

TRIAL REGISTRATION NUMBER

NCT04785625.

OVER THE COUNTER ANALGESICS ARE EFFECTIVE IN TREATING ORTHODONTIC PAIN

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

The efficacy of analgesics in controlling orthodontic pain: a systematic review and meta- analysis. Cheng C, Xie T, Wang J. BMC Oral Health 2020; 20:259.

SOURCE OF FUNDING

The systematic review was funded by grants from the National Natural Science Foundation of China (No. 81771114 and No. 81970967). The authors have no actual or potential conflicts of interest.

TYPE OF STUDY/DESIGN

Systematic review with meta-analysis of data.

Preoperative Education for Less Outpatient Pain after Surgery (PELOPS trial) in orthopedic patients-study protocol for a randomized controlled trial

Background

Successful pain management after outpatient surgery requires proper education leading to correct decisions on the analgesics use at home. Despite different strategies adopted, up to ½ of patients receive little or no information about the treatment of postoperative pain, 1/3 of them are not able to follow postoperative analgesia instructions. This leads to higher rates of unmet needs in pain treatment, post-discharge emergency calls, and readmissions. Structured educational interventions using psychological empowering techniques may improve postoperative pain management. We hypothesize that preoperative education on use of an improved pain scale to make correct pain management decisions will improve the quality of post-operative pain management at home and reduce analgesics-related side effects.

Methods

A total of 414 patients scheduled for an outpatient orthopedic surgery (knee/shoulder arthroscopic interventions) are included in this randomized (1:1) controlled trial. Patients in the control arm receive standard information on post-discharge pain management. Patients in the experimental arm receive structured educational intervention based on the rational perception of postoperative pain and discomfort (anchoring and improved pain scale), and the proper use of analgesics. There is no difference in post-discharge analgesics regimen in both arms. Patients are followed for 30 days post-discharge, with the primary outcome expressed as total pain relief score at 5 days. Secondary outcomes include the incidence of severe pain during 30 days, changes in sleep quality (Pittsburg Sleep Quality Assessment), and patients’ perception of postoperative pain management assessed with the International Pain Outcomes questionnaire at day 30 post-discharge.

Discussion

The developed intervention, based on an improved pain scale, offers the advantages of being non-surgery-specific, is easily administered in a short amount of time, and can be delivered individually or in-group, by physicians or nurses.

Trial registration

ClinicalTrials.govNCT03754699. Registered on November 27, 2018.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06387-6.

A critical review of oliceridine injection as an IV opioid analgesic for the management of severe acute pain

INTRODUCTION

Oliceridine is a G protein-selective (biased) agonist at the μ-opioid receptor, with less recruitment of β-arrestin-2, a signaling pathway associated with opioid-related adverse events. Nonclinical evidence showed that oliceridine elicits a rapid systemic analgesic effect while attenuating opioid-related adverse events.

AREAS COVERED

Three pivotal studies in patients with moderate to severe acute pain, including two randomized, double-blind, placebo- and morphine-controlled efficacy studies following either orthopedic surgery-bunionectomy or plastic surgery-abdominoplasty; and an open-label safety study following a surgical procedure or due to a medical condition.

EXPERT OPINION

Poorly controlled acute postoperative pain is associated with poorer recovery, longer hospitalization, increased complications, and worse healthcare outcomes. Recently, oliceridine intravenous injection was approved for use in adults for the management of acute pain severe enough to require an intravenous opioid analgesic and for whom alternative treatments are inadequate. Introduction of this new IV opioid provides a valuable option to manage postoperative pain.

The effect of pre-emptive ibuprofen on post-operative pain after removal of lower third molar teeth: a systematic review

Objective To investigate the effect of pre-emptive ibuprofen on post-operative pain after lower third molar surgery.Methods A search for randomised controlled trials was undertaken across the databases Medline, Embase, Cochrane Central and Dentistry and Oral Sciences Source. Citation searching was used to supplement the database search. Inclusion and exclusion criteria were used for independent double screening by two assessors.Results A total of five randomised controlled trials were included in the review. A risk of bias assessment identified some concerns in four of the included studies. One study was assessed as having low risk of bias. The important outcomes measured were post-operative pain intensity, total pain relief, use of rescue analgesia, time to rescue analgesia and total consumption of rescue analgesia. In two trials, pre-emptive ibuprofen was shown to significantly reduce pain intensity after lower third molar surgery compared with placebo. Two trials showed no significant difference between ibuprofen and placebo groups. Pre-emptive ibuprofen was shown to provide superior pain relief compared with placebo in the one trial measuring this outcome. Where the use of rescue medication was measured as an outcome, two trials showed that pre-emptive ibuprofen was superior to placebo, one trial showed that placebo was superior to ibuprofen and two trials found no significant difference between ibuprofen and placebo groups.Conclusion Due to the inconsistency of the results, there is insufficient evidence to support the use of pre-emptive ibuprofen for management of post-operative pain after lower third molar surgery. Further research into the effects of pre-emptive analgesia on the surgical pain pathway is required.

Essential statistical principles of clinical trials of pain treatments

This article presents an overview of fundamental statistical principles of clinical trials of pain treatments. Statistical considerations relevant to phase 2 proof of concept and phase 3 confirmatory randomized trials investigating efficacy and safety are discussed, including (1) research design; (2) endpoints and analyses; (3) sample size determination and statistical power; (4) missing data and trial estimands; (5) data monitoring and interim analyses; and (6) interpretation of results. Although clinical trials of pharmacologic treatments are emphasized, the key issues raised by these trials are also directly applicable to clinical trials of other types of treatments, including biologics, devices, nonpharmacologic therapies (eg, physical therapy and cognitive-behavior therapy), and complementary and integrative health interventions.

Safety in Acute Pain Medicine-Pharmacologic Considerations and the Impact of Systems-Based Gaps

Objective

In the setting of an expanding prevalence of acute pain medicine services and the aggressive use of multimodal analgesia, an overview of systems-based safety gaps and safety concerns in the setting of aggressive multimodal analgesia is provided below.

Setting

Expert commentary.

Methods

Recent evidence focused on systems-based gaps in acute pain medicine is discussed. A focused literature review was conducted to assess safety concerns related to commonly used multimodal pharmacologic agents (opioids, nonsteroidal anti-inflammatory drugs, gabapentanoids, ketamine, acetaminophen) in the setting of inpatient acute pain management.

Conclusions

Optimization of systems-based gaps will increase the probability of accurate pain assessment, improve the application of uniform evidence-based multimodal analgesia, and ensure a continuum of pain care. While acute pain medicine strategies should be aggressively applied, multimodal regimens must be strategically utilized to minimize risk to patients and in a comorbidity-specific fashion.

Efficacy and Safety of Combination of NSAIDs and Muscle Relaxants in the Management of Acute Low Back Pain

INTRODUCTION

Low back pain is a common problem worldwide causing deterioration of health and quality of life. Low back pain is often associated with muscle spasm. We investigated the combined effect of muscle relaxants and pain killers for low back pain.

METHODS

In this open-label, prospective, multicenter study, patients with acute low back pain received a single tablet of either the fixed dose combination of chlorzoxazone 500 mg and ibuprofen 400 mg (manufacturer: Dr. Reddy's Laboratories, India) (C + I group) or ibuprofen 400 mg (I group) thrice daily for up to 7 days. Primary outcomes were improvement in pain by Visual Analogue Scale (VAS) and Summed Pain Intensity Difference (SPID) at 3 and 7 days post-treatment.

RESULTS

A total of 406 patients were included in this study. When compared to baseline, the absolute mean change in VAS scores on Day 7 was 62.39 ± 18.78 and 57.34 ± 16.29 in the C + I and I groups, respectively (P = 0.0001). In the C + I and I groups, the mean SPID at Days 3 and 7 were 51.27 ± 24.44 and 47.80 ± 22.91, and 300.82 ± 92.40 and 277.16 ± 81.83, respectively. No deaths or serious adverse events were reported. Common adverse events included gastritis, stomach pain, fever, cold, and headache. At the end of the study, excellent to good response was reported in 94.08% and 77.33% of patients in the C + I and I groups, respectively. Excellent to good tolerability was observed in 96.05% and 89.65% patients in the two groups, respectively.

CONCLUSION

Fixed dose combination of chlorzoxazone and ibuprofen demonstrated superior efficacy than ibuprofen monotherapy in acute low back pain. Both drugs were well-tolerated and should be considered as judicious therapeutic options in patients with acute low back pain.

TRIAL REGISTRATION

This trial is registered with Clinical Trial Registry of India-CTRI/2016/10/007348.

FUNDING

Dr. Reddy's Laboratories Ltd.

Human-like cutaneous neuropathologies associated with a porcine model of peripheral neuritis: A translational platform for neuropathic pain

Despite enormous investment in research and development of novel treatments, there remains a lack of predictable, effective, and safe therapeutics for human chronic neuropathic pain (NP) afflictions. NP continues to increase among the population and treatments remain a major unmet public health care need. In recent years, numerous costly (time and money) failures have occurred attempting to translate successful animal pain model results, typically using rodents, to human clinical trials. These continued failures point to the essential need for better animal models of human pain conditions. To address this challenge, we have previously developed a peripheral neuritis trauma (PNT) model of chronic pain induced by a proximal sciatic nerve irritation in pigs, which have a body size, metabolism, skin structure, and cutaneous innervation more similar to humans. Here, we set out to determine the extent that the PNT model presents with cutaneous neuropathologies consistent with those associated with human chronic NP afflictions. Exactly as is performed in human skin biopsies, extensive quantitative multi-molecular immunofluorescence analyses of porcine skin biopsies were performed to assess cutaneous innervation and skin structure. ChemoMorphometric Analysis (CMA) results demonstrated a significant reduction in small caliber intraepidermal nerve fiber (IENF) innervation, altered dermal vascular innervation, and aberrant analgesic/algesic neurochemical properties among epidermal keratinocytes, which are implicated in modulating sensory innervation. These comprehensive pathologic changes very closely resemble those observed from CMA of human skin biopsies collected from NP afflictions. The results indicate that the porcine PNT model is more appropriate for translational NP research compared with commonly utilized rodent models. Because the PNT model creates cutaneous innervation and keratinocyte immunolabeling alterations consistent with human NP conditions, use of this animal model for NP testing and treatment response characteristics will likely provide more realistic results to direct successful translation to humans.

Efficacy and safety of a triple active sore throat lozenge in the treatment of patients with acute pharyngitis: Results of a multi-centre, randomised, placebo-controlled, double-blind, parallel-group trial (DoriPha)

OBJECTIVE

The aim of this multi-centre, randomised, double-blind, placebo-controlled trial was to compare the efficacy and safety of the fixed combination of 0.5 mg tyrothricin, 1.0 mg benzalkonium chloride, and 1.5 mg benzocaine (study drug marketed as Dorithricin® ) in repeat dosing for 3 days to match placebo lozenges in the treatment of acute pharyngitis in adults.

METHODS

Patients (pts, aged ≥18 years) with acute pharyngitis, ie, non-streptococcal sore throat and moderate-to-severe pain (intensity NRS ≥ 7; VAS ≥ 50) were assigned to study drug (n = 160) or matching placebo (n = 161). Efficacy was assessed by investigator for 2 hours post initial dose (p.i.d.), and 3 days later (Visit 2). Primary efficacy endpoint was the complete resolution of throat pain and difficulty in swallowing at Visit 2 (3 days p.i.d.). Safety and local tolerability were also assessed.

RESULTS

Seventy-two hours (p.i.d.), complete resolution of throat pain and difficulty in swallowing were achieved by 44.6% patients on study drug compared with 27.2% patients on placebo (difference 17.4% (CI [5.8%; 29.7%]; 64% improvement [GEE, P = 0.0022]). Until 2 hours p.i.d., reduction in symptoms was better with study drug (P < 0.005). Treatment satisfaction was higher with study drug (patients'/investigators' assessment (78.9%/78.9% vs 55.0%/55.6% for placebo) and was well tolerated, overall safety profile was comparable to placebo.

CONCLUSION

The strength of this randomised controlled trial lies in the endpoint of complete remission after 3 days p.i.d., especially in the light of other trials addressing acute pharyngitis. The results of this study show a significant benefit of the study drug over placebo in the treatment of acute pharyngitis. Local treatment with the fixed combination (0.5 mg tyrothricin, 1.0 mg benzalkonium chloride, and 1.5 mg benzocaine) provides a rapid analgesic effect and is effective in relieving both severe throat pain as well as difficulty in swallowing associated with acute pharyngitis leading to a 64% improved complete remission within 72 hours. The triple active combination is a suitable treatment option for patients in the self-management of acute pharyngitis and sore throat.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT03323528.

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.

A Systematic Review of Labor Pain Used as an Outcome Criterion in Clinical Research

OBJECTIVES

Research on labor pain currently uses standard scores such as numerical scales as clinical outcomes, but no clear guidelines for such an assessment have appeared since a review published in 1998. We aimed to describe and estimate the quality of the methods used to assess and analyze such outcomes in a systematic review of 215 comparative studies published since then in 27 influential journals.

METHODS

In addition to a complete description, we created for each study a composite "analysis quality score" (AQS) on the basis of the methods of both measurement of pain/analgesia, and statistical analysis. AQS was tested against various factors, including a "design quality score" (DQS), created to estimate methodological quality (regardless of the analysis of pain intensity).

RESULTS

Both the AQS and its "measurement" component increased with the year of publication, as well as the DQS. The impact factor correlated only with the statistical component of the AQS, and with the DQS. However, the mean AQS and DQS were, respectively, at 43% and 75% of their maximal possible value, and these 2 scores were not correlated. The intensity of labor pain (or pain relief) was the primary outcome in 19% of the studies. Although most of the studies actually used numerical scales, the methods of analysis were heterogeneous. When a cutoff point was determined to define analgesia, this was most often 30% of the maximal value.

DISCUSSION

This review points out the need for a better standardization of the methods in this field of research.

Fulranumab in Patients With Pain Associated With Postherpetic Neuralgia and Postraumatic Neuropathy: Efficacy, Safety, and Tolerability Results From a Randomized, Double-blind, Placebo-controlled, Phase-2 Study

Supplemental Digital Content is available in the text.

Objective:

Fulranumab is an antibody that specifically neutralizes the biological activity of human nerve growth factor. This multicenter, phase-2, randomized, double-blind (DB), placebo-controlled study evaluated the analgesic efficacy and safety of fulranumab in postherpetic neuralgia (PHN) and posttraumatic neuropathy (PTN) patients.

Methods:

Patients (18 to 80 y) with inadequately controlled moderate-to-severe pain received study medication (subcutaneous injection) every 4 weeks. PHN patients were randomized (3:2:2:3) to receive either placebo or one of 3 doses of fulranumab: 1 mg (1 mgQ4 wk), 3 mg (3 mgQ4 wk), or 10 mg (10 mgQ4 wk). PTN patients were randomized (1:1) to receive either placebo or fulranumab 10 mgQ4 wk.

Results:

The US Food and Drug Administration placed a clinical hold (December 23, 2010) on all trials of antinerve growth factor drugs, including fulranumab, due to identified risks of osteonecrosis or rapidly progressing osteoarthritis; therefore, only 49 (of 150 planned) PHN patients and 34 (of 50 planned) PTN patients completed the DB efficacy evaluation. There was no significant difference (P>0.05, fulranumab vs. placebo) for change in 7-day average of daily pain intensity scores from DB baseline to end of 12-week DB efficacy phase in PHN or PTN patients (primary endpoint). No significant difference was found with fulranumab versus placebo (P>0.05) in other efficacy measures in either PHN or PTN patients. The most common treatment-emergent adverse events (>10% incidence) in PTN patients were sinusitis, carpal tunnel syndrome, and headache, whereas in PHN patients it was arthralgia.

Discussion:

Fulranumab did not demonstrate efficacy in either PHN or PTN patients, but was generally well-tolerated in this small underpowered and abbreviated study.

Pain relief of sore throat with a new anti-inflammatory throat lozenge, ibuprofen 25 mg: A randomised, double-blind, placebo-controlled, international phase III study

OBJECTIVE

The aim of this study was to compare the efficacy and safety of a new oromucosal ibuprofen form, ibuprofen 25 mg lozenge, in single and repeat dosing for up to 4 days, to the matched placebo, in the treatment of acute sore throat pain in adults.

METHODS

In this randomised, double-blind, placebo-controlled trial, adult patients with non-streptococcal sore throat and signs of moderate-to-severe associated pain (≥5 on the objective Tonsillo-Pharyngitis Assessment 21-point scale and ≥60 mm on the subjective 0-100 mm visual analogue Sore Throat Pain Intensity Scale [STPIS]) were assigned ibuprofen 25 mg (n=194) or matching placebo (n=191) lozenge treatment. Efficacy was assessed (at the investigating centre up to 2 hours after first dosing, then on an ambulatory basis) by parameters derived from patient's scores on scales of pain relief, pain intensity, and global efficacy assessment. The primary efficacy end-point was the time-weighted TOTal PAin Relief (TOTPAR) over 2 hours after first dosing using the Sore Throat Relief Scale (STRS). Safety and local tolerability were assessed.

RESULTS

Ibuprofen 25 mg was superior to placebo on numerous pain relief parameters; TOTPAR was significantly higher with ibuprofen 25 mg over 2 hours after first dosing (P<.05), the effect being apparent from the first evaluation at 15 minutes (P<.05). The STPIS reduction in favour of ibuprofen 25 mg was not significant vs placebo. Mean STRS scores and patient's global efficacy assessment both reflected a higher efficacy of ibuprofen 25 mg over the 4-day treatment period with tests of statistical significance up to day 1 evening (P<.05), and, in patients with still clinically significant pain (n=128), after an average 4 days (P<.01). Ibuprofen 25 mg lozenge was well tolerated with a safety profile similar to placebo.

CONCLUSION

Low-dose ibuprofen 25 mg lozenge in repeat dosing provides in adults more efficacious and rapid relief of sore throat pain and is as well tolerated as placebo.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT01785862.

Breaking barriers to novel analgesic drug development

Acute and chronic pain complaints, although common, are generally poorly served by existing therapies. This unmet clinical need reflects a failure to develop novel classes of analgesics with superior efficacy, diminished adverse effects and a lower abuse liability than those currently available. Reasons for this include the heterogeneity of clinical pain conditions, the complexity and diversity of underlying pathophysiological mechanisms, and the unreliability of some preclinical pain models. However, recent advances in our understanding of the neurobiology of pain are beginning to offer opportunities for developing novel therapeutic strategies and revisiting existing targets, including modulating ion channels, enzymes and G-protein-coupled receptors.

Randomised, double-blind, parallel group, placebo-controlled study to evaluate the analgesic efficacy and safety of VVZ-149 injections for postoperative pain following laparoscopic colorectal surgery

INTRODUCTION

In spite of advances in understanding and technology, postoperative pain remains poorly treated for a significant number of patients. In colorectal surgery, the need for developing novel analgesics is especially important. Patients after bowel surgery are assessed for rapid return of bowel function and opioids worsen ileus, nausea and constipation. We describe a prospective, double-blind, parallel group, placebo-controlled randomised controlled trial testing the hypothesis that a novel analgesic drug, VVZ -149, is safe and effective in improving pain compared with providing opioid analgesia alone among adults undergoing laparoscopic colorectal surgery.

METHODS AND ANALYSIS

Based on sample size calculations for primary outcome, we plan to enrol 120 participants. Adult patients without significant medical comorbidities or ongoing opioid use and who are undergoing laparoscopic colorectal surgery will be enrolled. Participants are randomly assigned to receive either VVZ-149 with intravenous (IV) hydromorphone patient-controlled analgesia (PCA) or the control intervention (IV PCA alone) in the postoperative period. The primary outcome is the Sum of Pain Intensity Difference over 8 hours (SPID-8 postdose). Participants receive VVZ-149 for 8 hours postoperatively to the primary study end point, after which they continue to be assessed for up to 24 hours. We measure opioid consumption, record pain intensity and pain relief, and evaluate the number of rescue doses and requests for opioid. To assess safety, we record sedation, nausea and vomiting, respiratory depression, laboratory tests and ECG readings after study drug administration. We evaluate for possible confounders of analgesic response, such as anxiety, depression and catastrophising behaviours. The study will also collect blood sample data and evaluate for pharmacokinetic and pharmacodynamic relationships.

ETHICS AND DISSEMINATION

Ethical approval of the study protocol has been obtained from Institutional Review Boards at the participating institutions. Trial results will be disseminated through scientific conference presentations and by publication in scientific journals.

TRIAL REGISTRATION NUMBER

NCT02489526; pre-results.

Culturally Conscientious Pain Measurement in Older African Americans

Despite considerable pain disparities across the care continuum, pain is an understudied health problem in older ethnic minority groups, such as African Americans. Quality pain measurement is a core task in pain management and a mechanism by which pain disparities may be reduced. Pain measurement includes the methods (e.g., assessment approaches, tools) and metrics that researchers and clinicians use to understand the characteristics of pain. However, there are significant issues and gaps that negatively affect pain measurement in older African Americans. Of concern is insufficient representation in pain research, which impedes the testing and refinement of many standardized self-report, behavioral and surrogate report, physiological, and composite measures of pain. The purposes for this article are to discuss the status of pain measurement and factors that affect our knowledge on pain measurement in older African Americans, and to provide guidance for culturally conscientious pain measurement using the available literature.