Research design considerations for single-dose analgesic clinical trials in acute pain: IMMPACT recommendations

Desire to Receive More Pain Treatment - A Relevant Patient-Reported Outcome Measure to Assess Quality of Post-Operative Pain Management? Results From 79,996 Patients Enrolled in the Pain Registry QUIPS from 2016 to 2019

Acute postoperative pain is frequently evaluated by pain intensity scores. However, interpretation of the results is difficult and thresholds requiring treatment are not well defined. Additional patient-reported outcome measures (PROMs) might be helpful to better understand individual pain experience and quality of pain management after surgery. We used data from the QUIPS pain registry for a cross-sectional study in order to investigate associations between the desire to receive more pain treatment (D2RMPT) with pain intensity ratings and other PROMs. Responses from 79,996 patients were analyzed, of whom 10.7% reported D2RMPT. A generalized estimating equation Poisson model showed that women had a lower risk ratio (RR) to answer this question with "yes" (RR: .92, P < .001). Factors that increased the risk most were "maximal pain intensity ≥ 6/10 on a numerical rating scale" (RR: 2.48, P < .001) and "any pain interference" (RR: 2.48, P < .001). The largest reduction in risk was observed if patients were "allowed to participate in pain treatment decisions" (RR: .41, P < .001) and if they felt that they "received sufficient treatment information" (RR: .58, P < .001). Our results indicate that the (easily assessed) question D2RMPT gives additional information to other PROMs like pain intensity. The small proportion of patients with D2RMPT (even for high pain scores) opens the discussion about clinicians' understanding of over- und under-treatment and questions the exclusive use of pain intensity as quality indicator. Future studies need to investigate whether asking about D2RMPT in clinical routine can improve postoperative pain outcome. PERSPECTIVE: This article presents characteristics of the patient-reported outcome measure "Desire to receive more pain treatment." This measure could be used to apply pain treatment in a more individualized way and lead to improved treatment strategies and quality.

CYP450 polymorphisms and clinical pharmacogenetics of ibuprofen after lower third molar extraction

PURPOSE

This study hypothesized that drugs accumulate in the bloodstream of poor-metabolizing patients and may have more adverse effects and different pain perceptions and aimed to investigate the influence of CYP450 polymorphisms on acute postoperative pain, swelling, and trismus controlled by ibuprofen (600 mg) in 200 volunteers after dental extraction. In addition, surgical outcomes can determine pain, edema, and trismus and indicate inflammatory reactions after oral surgeries.

METHODS

Genetic sequencing was performed to identify CYP450 polymorphisms and the surgical parameters evaluated: pre and postoperative swelling, trismus, and temperature; self-reported postoperative pain with visual analog scale (VAS); rescue medication consumed; and severity of adverse reactions.

RESULTS

A multiple linear regression model with independent variables [single nucleotide polymorphisms (SNPs), BMI (body mass index), duration, and difficulty of surgery] and dependent variables [postoperative pain by sum of pain intensity difference (SPID), trismus, and swelling] was used for analysis. The duration of surgery was a predictor for pain at 8 h and 96 h after surgery, and BMI was a predictor for both swelling and trismus on the 2nd postoperative day. When evaluating CYP2C8 and C9 genotyped SNPs, it was observed that normal metabolizers showed higher pain levels than the intermediate/poor metabolizers on the postoperative periods as compared with time 0 h. In another analysis, the poor metabolizers for CYP2C8 and C9 presented lower levels of postoperative pain after 8 h and used rescue medication earlier than normal metabolizers.

CONCLUSION

Ibuprofen 600 mg was very effective in controlling inflammatory pain after lower third molar surgeries, without relevant adverse reactions; although in a very subtle way, patients with poor metabolism had higher levels of pain in the first hours, and no longer after 8 h, and used pain relief medication earlier.

TRIAL REGISTRATION

The study was registered with ClinicalTrials.gov ID (NCT03169127), on March 16th, 2017.

Efficacy of high-dissolution turmeric-sesame formulation for pain relief in adult subjects with acute musculoskeletal pain compared to acetaminophen: A randomized controlled study

BACKGROUND

Acetaminophen (paracetamol) is one of the most commonly used over-the-counter for pain relief. Management of acute pain with plant-based nutrients has remained suboptimal due to an absence of data supporting acute relief of pain. In the present study, it was hypothesized that high-dissolution liquid treatment of black sesame extract oil, Curcuma longa and Boswellia serrata may provide pain relief in people with acute musculoskeletal pain as quickly as acetaminophen.

METHODS

In this randomized active controlled open label study, 88 healthy subjects with acute musculoskeletal pain were randomized to receive treatment capsule (Rhuleave-K; 1,000 mg/d) or 1,000 mg/d acetaminophen for 7 days. Change in pain intensity and pain relief at first 6 hours, 3 days, and 7 days were measured. The onset of analgesia was measured by perceptible pain relief and meaningful pain relief. Other measures were McGill Pain Questionnaire and Patient Global Impression Change.

RESULTS

The treatment formulation resulted in average magnitude of pain relief comparable to the acetaminophen. Sixty-six percent of subjects in the treatment group reported positive response in pain relief (≥50% max TOTPAR; total pain relief) after 6 hours, compared to 73% of control. Seventy-three percent of subjects on treatment were considered positive responders, compared to 80% in the control group. The average time of onset of analgesia was 1 hour for the treatment group, versus 0.83 hour for control. At the end of day 3 and 7, there was significant improvement (P < .001 for day 3 and day 7) in the pain condition of treatment group and was comparable to control (P = .436 for day 3 and P = .529 for day 7). The total McGill Pain score showed significant reduction in pain with the treatment irrespective of the pain intensity statistically equal (P = .468) to control. Both the groups were equal in providing sensory pain relief (P = .942), but the treatment was 8.57 times significantly better (P = .027) than acetaminophen in reducing the unpleasantness and emotional aspects (affective domain) involved with acute pain.

CONCLUSION

The results showed that the treatment used in the study may act as a natural, fast acting, and safe alternative for acute pain relief comparable to acetaminophen.

Perioperative Use of Gabapentinoids for the Management of Postoperative Acute Pain

Background

Widely used for acute pain management, the clinical benefit from perioperative use of gabapentinoids is uncertain. The aim of this systematic review was to assess the analgesic effect and adverse events with the perioperative use of gabapentinoids in adult patients.

Methods

Randomized controlled trials studying the use of gabapentinoids in adult patients undergoing surgery were included. The primary outcome was the intensity of postoperative acute pain. Secondary outcomes included the intensity of postoperative subacute pain, incidence of postoperative chronic pain, cumulative opioid use, persistent opioid use, lengths of stay, and adverse events. The clinical significance of the summary estimates was assessed based on established thresholds for minimally important differences.

Results

In total, 281 trials (N = 24,682 participants) were included in this meta-analysis. Compared with controls, gabapentinoids were associated with a lower postoperative pain intensity (100-point scale) at 6 h (mean difference, −10; 95% CI, −12 to −9), 12 h (mean difference, −9; 95% CI, −10 to −7), 24 h (mean difference, −7; 95% CI, −8 to −6), and 48 h (mean difference, −3; 95% CI, −5 to −1). This effect was not clinically significant ranging below the minimally important difference (10 points out of 100) for each time point. These results were consistent regardless of the type of drug (gabapentin or pregabalin). No effect was observed on pain intensity at 72 h, subacute and chronic pain. The use of gabapentinoids was associated with a lower risk of postoperative nausea and vomiting but with more dizziness and visual disturbance.

Conclusions

No clinically significant analgesic effect for the perioperative use of gabapentinoids was observed. There was also no effect on the prevention of postoperative chronic pain and a greater risk of adverse events. These results do not support the routine use of pregabalin or gabapentin for the management of postoperative pain in adult patients.

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A Randomized, Double-Blind, Placebo-Controlled Trial of Ibuprofen Lysinate in Comparison to Ibuprofen Acid for Acute Postoperative Dental Pain

INTRODUCTION

Ibuprofen acid is poorly soluble in the stomach, thus reaching maximum plasma levels at approximately 90 min post-dose. Ibuprofen lysinate has been developed to accelerate absorption of ibuprofen to shorten the time to analgesic efficacy. This study compared analgesic efficacy and onset of effect of a single dose of ibuprofen lysinate or ibuprofen acid in patients undergoing third molar extraction.

METHODS

Randomized, double-blind, placebo-controlled, multi-center, parallel-group single-dose study. Adults (18-60 years) undergoing extraction of ≥ 1 third molar were randomized 2:2:1 to ibuprofen lysinate, ibuprofen acid, or placebo postoperatively. Pain relief (PAR, 5-point scale, 0 = none to 4 = complete pain relief) and pain intensity (PI, 100 mm visual analog scale) were assessed between 15 and 360 min post-dose. The primary endpoint was the weighted sum of PAR scores at 6 h (TOTPAR). Time to onset of effect, global assessment of efficacy, and adverse events were also assessed.

RESULTS

Overall, 351 patients received ibuprofen lysinate (N = 141), ibuprofen acid (N = 139), or placebo (N = 71). Both active treatments significantly reduced pain compared with placebo, from 15 min post-dose to 6 h (TOTPAR: ibuprofen lysinate: 19.57; ibuprofen acid: 19.96; placebo: 8.27). Ibuprofen lysinate was significantly more effective than placebo, but non-inferior to ibuprofen acid, at providing pain relief over 6 h. There was no significant difference between ibuprofen lysinate and ibuprofen acid for onset of analgesia. Both ibuprofen formulations were well tolerated; all adverse events were mild to moderate and considered unrelated to treatment.

CONCLUSIONS

A single dose of ibuprofen lysinate is non-inferior to ibuprofen acid in terms of analgesic efficacy, onset of action, and tolerability in patients who have recently undergone dental surgery.

TRIAL REGISTRATION

EudraCT No. 2006-006942-33. Plain language summary available for this article.

The Therapeutic Effectiveness of Full Spectrum Hemp Oil Using a Chronic Neuropathic Pain Model

BACKGROUND

Few models exist that can control for placebo and expectancy effects commonly observed in clinical trials measuring 'Cannabis' pharmacodynamics. We used the Foramen Rotundum Inflammatory Constriction Trigeminal Infraorbital Nerve injury (FRICT-ION) model to measure the effect of "full-spectrum" whole plant extracted hemp oil on chronic neuropathic pain sensitivity in mice.

METHODS

Male BALBc mice were submitted to the FRICT-ION chronic neuropathic pain model with oral insertion through an incision in the buccal/cheek crease of 3 mm of chromic gut suture (4-0). The suture, wedged along the V2 trigeminal nerve branch, creates a continuous irritation that develops into secondary mechanical hypersensitivity on the snout. Von Frey filament stimuli on the mouse whisker pad was used to assess the mechanical pain threshold from 0-6 h following dosing among animals (n = 6) exposed to 5 μL of whole plant extracted hemp oil combined with a peanut butter vehicle (0.138 mg/kg), the vehicle alone (n = 3) 7 weeks post-surgery, or a naïve control condition (n = 3).

RESULTS

Mechanical allodynia was alleviated within 1 h (d = 2.50, p < 0.001) with a peak reversal effect at 4 h (d = 7.21, p < 0.001) and remained significant throughout the 6 h observation window. There was no threshold change on contralateral whisker pad after hemp oil administration, demonstrating the localization of anesthetic response to affected areas.

CONCLUSION

Future research should focus on how whole plant extracted hemp oil affects multi-sensory and cognitive-attentional systems that process pain.

The pharmacological management of dental pain

Introduction: Dental pain is primarily treated by dentists and emergency medicine clinicians and may occur because of insult to the tooth or oral surgery. The dental impaction pain model (DIPM) has been widely used in clinical studies of analgesic agents and is generalizable to many other forms of pain.Areas Covered: The authors discuss the DIPM, which has allowed for important head-to-head studies of analgesic agents, such as acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and combinations. Postsurgical dental pain follows a predictable trajectory over the course of one to 3 days. Dental pain may have odontic origin or may be referred pain from other areas of the body.Expert opinion: Pain following oral surgery has sometimes been treated with longer-than-necessary courses of opioid therapy. Postsurgical dental pain may be moderate to severe but typically resolves in a day or two after the extraction. Opioid monotherapy, rarely used in dentistry but combination therapy (opioid plus acetaminophen or an NSAID), was sometimes used as well as nonopioid analgesic monotherapy. The dental impaction pain model has been valuable in the study of analgesics but does not address all painful conditions, for example, pain with a neuropathic component.

Longer analgesic effect with naproxen sodium than ibuprofen in post-surgical dental pain: a randomized, double-blind, placebo-controlled, single-dose trial

Background: Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended as first-line medications in mild-to-moderate acute pain. However, comparative data regarding the duration of analgesia for commonly-used NSAIDs at non-prescription doses is lacking. This study evaluated the time to rescue medication following a single dose of naproxen sodium (NAPSO) vs ibuprofen (IBU) and placebo in subjects with moderate-to-severe post-surgical dental pain.Methods: This single-center, randomized, double-blind, parallel group, placebo-controlled study included healthy subjects with moderate-to-severe baseline pain (Categorical Pain Intensity Scale) who also rated their pain ≥ 5 on a 0-10 pain intensity Numerical Rating Scale following extraction of two impacted mandibular third molars. A single oral dose of NAPSO (440 mg), IBU (400 mg), or placebo was administered. The primary efficacy endpoint was the time to first rescue medication, while secondary endpoints included the sum of pain intensity difference (SPID) and total pain relief (TOTPAR) over 24 h. ClinicalTrials.gov trial registration number: NCT03404206 (EudraCT 2017-005049-67).Results: In the per protocol population (n = 385; mean age = 19 years), the time to rescue medication was significantly (p < .001) longer with NAPSO than IBU and placebo. After treatment, the greatest separation of NAPSO from IBU occurred at 9-14 h and from placebo at 1-6 h. Fewer NAPSO subjects required rescue medication (58/166, 34.9%) compared with IBU (137/165, 83.0%) and placebo (44/54, 81.5%). SPID 0-24 h and TOTPAR 0-24 h were both greater with NAPSO than IBU or placebo.Conclusions: The duration of pain relief after a single dose of NAPSO was significantly longer than after IBU, and significantly fewer NAPSO-treated subjects required rescue medication over a 24-h period.

Relieving acute pain (RAP) study: a proof-of-concept protocol for a randomised, double-blind, placebo-controlled trial

INTRODUCTION

Physicians and other prescribing clinicians use opioids as the primary method of pain management after traumatic injury, despite growing recognition of the major risks associated with usage for chronic pain. Placebos given after repeated administration of active treatments can acquire medication-like effects based on learning mechanisms. This study hypothesises that dose-extending placebos can be an effective treatment in relieving clinical acute pain in trauma patients who take opioids.

METHODS AND ANALYSIS

The relieving acute pain is a proof-of-concept randomised, placebo-controlled, double-blinded, single-site study enrolling 159 participants aged from 18 to 65 years with one or more traumatic injuries treated with opioids. Participants will be randomly assigned to three different arms. Arm 1 will receive the full dose of opioids with non-steroidal anti-inflammatory drugs (NSAIDs). Arm 2 will receive the 50% overall reduction in opioid dosage, dose-extending placebos and NSAIDs. Arm 3 (control) will receive NSAIDs and placebos. The trial length will be 3 days of hospitalisation (phase I) and 2-week, 1-month, 3-month and 6-month follow-ups (exploratory phase II). Primary and secondary outcomes include feasibility and acceptability of the study. Pain intensity, functional pain, emotional distress, rates of rescue therapy requests and patient-initiated medication denials will be collected.

ETHICS AND DISSEMINATION

All activities associated with this protocol are conducted in full compliance with the Institutional Review Board policies and federal regulations. Publishing this study protocol will enable researchers and funding bodies to stay up to date in their fields by providing exposure to research activity that may not otherwise be widely publicised.

DATE AND PROTOCOL VERSION IDENTIFIER

3/6/2019 (HP-00078742).

TRIAL REGISTRATION NUMBER

NCT03426137.

A survey of postoperative pain treatments and unmet needs

More than 300 million patients undergo surgery worldwide each year. Pain associated with these procedures is associated with short- and long-term negative sequelae for patients, healthcare providers, and healthcare systems. The following chapter is a review of the reality of postoperative pain management in everyday clinical routine based on survey- and registry-derived data with a focus on care in adults. Between 30% and up to 80% of patients report moderate to severe pain in the days after surgery. Structures, processes, and outcomes vary widely between hospitals and indicate gaps between evidence-based findings and practice. Pain assessment is not effectively implemented in many hospitals and should consider cultural differences. Few data exist on the situation of pain management in low- and middle-income countries, indicating lack of resources and available medication in many of these areas. Certain types of surgery as well as demographic and clinical factors are associated with increased risk of severe postoperative pain.

Adductor canal blocks for postoperative pain treatment in adults undergoing knee surgery

BACKGROUND

Peripheral regional anaesthesia techniques are well established for postoperative pain treatment following knee surgery. The adductor canal block (ACB) is a new technique, which can be applied as a single shot or by catheter for continuous regional analgesia.

OBJECTIVES

To compare the analgesic efficacy and adverse events of ACB versus other regional analgesic techniques or systemic analgesic treatment for adults undergoing knee surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase, five other databases, and one trial register on 19 September 2018; we checked references, searched citations, and contacted study authors to identify additional studies.

SELECTION CRITERIA

We included all randomized controlled trials (RCTs) comparing single or continuous ACB versus other regional analgesic techniques or systemic analgesic treatment. Inclusion was independent of the technique used (landmarks, peripheral nerve stimulator, or ultrasound) and the level of training of providers.

DATA COLLECTION AND ANALYSIS

We used Cochrane's standard methodological procedures. Our primary outcomes were pain intensity at rest and during movement; rate of accidental falls; and rates of opioid-related adverse events. We used GRADE to assess the quality of evidence for primary outcomes.

MAIN RESULTS

We included 25 RCTs (1688 participants) in this review (23 trials combined within meta-analyses). In 18 studies, participants underwent total knee arthroplasty (TKA), whereas seven trials investigated patients undergoing arthroscopic knee surgery. We identified 11 studies awaiting classification and 11 ongoing studies. We investigated the following comparisons. ACB versus sham treatment We included eight trials for this comparison. We found no significant differences in postoperative pain intensity at rest (2 hours: standardized mean difference (SMD) -0.56, 95% confidence interval (CI) -1.20 to 0.07, 4 trials, 208 participants, low-quality evidence; 24 hours: SMD -0.49, 95% CI -1.05 to 0.07, 6 trials, 272 participants, low-quality evidence) or during movement (2 hours: SMD -0.59, 95% CI -1.5 to 0.33; 3 trials, 160 participants, very low-quality evidence; 24 hours: SMD 0.03, 95% CI -0.26 to 0.32, 4 trials, 184 participants, low-quality evidence). Furthermore, they noted no evidence of a difference in postoperative nausea between groups (24 hours: risk ratio (RR) 1.91, 95% CI 0.48 to 7.58, 3 trials, 121 participants, low-quality evidence). One trial reported that no accidental falls occurred 24 hours postoperatively (low-quality evidence). ACB versus femoral nerve block We included 15 RCTs for this comparison. We found no evidence of a difference in postoperative pain intensity at rest (2 hours: SMD -0.74, 95% CI -1.76 to 0.28, 5 trials, 298 participants, low-quality evidence; 24 hours: SMD 0.04, 95% CI -0.09 to 0.18, 12 trials, 868 participants, high-quality evidence) or during movement (2 hours: SMD -0.47, 95% CI -1.86 to 0.93, 2 trials, 88 participants, very low-quality evidence; 24 hours: SMD 0.56, 95% CI -0.00 to 1.12, 9 trials, 576 participants, very low-quality evidence). They noted no evidence of a difference in postoperative nausea (24 hours: RR 1.22, 95% CI 0.42 to 3.54, 2 trials, 138 participants, low-quality evidence) and no evidence that the rate of accidental falls during postoperative care was significantly different between groups (24 hours: RR 0.20, 95% CI 0.04 to 1.15, 3 trials, 172 participants, low-quality evidence).

AUTHORS' CONCLUSIONS

We are currently uncertain whether patients treated with ACB suffer from lower pain intensity at rest and during movement, fewer opioid-related adverse events, and fewer accidental falls during postoperative care compared to patients receiving sham treatment. The same holds true for the comparison of ACB versus femoral nerve block focusing on postoperative pain intensity. The overall evidence level was mostly low or very low, so further research might change the conclusion. The 11 studies awaiting classification and the 11 ongoing studies, once assessed, may alter the conclusions of this review.

Efficacy and Safety of Intravenous Meloxicam in Patients With Moderate-to-Severe Pain Following Bunionectomy: A Randomized, Double-Blind, Placebo-controlled Trial

OBJECTIVE

To evaluate the analgesic efficacy and safety of a novel intravenous (IV) formulation of meloxicam (30 mg) in patients with moderate-to-severe pain following a standardized, unilateral bunionectomy with first metatarsal osteotomy and internal fixation.

MATERIALS AND METHODS

Patients who met the criteria for moderate-to-severe postoperative pain were randomized to receive bolus injections of meloxicam IV 30 mg (n=100) or placebo (n=101) administered once daily. The primary efficacy endpoint was the Summed Pain Intensity Difference over 48 hours (SPID48). Secondary efficacy endpoints included sum of time-weighted pain intensity differences (SPID) values at other timepoints/intervals, time to first use of rescue analgesia, and number of rescue doses taken. Safety assessments included the incidence of adverse events (AEs), physical examinations, laboratory tests, 12-lead electrocardiography, and wound healing.

RESULTS

Patients randomized to meloxicam IV 30 mg exhibited a statistically significant difference in SPID48 versus the placebo group (P=0.0034). Statistically significant differences favoring meloxicam IV over placebo were also observed for secondary efficacy endpoints, including SPID at other times/intervals (SPID6: P=0.0153; SPID12: P=0.0053; SPID24: P=0.0084; and SPID24-48: P=0.0050) and first use of rescue medication (P=0.0076). Safety findings indicated that meloxicam IV 30 mg was generally well tolerated; no serious AEs or bleeding events were observed. Most AEs were assessed by the investigator to be mild in intensity, and no patients discontinued due to AEs. There were no meaningful differences between the study groups in vital signs, electrocardiographic findings, or laboratory assessments. In most cases, investigators found that wound healing followed a normal course and mean wound-healing satisfaction scores were similar for meloxicam IV 30 mg and placebo.

DISCUSSION

Meloxicam IV doses of 30 mg provided effective pain relief when administered once daily by bolus injection to patients with moderate-to-severe pain following bunionectomy, and had an acceptable safety profile.

Current Status and Future Directions of Pain-Related Outcome Measures for Post-Surgical Pain Trials

Background: Clinical trials remain vital in order to: A) develop new treatment interventions, and also, B) to guide optimal use of current interventions for the treatment and prevention of acute and chronic postsurgical pain. Measures of pain (e.g. intensity and relief) and opioid use have been validated for the settings of postsurgical pain and continue to effectively guide research in this field..

Methods: This narrative review considers needs for innovation in postsurgical pain trial outcomes assessment.

Results: Future improvements are needed and include: A) more widespread measurement of movement-evoked pain with validation of various procedure-relevant movemen-tevoked pain maneuvers; B) new validated analytical approaches to integrate early postoperative pain scores with opioid use; and, C) closer attention to the measurement of postoperative opioid use after hospital discharge. In addition to these traditional measures, consideration is being given to the use of new pain-relevant outcome domains that include: 1) other symptoms (e.g. nausea and vomiting), 2) recovery of physiological function (e.g. respiratory, gastrointestinal, genitourinary and musculoskeletal), 3) emotional function (e.g. depression, anxiety) and, 4) development of chronic postsurgical pain. Also, there is a need to develop pain-related domains and measures for evaluating both acute and chronic post-operative pain. Finally, evidence suggests that further needs for improvements in safety assessment and reporting in postsurgical pain trials is needed, e.g. by using an agreed upon, standardized collection of outcomes that will be reported as a minimum in all postsurgical pain trials.

Conclusions: These proposed advances in outcome measurement methodology are expected to improve the success by which postsurgical pain trials guide improvements in clinical care and patient outcomes.

Ibuprofen and Acetaminophen Versus Intranasal Ketorolac (Sprix) in an Untreated Endodontic Pain Model: A Randomized, Double-blind Investigation

INTRODUCTION

Previously, ketorolac was available for primary use only via intravenous and intramuscular routes. Its availability in intranasal form offers an alternative route of administration that patients can self-administer. The purpose of this study was to compare the efficacy of intranasal ketorolac (Sprix; Egalet US Inc, Wayne, PA) with a combination of ibuprofen/acetaminophen in an acute pain model of untreated endodontic patients experiencing moderate to severe pain and symptomatic apical periodontitis.

METHODS

Seventy patients experiencing moderate to severe pain, a pulpal diagnosis of symptomatic irreversible pulpitis or necrosis, and a periapical diagnosis of symptomatic apical periodontitis participated. Patients were randomly divided into 2 groups and received either 31.5 mg intranasal ketorolac and placebo capsules or 1000 mg acetaminophen/600 mg ibuprofen capsules and a mock nasal spray. Patients recorded perceived pain scores on a visual analog scale every 15 minutes from drug administration up to 240 minutes. The time to 50% pain relief, the first sign of pain relief, and meaningful pain relief were recorded, and the data were analyzed.

RESULTS

A decline in reported pain was observed until 120 minutes after dosing, after which reported pain remained relatively constant. There was no significant difference between the 2 groups for the time to 50% pain relief, the first sign of pain relief, or meaningful pain relief.

CONCLUSIONS

The effectiveness of intranasal ketorolac was not significantly different from that of a 1000 mg acetaminophen/600 mg ibuprofen combination. Intranasal ketorolac provides a nonnarcotic alternative and an additional route of medication administration to practicing clinicians.

Analgesic Efficacy and Safety of Intravenous Meloxicam in Subjects With Moderate-to-Severe Pain After Open Abdominal Hysterectomy: A Phase 2 Randomized Clinical Trial

BACKGROUND

An intravenous (IV) formulation of meloxicam was developed for moderate-to-severe pain management. This study evaluated the safety and efficacy of meloxicam IV after open abdominal hysterectomy. Meloxicam IV is an investigational product not yet approved by the US Food and Drug Administration.

METHODS

Women (N = 486) with moderate-to-severe pain after open abdominal hysterectomy were enrolled in this multicenter, randomized, double-blind, placebo- and active-controlled trial. Subjects were randomized to receive a single dose of meloxicam IV (5-60 mg), placebo, or morphine (0.15 mg/kg) in ≤6 hours after morphine dosing on postoperative day 1 and were evaluated for 24 hours. Rescue morphine (≈0.15 mg/kg IV) was available if needed for pain not relieved by the study medication. In an open-label extension (N = 295), meloxicam IV was administered once daily for the remaining hospital stay (or per the investigator's discretion). The coprimary efficacy end points were the summed pain intensity difference (SPID24) and total pain relief (TOTPAR24) from hour 0 to 24 hours after dosing. Effect size, the standardized difference between means reported in standard deviation (SD) units, was calculated to indicate the magnitude of the difference in the mean analgesic effect measured for different intervention groups.

RESULTS

Subjects who received morphine or meloxicam IV had a median time to first perceptible pain relief within 6-8 minutes. Morphine and meloxicam IV 5-60 mg produced statistically significant differences than placebo in SPID24 and TOTPAR24. SPID24 (standard error [SE]) for meloxicam IV 5-60 mg ranged from -56276.8 (3926.46) to -33517.1 (3930.1; P < .001); SPID24 (SE) for morphine and placebo were -29615.8 (3869.2; P < .001) and 4555.9 (3807.1), respectively. SPID24 effect sizes (95% confidence intervals) for the 60, 30, 15, 7.5, and 5 mg meloxicam IV doses and morphine were 1.93 (1.61-2.25), 2.00 (1.65-2.35), 1.70 (1.35-2.05), 1.28 (0.95-1.60), 1.25 (0.90-1.61), and 1.12 (0.77-1.45) SDs, respectively. TOTPAR24 (SE) for meloxicam IV 5-60 mg ranged from 3104.5 (155.28) to 4130.4 (191.17; P < .001); TOTPAR24 (SE) for morphine and placebo were 2723.3 (188.4; P < .001) and 1100.6 (185.4), respectively. TOTPAR24 effect sizes (95% confidence interval) for the 60, 30, 15, 7.5, and 5 mg meloxicam IV doses and morphine were 2.03 (1.70-2.35), 2.05 (1.70-2.40), 1.78 (1.43-2.13), 1.35 (1.03-1.67), 1.37 (1.01-1.72), and 1.10 (0.75-1.45) SDs, respectively. The mean total opioid consumed (SD) during the double-blind phase was 4.6 (8.17), 5.3 (8.85), 5.9 (7.85), 8.5 (9.67), 9.3 (9.47), 9.6 (8.12), and 16.0 (10.15) mg for patients in the 60, 30, 15, 7.5, and 5 mg meloxicam IV, morphine, and placebo groups, respectively. Generally, meloxicam IV was well tolerated, evidenced by the incidence of adverse events compared to placebo and lack of deaths and treatment-related serious adverse events.

CONCLUSIONS

A meloxicam IV dose of 5-60 mg was generally well tolerated and appeared to reduce opioid consumption in subjects with moderate-to-severe pain after open abdominal hysterectomy. Once-daily administration of meloxicam IV produced analgesic effect within 6-8 minutes postdose that was maintained over a 24-hour dosing interval.

Opportunities and challenges for junior investigators conducting pain clinical trials

Introduction

Clinical investigation serves a vital role to advance treatment and management stratgies for patients with pain. For those new to clinical investigation, key advice for both the novice clinical-investigator and the experienced researcher expanding to translational work may accelerate research efforts.

Objective

To review foundational material relevant to junior investigators focusing on pain clinical trials, with an emphasis on randomized controlled trials.

Methods

We reviewed recent publications and resources relevant to clinical investigators, with a particular emphasis on pain research.

Results

Understanding the approaches and barriers to clinical pain research is a first step to building a successful investigative portfolio. Key components of professional development include motivation, mentorship, and collaborative approaches to research. Many junior clinical-investigators face challenges in pursing research careers and sparking iterative progress towards success in clinical trials. Pain-specific research metrics and goals-including hypothesis development, study design considerations, and regulatory concerns-are also important considerations to junior investigators who pursue clinical trails. Approaches to build toward collaborative and independent funding are essential for investigators.

Conclusions

This work provides a foundation for understanding the clinical research process and helps inform the goals and plans of clinical-investigators.

Tramadol/dexketoprofen (TRAM/DKP) compared with tramadol/paracetamol in moderate to severe acute pain: results of a randomised, double-blind, placebo and active-controlled, parallel group trial in the impacted third molar extraction pain model (DAVID study)

OBJECTIVES

To compare efficacy/safety of oral tramadol 75 mg/dexketoprofen 25 mg (TRAM/DKP) and TRAM 75 mg/paracetamol 650 mg (TRAM/paracetamol) in moderate to severe pain following surgical removal of impacted lower third molar.

DESIGN

Multicentre, randomised, double-blind, placebo-controlled, phase IIIb study.

PARTICIPANTS

Healthy adult patients scheduled for surgical extraction of at least one fully/partially impacted lower third molar requiring bone manipulation. 654 patients were randomised and 653 were eligible for analysis.

INTERVENTIONS

Surgery was performed under local anaesthetic. No sedation was permitted. Patients rated pain intensity (PI) using an 11-Numerical Rating Scale (NRS) (0 no pain; 10 worst pain). Participants experiencing moderate/severe pain (≥4) within 4 hours of surgery were randomised (2:2:1 ratio) to a single oral dose of TRAM/DKP 75/25 mg, TRAM/paracetamol 75/650 mg or placebo.

MAIN OUTCOME MEASURES

Efficacy was based patients' electronic diaries. Analgesia and pain were recorded as follows: pain relief (PAR) on a 5-point Verbal Rating Scale (0='no relief', 1='a little (perceptible) relief', 2='some (meaningful) relief', 3='lot of relief', 4='complete relief') at the predefined postdose time points t15 min, t30 min, t1 hour, t1.5 hour, t2 hour, t4 hour, t6 hour and t8 hour and PI on the 11-point NRS at t0 and at the same predefined postdose time points. Onset of analgesia documented using double stopwatch method over a 2-hour period. Primary endpoint was total pain relief over 6 hours (TOTPAR6). Rescue medication was available during the treatment period.

RESULTS

TRAM/DKP was superior to TRAM/paracetamol and placebo at the primary endpoint TOTPAR6 (p<0.0001). Mean (SD) TOTPAR6 in the TRAM/DKP group was 13 (6.97), while those in the active control and placebo groups were 9.2 (7.65) and 1.9 (3.89), respectively. Superiority of TRAM/DKP over active comparator and placebo was observed at all secondary endpoints. Incidence of adverse events was comparable between active groups.

CONCLUSIONS

TRAM/DKP (75/25 mg) is effective and superior to TRAM/paracetamol (75/650 mg) in relieving moderate to severe acute pain following surgical removal of impacted lower third molar, with a faster onset of action, greater and durable analgesia, together with a favourable safety profile.

TRIAL REGISTRATION NUMBER

EudraCT 2015-004152-22 and NCT02777970.

Improving perioperative pain management: a preintervention and postintervention study in 7 developing countries

Supplemental Digital Content is Available in the Text.

Introduction:

The burden of untreated postoperative pain is high.

Objective:

This study assessed feasibility of using quality improvement (QI) tools to improve management of perioperative pain in hospitals in multiple developing countries.

Methods:

The International Pain Registry and Developing Countries working groups, from the International Association for the Study of Pain (IASP), sponsored the project and PAIN OUT, a QI and research network, coordinated it, and provided the research tools. The IASP published a call about the project on its website. Principal investigators (PIs) were responsible for implementing a preintervention and postintervention study in 1 to 2 surgical wards in their hospitals, and they were free to choose the QI intervention. Trained surveyors used standardized and validated web-based tools for collecting findings about perioperative pain management and patient reported outcomes (PROs). Four processes and PROs, independent of surgery type, assessed effectiveness of the interventions.

Results:

Forty-three providers responded to the call; 13 applications were selected; and PIs from 8 hospitals, in 14 wards, in 7 countries, completed the study. Interventions focused on teaching providers about pain management. Processes improved in 35% and PROs in 37.5% of wards.

Conclusions:

The project proved useful on multiple levels. It offered PIs a framework and tools to perform QI work and findings to present to colleagues and administration. Management practices and PROs improved on some wards. Interpretation of change proved complex, site-dependent, and related to multiple factors. PAIN OUT gained experience coordinating a multicentre, international QI project. The IASP promoted research, education, and QI work.

A Proof-of-concept Study Using Quantitative Sensory Threshold Analysis to Compare Two Intraoral Topical Anesthetics

PURPOSE

CTY-5339A is an investigational topical anesthetic spray containing 14% benzocaine/2% tetracaine in a metered canister. Each spray delivers ∼0.2 mL of solution. This double-blind, randomized, crossover study compared the local anesthetic effect of CTY-5339A versus 14% benzocaine alone by using 2 quantitative sensory threshold experimental pain paradigms on the maxillary gingiva: pin prick test pain intensity (PPT PI) and heat pain threshold (HPT).

METHODS

American Society of Anesthesiology Class 1 and 2 subjects (N = 50) were enrolled in this study. To qualify for the study, subjects were tested on the anterior maxillary gingiva with both PPT and HPT. Subjects had to report a PPT PI of ≥3 on a 0 to 10 numeric pain intensity scale on 1 of 2 consecutive pin pricks separated by 10 s, with at least one score ≥4. After PPT, mean HPT following 2 ramps in the same location had to be ≤ 46.5 °C, with each ramp beginning at 35 °C and an automatic cutoff of 50.6 °C. For treatment visits, subjects were randomly administered either 1 spray of CTY-5339A or 14% benzocaine to the anterior maxillary gingiva within 3 weeks of screening and then the alternative treatment 5 days to 2 weeks later. PPT PI and HPT were recorded immediately before drug application. After drug administration, PPT PI was recorded every minute through 5 min. Commencing at 5 min, PPT PI and HPT were recorded every 5 min through 60 min. For assessment of methemoglobin concentrations, venous blood (5 mL) was drawn from the antecubital fossa both before and 60 min after drug application. Oxygen saturation was recorded via pulse oximetry at baseline and every 10 min.

FINDINGS

The AUCs for pain intensity difference from 0-30 and 0-60 min after PPT and HPT differences were significantly greater (P < 0.0001) for CTY-5339A compared with 14% benzocaine. Multiple time points on the time-action curves for PPT PI difference and HPT difference statistically (P < 0.05) favored CTY-5399A. Methemoglobin and oxygen saturation levels did not change compared with baseline after dosing with either treatment.

IMPLICATIONS

Recommended doses of CTY-5339A provided significantly more profound and sustained local anesthesia than 14% benzocaine when applied to the maxillary gingiva. Significant changes in methemoglobin or oxygen saturation concentrations did not occur for either drug. ClinicalTrials.gov identifier: NCT03233737.

Anchoring the Numeric Pain Scale Changes Pain Intensity Reports in Patients With Chronic But Not With Acute Pain

BACKGROUND

Despite enormous differences between acute and chronic pain, the numeric pain scale (NRS) is commonly used in pain research and clinical practice for assessing the intensity of both acute and chronic pain. The use of this scale has been challenged as it may fail to accurately reflect the pure intensity of chronic pain.

AIM

To compare the effect of anchoring the NRS on the intensity of pain reported by patients with acute vs. chronic pain.

METHODS

Patients with acute postoperative or chronic pain (n = 100/group) were requested to rate their: current clinical pain intensity on an NRS from 0 to 100; the intensity of an anchoring pain event on the same scale; and subsequently to rate again their current pain intensity while making reference to the reported intensity of the pain event. The magnitude of correction was compared between the 2 groups.

RESULTS

The anchoring pain was rated identically between the groups. However, following anchoring, patients with chronic pain made a significantly larger correction of their pain intensity than did those with acute pain (mean ± standard deviation = 9 ± 9, median [interquartile range] = 10 [0 to 10] vs. 3 ± 7, 0 [0 to 5], respectively; P < 0.0001). More patients in the chronic pain group corrected their pain intensity. Logistic regression showed that chronic pain and female gender significantly increased the likelihood of making the correction (chronic pain: odds ratio 7.2, 95% confidence interval 3.5 to 15.1, P < 0.0001; female gender: odds ratio 2.8, 95% confidence interval 1.4 to 5.5, P < 0.0001).

CONCLUSION

The results suggest that anchoring the NRS can potentially improve the accuracy of reported chronic pain intensity.

Availability of researcher-led eHealth tools for pain assessment and management: barriers, facilitators, costs, and design

INTRODUCTION

Numerous eHealth tools for pain assessment and management have been developed and evaluated with promising results regarding psychometric properties, efficacy, and effectiveness. Although considerable resources are spent on developing and evaluating these tools with the aim of increasing access to care, current evidence suggests they are not made available to end users, reducing their impact and creating potential research waste.

METHODS

This study consisted of 2 components: (1) a systematic review of eHealth tools for pediatric pain assessment and/or management published in the past 10 years, and (2) an online survey, completed by the authors of identified tools, of tool availability, perceived barriers or facilitators to availability, grant funding used, and a validated measure of user-centeredness of the design process (UCD-11).

RESULTS

Ninety articles (0.86% of citations screened) describing 53 tools met inclusion criteria. Twenty-six survey responses were completed (49.06%), 13 of which (50.00%) described available tools. Commonly endorsed facilitators of tool availability included researchers' beliefs in tool benefits to the target population and research community; barriers included lack of infrastructure and time. The average cost of each unavailable tool was $314,425.31 USD ($3,144,253.06 USD total, n = 10). Authors of available tools were more likely to have followed user-centered design principles and reported higher total funding.

CONCLUSION

Systemic changes to academic and funding structures could better support eHealth tool availability and may reduce potential for research waste. User-centered design and implementation science methods could improve the availability of eHealth tools and should be further explored in future studies.

Content validation of a Critical Appraisal Tool for Reviewing Analgesia Studies (CATRAS) involving subjects incapable of self-reporting pain

INTRODUCTION

This article reports the content validation of a Critical Appraisal Tool designed to Review the quality of Analgesia Studies (CATRAS) involving subjects incapable of self-reporting pain and provide guidance as to the strengths and weakness of findings. The CATRAS quality items encompass 3 domains: level of evidence, methodological soundness, and grading of the pain assessment tool.

OBJECTIVES

To validate a critical appraisal tool for reviewing analgesia studies involving subjects incapable of self-reporting pain.

METHODS

Content validation was achieved using Delphi methodology through panel consensus. A panel of 6 experts reviewed the CATRAS in 3 rounds and quantitatively rated the relevance of the instrument and each of its quality items to their respective domains.

RESULTS

Content validation was achieved for each item of the CATRAS and the tool as a whole. Item-level content validity index and kappa coefficient were at least greater than 0.83 and 0.81, respectively, for all items except for one item in domain 2 that was later removed. Scale-level content validity index was 97% (excellent content validity).

CONCLUSIONS

This 67-item critical appraisal tool may enable critical and quantitative assessment of the quality of individual analgesia trials involving subjects incapable of self-reporting pain for use in systematic reviews and meta-analysis studies.

Randomized open-label [corrected] non-inferiority trial of acetaminophen or loxoprofen for patients with acute low back pain

BACKGROUND

Current worldwide clinical practice guidelines recommend acetaminophen as the first option for the treatment of acute low back pain. However, there is no concrete evidence regarding whether acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) is more effective for treating acute low back pain (LBP) in Japan. The present study aimed to investigate whether acetaminophen treatment for acute musculoskeletal pain was comparable with loxoprofen (a traditional NSAID in Japan) treatment.

METHODS

Of the 140 patients with acute LBP who visited out-patient hospitals, 127 were considered eligible and were randomly allocated to a group taking acetaminophen or one taking loxoprofen. As primary outcome measure, pain intensity was measured using a 0-10-numeric rating scale (NRS). Moreover, pain disability, pain catastrophizing, anxiety, depression, and quality of life, as well as adverse events, were assessed as secondary outcomes. The primary outcome was tested with a noninferiority margin (0.84 on changes in pain-NRS), and the secondary outcomes were compared using conventional statistical methods at week 2 and week 4.

RESULTS

Seventy patients completed the study (acetaminophen: 35, loxoprofen: 35). The dropout rates showed no significant difference between the two medication-groups. We found that the mean differences of changes in pain-NRS from baseline to week 2 or 4 between the two medication groups were not statistically beyond the noninferiority margin (mean [95% confidence interval]: -0.51 [-1.70, 0.67], at week 2 and -0.80 [-2.08, 0.48] at week 4). There were no consistent differences between the two medication groups in terms of secondary outcomes.

CONCLUSIONS

The results suggest that acetaminophen has comparable analgesic effects on acute LBP, based on at least a noninferiority margin, compared with loxoprofen at 4 weeks. Acetaminophen seems to be a reasonable first-line option for patients with acute LBP in Japan.

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.

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

Objective

With the increasing societal awareness of the prevalence and impact of acute pain, there is a need to develop an acute pain classification system that both reflects contemporary mechanistic insights and helps guide future research and treatment. Existing classifications of acute pain conditions are limiting, with a predominant focus on the sensory experience (e.g., pain intensity) and pharmacologic consumption. Consequently, there is a need to more broadly characterize and classify the multidimensional experience of acute pain.

Setting

Consensus report following 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).

Methods

As a complement to a taxonomy recently developed for chronic pain, the ACTTION public-private partnership with the US Food and Drug Administration, the APS, and the AAPM convened a consensus meeting of experts to develop an acute pain taxonomy using prevailing evidence. Key issues pertaining to the distinct nature of acute pain are presented followed by the agreed-upon taxonomy. The ACTTION-APS-AAPM Acute Pain Taxonomy will include the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms. Future efforts will consist of working groups utilizing this taxonomy to develop diagnostic criteria for a comprehensive set of acute pain conditions.

Perspective

The ACTTION-APS-AAPM Acute Pain Taxonomy (AAAPT) is a multidimensional acute pain classification system designed to classify acute pain along the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms.

Conclusions

Significant numbers of patients still suffer from significant acute pain, despite the advent of modern multimodal analgesic strategies. Mismanaged acute pain has a broad societal impact as significant numbers of patients may progress to suffer from chronic pain. An acute pain taxonomy provides a much-needed standardization of clinical diagnostic criteria, which benefits clinical care, research, education, and public policy. For the purposes of the present taxonomy, acute pain is considered to last up to seven days, with prolongation to 30 days being common. The current understanding of acute pain mechanisms poorly differentiates between acute and chronic pain and is often insufficient to distinguish among many types of acute pain conditions. Given the usefulness of the AAPT multidimensional framework, the AAAPT undertook a similar approach to organizing various acute pain conditions.

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

OBJECTIVE

With the increasing societal awareness of the prevalence and impact of acute pain, there is a need to develop an acute pain classification system that both reflects contemporary mechanistic insights and helps guide future research and treatment. Existing classifications of acute pain conditions are limiting, with a predominant focus on the sensory experience (eg, pain intensity) and pharmacologic consumption. Consequently, there is a need to more broadly characterize and classify the multidimensional experience of acute pain.

SETTING

Consensus report following 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).

METHODS

As a complement to a taxonomy recently developed for chronic pain, the ACTTION public-private partnership with the US Food and Drug Administration, the APS, and the AAPM convened a consensus meeting of experts to develop an acute pain taxonomy using prevailing evidence. Key issues pertaining to the distinct nature of acute pain are presented followed by the agreed-upon taxonomy. The ACTTION-APS-AAPM Acute Pain Taxonomy will include the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms. Future efforts will consist of working groups utilizing this taxonomy to develop diagnostic criteria for a comprehensive set of acute pain conditions.

PERSPECTIVE

The ACTTION-APS-AAPM Acute Pain Taxonomy (AAAPT) is a multidimensional acute pain classification system designed to classify acute pain along the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms.

CONCLUSIONS

Significant numbers of patients still suffer from significant acute pain, despite the advent of modern multimodal analgesic strategies. Mismanaged acute pain has a broad societal impact as significant numbers of patients may progress to suffer from chronic pain. An acute pain taxonomy provides a much-needed standardization of clinical diagnostic criteria, which benefits clinical care, research, education, and public policy. For the purposes of the present taxonomy, acute pain is considered to last up to seven days, with prolongation to 30 days being common. The current understanding of acute pain mechanisms poorly differentiates between acute and chronic pain and is often insufficient to distinguish among many types of acute pain conditions. Given the usefulness of the AAPT multidimensional framework, the AAAPT undertook a similar approach to organizing various acute pain conditions.

Evaluation of the safety and efficacy of an intravenous nanocrystal formulation of meloxicam in the management of moderate-to-severe pain after bunionectomy

Objective

This randomized, double-blind, placebo-controlled study evaluated the safety and efficacy of an intravenous (IV) nanocrystal formulation of meloxicam in subjects with moderate-to-severe pain following a standardized unilateral bunionectomy.

Methods

Fifty-nine subjects aged 18–72 years were randomized to receive doses of either 30 mg (n=20) or 60 mg (n=20) meloxicam IV or placebo (n=19), administered once daily as bolus IV injections over 15–30 seconds (two or three doses). Safety, the primary objective, was assessed by physical examination, clinical laboratory tests, and the incidence of adverse events (AEs). Efficacy was evaluated by examining summed pain intensity differences over the first 48 hours (SPID₄₈) using analysis of covariance models. Use of opioid rescue analgesic agents was evaluated.

Results

Generally, AEs were mild-to-moderate in intensity, and their incidence was similar across the three treatment groups. No serious AEs were reported; there were no withdrawals due to AEs, including injection-related AEs. The estimated effect size for SPID₄₈ versus placebo was 1.15 and 1.01 for meloxicam IV doses 30 mg and 60 mg, respectively (P≤0.01). Both doses produced significantly greater pain reductions versus placebo (P≤0.05) at all evaluated times/ intervals during the 48-hour period. The proportions of subjects with ≥30% and ≥50% overall reduction in pain from baseline after 6 and 24 hours were significantly higher with meloxicam IV 30 mg doses versus placebo, but not with meloxicam IV 60 mg doses. The time to first use of rescue medication was significantly longer versus placebo with meloxicam IV 60 mg (P<0.05), but not with meloxicam IV 30 mg doses.

Conclusion

Meloxicam IV was generally safe and well tolerated in subjects with moderate-to-severe post-bunionectomy pain. Once-daily administration of meloxicam IV 30 mg and 60 mg exhibited rapid onset of analgesia (as early as 15 minutes) with maintenance of analgesic effect for two consecutive 24-hour periods.

Clinical trial designs and models for analgesic medications for acute pain in neonates, infants, toddlers, children, and adolescents: ACTTION recommendations

Clinical trials to test the safety and efficacy of analgesics across all pediatric age cohorts are needed to avoid inappropriate extrapolation of adult data to children. However, the selection of acute pain models and trial design attributes to maximize assay sensitivity, by pediatric age cohort, remains problematic. Acute pain models used for drug treatment trials in adults are not directly applicable to the pediatric age cohorts-neonates, infants, toddlers, children, and adolescents. Developmental maturation of metabolic enzymes in infants and children must be taken into consideration when designing trials to test analgesic treatments for acute pain. Assessment tools based on the levels of cognitive maturation and behavioral repertoire must be selected as outcome measures. Models and designs of clinical trials of analgesic medications used in the treatment of acute pain in neonates, infants, toddlers, children, and adolescents were reviewed and discussed at an Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) Pediatric Pain Research Consortium consensus meeting. Based on extensive reviews and continuing discussions, the authors recommend a number of acute pain clinical trial models and design attributes that have the potential to improve the study of analgesic medications in pediatric populations. Recommendations are also provided regarding additional research needed to support the use of other acute pain models across pediatric age cohorts.

A Randomized Double-Blind Controlled Trial of Intravenous Meloxicam in the Treatment of Pain Following Dental Impaction Surgery

This randomized, controlled phase 2 study was conducted to evaluate the analgesic efficacy, safety, and tolerability of single intravenous (IV) doses of 15 mg, 30 mg, and 60 mg meloxicam compared with oral ibuprofen 400 mg and placebo after dental impaction surgery. The primary efficacy end point was the sum of time‐weighted pain intensity differences for 0‐24 hours postdose. Among 230 evaluable subjects, meloxicam IV 60 mg produced the greatest reduction in pain, followed by the 30‐mg and 15‐mg doses. Statistically significant differences in summed pain intensity differences over 24 hours were demonstrated for each active‐treatment group vs placebo (favoring active treatment) and for meloxicam IV 30 mg and 60 mg vs ibuprofen 400 mg (favoring meloxicam IV). Moreover, there was a statistically significant dose response for meloxicam IV 15 mg to 60 mg. The onset of action for meloxicam IV was rapid and sustained; significant differences in pain intensity differences were detected as early as 10 minutes postdose and lasted through the 24‐hour postdose period. Subjects in the meloxicam IV groups were more likely than placebo recipients to achieve perceptible and meaningful pain relief and were less likely to use rescue medication. Patient‐reported global evaluation showed that meloxicam IV 60 mg had the highest rating. There were no deaths, serious adverse events, or discontinuations due to adverse events. The incidence of subjects with ≥1 treatment‐emergent adverse event was greatest in the placebo group, followed by the groups that received ibuprofen, meloxicam IV 15 mg, 30 mg, and 60 mg. Nausea was the most commonly reported treatment‐emergent adverse event. Clinical trial registration number: NCT00945763.

A Systematic Review and Meta-analysis Comparing the Efficacy of Nonsteroidal Anti-inflammatory Drugs, Opioids, and Paracetamol in the Treatment of Acute Renal Colic

CONTEXT

Renal colic is a common, acute presentation of urolithiasis that requires immediate pain relief. European Association of Urology guidelines recommend nonsteroidal anti-inflammatory drugs (NSAIDs) as the preferred analgesia. However, the fear of NSAID adverse effects and the uncertainty about superior analgesic effect have maintained the practice of advocating intravenous opioids as the initial analgesia.

OBJECTIVE

The objective of this systematic review and meta-analysis was to compare the safety and efficacy of NSAIDs with opioids and paracetamol (acetaminophen) for the management of acute renal colic.

EVIDENCE ACQUISITION

Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, World Health Organization International Clinical Trials Registry Platform, Google Scholar, and the reference list of retrieved articles were searched up to December 2016 without language restrictions. Two reviewers independently assessed eligible studies using the Cochrane Collaboration tool for assessing and reporting the risk of bias and abstracted data using predefined data fields.

EVIDENCE SYNTHESIS

From 468 potentially relevant studies, 36 randomized controlled trials (RCTs) including 4887 patients, published between 1982 and 2016, were included in this systematic review. The treatment effect observed indicated marginal benefit of NSAIDs over opioids in initial pain reduction at 30min (11 RCTs, n=1985, mean difference [MD] -5.58, 95% confidence interval [CI] -10.22 to -0.95; heterogeneity I²=81%). In the subgroup analyses by the route of administration, NSAIDs required fewer rescue treatments (seven RCTs, n=541, number needed to treat [NNT] 11, 95% CI 6-75) and had lower vomiting rates compared with opioids (five RCTs, n=531, NNT 5, 95% CI 4-8). Comparisons of NSAIDs with paracetamol showed no difference for both drugs at 30min (four RCTs, n=1325, MD -5.67, 95% CI -17.52 to 6.18, p=0.35; I²=89%). Patients treated with NSAIDs required fewer rescue treatments (two trials, n=1145, risk ratio 0.56, 95% CI 0.42-0.74, p<0.001; I²=0%).

CONCLUSIONS

NSAIDs were equivalent to opioids or paracetamol in the relief of acute renal colic pain at 30min. There was less vomiting and fewer requirements for rescue analgesia with NSAIDs compared with opioids. Patients treated with NSAIDs required less rescue analgesia compared with paracetamol. Despite observed heterogeneity among the included studies and the overall quality of evidence, the findings of a lower need for rescue analgesia and fewer adverse events, in conjunction with the practical advantages of ease of delivery, suggest that NSAIDs should be the preferred analgesic option for patients presenting to the emergency department with renal colic.

PATIENT SUMMARY

In kidney stone-related acute pain episodes in patients with adequate renal function, treatment with nonsteroidal anti-inflammatory drugs offers effective and most sustained pain relief, with fewer side effects, when compared with opioids or paracetamol.

American Society for Enhanced Recovery (ASER) and Perioperative Quality Initiative (POQI) Joint Consensus Statement on Optimal Analgesia within an Enhanced Recovery Pathway for Colorectal Surgery: Part 2-From PACU to the Transition Home

BACKGROUND

Within an enhanced recovery pathway (ERP), the approach to treating pain should be multifaceted and the goal should be to deliver "optimal analgesia", which we define in this paper as a technique that optimizes patient comfort and facilitates functional recovery with the fewest medication side effects.

METHODS

With input from a multidisciplinary, international group of experts and through a structured review of the literature and use of a modified Delphi method, we achieved consensus surrounding the topic of optimal analgesia in the perioperative period for colorectal surgery patients.

DISCUSSION

As a part of the first Perioperative Quality Improvement (POQI) workgroup meeting, we sought to develop a consensus document describing a comprehensive, yet rational and practical, approach for developing an evidence-based plan for achieving optimal analgesia, specifically for a colorectal surgery within an ERP. The goal was twofold: (a) that application of this process would lead to improved patient outcomes and (b) that investigation of the questions raised would identify knowledge gaps to aid the direction for research into analgesia within ERPs in the years to come. This document details the evidence for a wide range of analgesic components, with particular focus on care in the post-anesthesia care unit, general care ward, and transition to home after discharge. The preoperative and operative consensus statement for analgesia was covered in Part 1 of this paper. The overall conclusion is that the combination of analgesic techniques employed in the perioperative period is not important as long as it is effective in delivering the goal of "optimal analgesia" as set forth in this document.

Midazolam as an active placebo in 3 fentanyl-validated nociceptive pain models

The use of inactive placebos in early translational trials of potentially analgesic compounds is discouraged because of the side-effect profiles of centrally acting analgesics. Therefore, benzodiazepines are used, although their use has not been validated in this context. Whether benzodiazepines confound the results of acute pain tests is unknown. Midazolam (0.06 mg/kg) as an active placebo was investigated in 3 nociceptive models that included contact heat, electrical pain, and pressure pain thresholds in 24 healthy volunteers. Fentanyl (1 μg/kg) served as an internal validator in this randomized, placebo (saline) controlled, 3-way cross-over trial. The primary outcome parameter (contact heat pain) was analyzed using a one-way, repeated measures analysis of variance and Tukey's post test. Midazolam did not reduce pain ([numeric rating scale], 0-100) in a statistically significant manner compared with placebo for the contact heat (mean difference -1.7, 95% confidence interval -10.6 to 7.3; P = 0.89) or electrical pain (4.3, -5.1 to 13.7; P = 0.51) test, nor did it raise the pressure pain thresholds (-28 kPa, -122; 64 kPa, P = 0.73). The width of the confidence intervals suggested that there were no clinically meaningful analgesic effects compared with the placebo. In contrast, the analgesic efficacy of fentanyl was effectively demonstrated in all 3 models (P < 0.01 vs midazolam and placebo). The findings of this study show that midazolam can be used as an active placebo in analgesic drug trials. Furthermore, the proposed models were simple to implement and very effective in detecting analgesia. The test battery can be used in translational trials for new compounds and comes with an active placebo and an optional active comparator.

Postoperative pain-from mechanisms to treatment

INTRODUCTION

Pain management after surgery continues to be suboptimal; there are several reasons including lack of translation of results from basic science studies and scientific clinical evidence into clinical praxis.

OBJECTIVES

This review presents and discusses basic science findings and scientific evidence generated within the last 2 decades in the field of acute postoperative pain.

METHODS

In the first part of the review, we give an overview about studies that have investigated the pathophysiology of postoperative pain by using rodent models of incisional pain up to July 2016. The second focus of the review lies on treatment recommendations based on guidelines and clinical evidence, eg, by using the fourth edition of the "Acute Pain Management: Scientific Evidence" of the Australian and New Zealand College of Anaesthetists and Faculty of Pain Medicine.

RESULTS

Preclinical studies in rodent models characterized responses of primary afferent nociceptors and dorsal horn neurons as one neural basis for pain behavior including resting pain, hyperalgesia, movement-evoked pain or anxiety- and depression-like behaviors after surgery. Furthermore, the role of certain receptors, mediators, and neurotransmitters involved in peripheral and central sensitization after incision were identified; many of these are very specific, relate to some modalities only, and are unique for incisional pain. Future treatment should focus on these targets to develop therapeutic agents that are effective for the treatment of postoperative pain as well as have few side effects. Furthermore, basic science findings translate well into results from clinical studies. Scientific evidence is able to point towards useful (and less useful) elements of multimodal analgesia able to reduce opioid consumption, improve pain management, and enhance recovery.

CONCLUSION

Understanding basic mechanisms of postoperative pain to identify effective treatment strategies may improve patients' outcome after surgery.

Low degree of satisfactory individual pain relief in post-operative pain trials

BACKGROUND

The majority of clinical trials regarding post-operative pain treatment focuses on the average analgesic efficacy, rather than on efficacy in individual patients. It has been argued, that in acute pain trials, the underlying distributions are often skewed, which makes the average unfit as the only way to measure efficacy. Consequently, dichotomised, individual responder analyses using a predefined 'favourable' response, e.g. Visual Analogue Scale (VAS) pain scores ≤ 30, have recently been suggested as a more clinical relevant outcome.

METHODS

We re-analysed data from 16 randomised controlled trials of post-operative pain treatment and from meta-analyses of a systematic review regarding hip arthroplasty. The predefined success criterion was that at least 80% of patients in active treatment groups should obtain VAS < 30 at 6 and 24 h post-operatively.

RESULTS

In the analysis of data from the randomised controlled trials, we found that at 6 h post-operatively, 50% (95% CI: 31-69) of patients allocated to active treatment reached the success criterion for pain at rest and 14% (95% CI: 5-34) for pain during mobilisation. At 24 h post-operatively, 60% (95% CI: 38-78) of patients allocated to active treatment reached the success criterion for pain at rest, and 15% (95% CI: 5-36) for pain during mobilisation. Similar results were found for trials from the meta-analyses.

CONCLUSION

Our results indicate that for conventional, explanatory trials of post-operative pain, individual patient's achievement of a favourable response to analgesic treatment is rather low. Future pragmatic clinical trials should focus on both average pain levels and individual responder analyses in order to promote effective pain treatment at the individually patient level.

Evaluation of two doses of etoricoxib, a COX-2 selective non-steroidal anti-inflammatory drug (NSAID), in the treatment of Rheumatoid Arthritis in a double-blind, randomized controlled trial

BACKGROUND

Treatment with non-steroidal anti-inflammatory drugs (NSAID) is a common component of treatment regimens for rheumatoid arthritis (RA). Etoricoxib is a COX-2 selective NSAID that has demonstrated efficacy in the treatment of RA at a dose of 90 mg. The current study further evaluated the efficacy of etoricoxib 60 mg and 90 mg in RA patients with active disease.

METHODS

This was a 2-part, double-blind, placebo-controlled study in RA (NCT01208181). Patients were required to have a diagnosis of RA (according to ARA 1987 revised classification criteria) and were to demonstrate symptom flare upon discontinuation of previous NSAID treatment prior to randomization. Part I was a 6-week, placebo-controlled period to assess the efficacy of etoricoxib 90 mg and etoricoxib 60 mg, each compared to placebo, as well as to each other. Part II was a 6-week period to evaluate the potential benefit of dose escalation from etoricoxib 60 mg to etoricoxib 90 mg after 6 weeks exposure to etoricoxib 60 mg in Part I compared to maintaining a steady dose of etoricoxib 60 mg throughout Parts I and II. Primary endpoints were Disease Activity Score evaluating 28 joints and C reactive protein level (DAS28-CRP) index and Patient Global Assessment of Pain (Pain) score (0-100 mm VAS) after 6 weeks of treatment in Part I. Adverse events were monitored throughout the study.

RESULTS

In total, 1404 patients were randomized in a 2:7:7:8 ratio; 1228 patients completed Part I and 713 patients continued to Part II. Both etoricoxib doses were superior to placebo on both primary efficacy endpoints (p = 0.004 for 60 mg and p = 0.034 for 90 mg for DAS28-CRP; p < 0.001 for both doses for PGAP) in Part I. Further in Part I, etoricoxib 90 mg was not significantly different from 60 mg for DAS28-CRP, but did demonstrate a small, but statistically significant decrease in baseline PGAP score vs. 60 mg (p = 0.019). In Part II, there was no significant decrease in PGAP score after increasing to 90 mg in subjects with inadequate pain relief on 60 mg as compared to subjects who stayed on 60 mg. The incidence of AEs and SAEs were similar between etoricoxib 60 mg and 90 mg in both Part I and II.

CONCLUSION

Both etoricoxib 90 mg and 60 mg are superior to placebo in relieving the symptoms of RA. Etoricoxib 90 mg vs 60 mg resulted in a statistically significant, though small, improvement in PGAP score, but not DAS28-CRP. Dose escalation from 60 mg to 90 mg in pain inadequate responders did not significantly improve efficacy. These results confirm the efficacy and tolerability of etoricoxib 90mg in patients with RA. In addition, this study demonstrated that etoricoxib 60 mg is also efficacious and well-tolerated in RA.

CLINICAL TRIAL REGISTRATION

NCT01208181 (registered September 22, 2010).