Acute pain Factors predictive of post-operative pain and opioid requirement in multimodal analgesia following knee replacement

Quantitative sensory testing and predicting outcomes for musculoskeletal pain, disability, and negative affect: a systematic review and meta-analysis

Hypersensitivity due to central pain mechanisms can influence recovery and lead to worse clinical outcomes, but the ability of quantitative sensory testing (QST), an index of sensitisation, to predict outcomes in chronic musculoskeletal disorders remains unclear. We systematically reviewed the evidence for ability of QST to predict pain, disability, and negative affect using searches of CENTRAL, MEDLINE, EMBASE, AMED, CINAHL, and PubMed databases up to April 2018. Title screening, data extraction, and methodological quality assessments were performed independently by 2 reviewers. Associations were reported between baseline QST and outcomes using adjusted (β) and unadjusted (r) correlations. Of the 37 eligible studies (n = 3860 participants), 32 were prospective cohort studies and 5 randomised controlled trials. Pain was an outcome in 30 studies, disability in 11, and negative affect in 3. Meta-analysis revealed that baseline QST predicted musculoskeletal pain (mean r = 0.31, 95% confidence interval [CI]: 0.23-0.38, n = 1057 participants) and disability (mean r = 0.30, 95% CI: 0.19-0.40, n = 290 participants). Baseline modalities quantifying central mechanisms such as temporal summation and conditioned pain modulation were associated with follow-up pain (temporal summation: mean r = 0.37, 95% CI: 0.17-0.54; conditioned pain modulation: mean r = 0.36, 95% CI: 0.20-0.50), whereas baseline mechanical threshold modalities were predictive of follow-up disability (mean r = 0.25, 95% CI: 0.03-0.45). Quantitative sensory testing indices of pain hypersensitivity might help develop targeted interventions aiming to improve outcomes across a range of musculoskeletal conditions.

APOLLO-2: A Randomized, Placebo and Active-Controlled Phase III Study Investigating Oliceridine (TRV130), a G Protein-Biased Ligand at the μ-Opioid Receptor, for Management of Moderate to Severe Acute Pain Following Abdominoplasty

Objectives

The clinical utility of conventional IV opioids is limited by the occurrence of opioid‐related adverse events. Oliceridine is a novel G protein–biased μ‐opioid receptor agonist designed to provide analgesia with an improved safety and tolerability profile. This phase III, double‐blind, randomized trial (APOLLO‐2 [NCT02820324]) evaluated the efficacy and safety of oliceridine for acute pain following abdominoplasty.

Methods

Patients received a loading dose of either placebo, oliceridine (1.5 mg), or morphine (4 mg), followed by demand doses via patient‐controlled analgesia (0.1, 0.35, or 0.5 mg oliceridine; 1 mg morphine; or placebo) with a 6‐minute lockout interval. The primary endpoint was the proportion of treatment responders over 24 hours for oliceridine regimens compared to placebo. Secondary outcomes included a predefined composite measure of respiratory safety burden (RSB, representing the cumulative duration of respiratory safety events) and the proportion of treatment responders vs. morphine.

Results

A total of 401 patients were treated with study medication. Effective analgesia was observed for all oliceridine regimens, with responder rates of 61.0%, 76.3%, and 70.0% for the 0.1‐, 0.35‐, and 0.5‐mg regimens, respectively, compared with 45.7% for placebo (all P < 0.05) and 78.3% for morphine. Oliceridine 0.35‐ and 0.5‐mg demand dose regimens were equi‐analgesic to morphine using a noninferiority analysis. RSB showed a dose‐dependent increase across oliceridine regimens (mean hours [standard deviation], 0.1 mg: 0.43 [1.56]; 0.35 mg: 1.48 [3.83]; 0.5 mg: 1.59 [4.26]; all comparisons not significant at P > 0.05 vs. placebo: 0.60 [2.82]). The RSB measure for morphine was 1.72 (3.86) (P < 0.05 vs. placebo). Gastrointestinal adverse events increased in a dose‐dependent manner across oliceridine demand dose regimens (0.1 mg: 49.4%; 0.35 mg: 65.8%; 0.5 mg: 78.8%; vs. placebo: 47.0%; and morphine: 79.3%). In comparison to morphine, the proportion of patients experiencing nausea or vomiting was lower with the 2 equi‐analgesic dose regimens of 0.35 and 0.5 mg oliceridine.

Conclusions

Oliceridine is a safe and effective IV analgesic for the relief of moderate to severe acute postoperative pain in patients undergoing abdominoplasty. Since the low‐dose regimen of 0.1 mg oliceridine was superior to placebo but not as effective as the morphine regimen, safety comparisons to morphine are relevant only to the 2 equi‐analgesic dose groups of 0.35 and 0.5 mg, which showed a favorable safety and tolerability profile regarding respiratory and gastrointestinal adverse effects compared to morphine. These findings support that oliceridine may provide a new treatment option for patients with moderate to severe acute pain where an IV opioid is warranted.

Pain Trajectory After Ankle Surgeries for Osteoarthritis

BACKGROUND:

The pain trajectory after ankle surgeries for osteoarthritis is relevant to describe. The purpose of this prospective study was to describe pain after ankle surgery and explore the link between perioperative factors and the development of postoperative pain.

METHODS:

Duration, severity, type of preoperative pain, psychological distress, opioid consumption, and type of surgery were evaluated in 49 patients who were followed for 18 months. Acute postoperative pain in the first 10 days after surgery was modeled by a pain trajectory. Univariate analysis was conducted to identify predictors of acute pain trajectory and chronic pain.

RESULTS:

Eighty-seven percent of patients had preoperative chronic pain, 34% had a high postoperative pain trajectory, 44% of whom reported chronic pain at 18 months. The patients who developed a high acute pain trajectory had higher preoperative opioid consumption (50% vs 19.4%, P = .04), a higher incidence of preoperative neuropathic pain (68.8% vs 32.3%, P = .02), a higher brief pain inventory score (51.5 vs 34, P = .01), and a higher psychological distress score (8 vs 3, P = .002). The patients who developed chronic pain had a higher brief pain inventory score (42 vs 33, P = .04), a higher psychological distress score (6 vs 4, P = .04), and a higher preoperative pain intensity (8 vs 6, P = .008). No association was found between the type of ankle surgery and pain.

CONCLUSION:

Patients with psychological distress and more severe preoperative pain were more at risk to develop acute pain and chronic pain after ankle surgery regardless of the surgery performed.

LEVEL OF EVIDENCE:

Level II, prospective comparative study.

Preoperative Patient Expectations of Postoperative Pain Are Associated with Moderate to Severe Acute Pain After VATS

OBJECTIVE

The goal of this post hoc analysis of subjects from a prospective observational study was to identify the predictors of patients developing moderate to severe acute pain (mean numerical rating scale [NRS] ≥4, 0-10) during the first three days after video-assisted thoracoscopic surgery (VATS) from a comprehensive evaluation of demographic, psychosocial, and surgical factors.

METHODS

Results from 82 patients who were enrolled one week before VATS and evaluated during the first three postoperative days are presented. The primary outcome variable of the current study was the presence of moderate to severe acute pain after VATS.

RESULTS

Fifty-nine percent (95% confidence interval, 47-69%) of study subjects developed moderate to severe acute pain after VATS. Factors univariately associated with the presence of moderate to severe acute pain were greater average expected postoperative pain, greater pain to a suprathreshold cold stimulus, and longer durations of surgery and hospital stay (P < 0.05). When considered in the multiple logistic regression models, the patients' preoperative average intensity of expected postoperative pain (NRS, 0-10) was the only measure associated with the moderate to severe acute pain. Average intensity of postoperative pain expected by patients when questioned preoperatively mediated the effect of reported intensity of pain to the suprathreshold cold stimulus for moderate to severe acute pain levels. Preoperative patient expectations had greater predictive value than other assessed variables including psychosocial factors such as catastrophizing or anxiety assessed one week before surgery.

CONCLUSIONS

None of the preoperative psychosocial measures were associated with the moderate to severe acute pain after VATS. Average expected postoperative pain was the only measure associated with the development of moderate to severe acute pain after VATS.

Preoperative quality-of-life measures predict acute postoperative pain in endoscopic sinus surgery

OBJECTIVES

Recent increases in opioid-related mortality have prompted a critical evaluation of postoperative pain management across all specialties. However, successfully limiting narcotic overprescription requires perioperative identification of patients who are at risk for high postoperative pain. Unfortunately, quality data to guide practice patterns are lacking. We therefore prospectively investigated several possible predictive factors of postoperative pain after endoscopic sinus surgery (ESS).

METHODS

Sixty-four consecutive patients undergoing ESS were enrolled. Baseline 22-item SinoNasal Outcomes Test (SNOT-22) and Short-Form 8 (SF-8) scores were obtained. Pain scores were collected postoperatively using a numeric rating scale. Spearman correlations and univariate linear regression models were used to investigate relationships between postoperative pain, patient factors, and SNOT-22/SF-8 domain scores. Multivariate linear regression was then performed to control for potential confounding variables.

RESULTS

Day-of-surgery pain scores were significantly correlated with the SF-8 role-physical domain (Rs = 0.32, P = 0.04). Whereas SF-8 pain scores were initially nonsignificant, at postoperative day 3 (POD3) the preoperative SF-8 pain score became correlated with self-reported pain (Rs = 0.39, P = 0.02). SNOT-22 total and subdomain scores were not associated with pain scores at any time point. Multivariate linear regression modelling identified baseline SF-8 role-physical and pain scores, smoking status, and undergoing a modified Lothrop procedure as significant independent predictors of POD3 pain (adjusted R² = 0.359, P < 0.0001).

CONCLUSION

Baseline patient-reported global quality-of-life measures are associated with postoperative pain after ESS. Large multicenter studies are necessary to validate these findings and investigate additional factors associated with postoperative pain following ESS.

LEVEL OF EVIDENCE

2c Laryngoscope, 129:1274-1279, 2019.

Early postoperative neuropathic pain assessed by the DN4 score predicts an increased risk of persistent postsurgical neuropathic pain

BACKGROUND

Acute neuropathic pain can occur in the postoperative period but any link with persistent post-surgical neuropathic pain remains unclear.

OBJECTIVES

The objectives of this study were to prospectively describe the incidence of acute post-surgical neuropathic pain in a large population using the DN4 (clinician administered) questionnaire and to confirm the hypothetical link between acute and persistent neuropathic pain at 2 months after surgery in a large population using the DN2 (self administered) questionnaire.

DESIGN

A multi-centre, prospective and observational trial.

SETTING

Two consecutive days in 27 hospitals in France.

PATIENTS

Six hundred and eight patients undergoing 13 different types of surgery. Fifteen patients were excluded as data were incomplete, and 229 (38.6%) and 260 (43.8%) were not contactable for assessment at 1 and 2 months after surgery, respectively.

MAIN OUTCOME MEASURES

Pain was evaluated at least 2 h postoperatively on the same day (D0),on the second day (D2) and at 1 and 2 months after surgery (M1 and M2). Pain was assessed using a 10-point Numeric Rating Scale. If the Numeric Rating Scale score was greater than 0, neuropathic pain was assessed using a DN4 (clinician administered) questionnaire or using a DN2 (self-administered) questionnaire. Acute and persistent postsurgical neuropathic pain (PPSNP) were defined respectively by a DN4 score at least 4/10 on day 0 and/or day 2 and a DN2 score at least 3/7 at 2 months after surgery.

RESULTS

Of the 593 patients included, 41.2% were in pain before surgery and 8.2% described neuropathic pain. Early after surgery, the majority of the 593 patients (72.2% on the day of surgery and 71.3% on day 2) experienced acute pain. It was neuropathic in nature in 5.6% of patients (95% CI, 3.6 to 8.3) on the day of surgery and 12.9% (95% CI, 9.7 to 16.7) on day 2. Two months after surgery, PPSNP was present in 33.3% of the 333 patients assessed. Multivariate analysis showed that a DN4 score at least 4/10 on the day of surgery or on day 2 was a significant risk factor for PPSNP [odds ratios 4.22 (95% CI, 2.19 to 8.12)].

CONCLUSION

Our results suggest that early acute postsurgical neuropathic pain significantly increases the risk of persistent post-surgical neuropathic pain.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NTC NCT02826317.

[High pain expectation and impairment from pre-existing pain are risk factors for severe postoperative pain : Results of a study using the Lübeck Pain Risk Questionnaire]

BACKGROUND

The intensity of postoperative pain is characterized by large interindividual variability. Furthermore, strong postoperative pain is known to influence physical recovery after surgery. High (preoperative) pain expectation and pre-existing pain, which are associated with pain-related disability (impairing pain) are risk factors for strong postoperative pain. They can be determined with the Lübeck Pain Risk Questionnaire used for the first time in this study. The aim of this study was to explore the hypothesis that patients with a combination of the characteristics (1) preoperative impairing pain and (2) high pain expectation are more likely to have strong postoperative pain. Patients with these characteristics represent a unique group of patients and are more likely to develop distinct postoperative pain and can therefore be characterized as a risk group.

MATERIAL AND METHODS

A total of 501 patients at the departments of general surgery, plastic surgery, trauma surgery and orthopedic surgery of the UKSH Campus Lübeck were included in this study. All underwent elective surgery. Study patients were 18 years and older. Those needing postoperative treatment in an intensive care unit were excluded from this study (n = 18). The characteristics "preoperative pain" and "pain expectation" were measured with the Lübeck Pain Risk Questionnaire the day before surgery. The primary outcome variable was the average postoperative pain intensity, which was measured with a numeric rating scale (NRS 0-10) and scores > 4 were defined as severe pain.

RESULTS

The NRS range for "preoperative pain" was subdivided as follows: "no pain" (NRS = 0), "functional pain" (NRS = 1-3), and "impairing pain" (NRS = 4-10); that for "pain expectation" as: "low expectation" (NRS = 0-4) and "high expectation" (NRS = 5-10). To determine these cut-off points, they were varied from > 1 to > 8 and those with highest effect size for strong postoperative pain were chosen. Patients with a high pain expectation had significantly stronger postoperative pain (p < 0.001) and significantly more often higher pain intensity than patients with a low expectation (53.3% vs. 20.6%, respectively, p < 0.001). Patients with pre-existing impairing pain had significantly stronger and more frequently higher postoperative pain than patients with pre-existing functional pain (43.4% vs. 18.4%, p < 0.05). Patients with a combination of the factors "preoperative impairing pain" and "high pain expectation" showed distinct postoperative pain with NRS > 4 significantly more often (59.4%, p < 0.001). These findings could be demonstrated for the departments general surgery, plastic surgery and trauma surgery.

CONCLUSION

The combination of both risk factors results in a unique risk group for the appearance of strong postoperative pain. This group can be economically determined in the daily clinical routine using the Lübeck Pain Risk Questionnaire. Further studies must be carried out to show if additional perioperative procedures can be profitable for the risk group identified with the Lübeck Pain Risk Questionnaire; however, patients falling outside the risk group must not be neglected because they too can develop severe postoperative pain.

Endogenous Opiates and Behavior: 2016

This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Factors Associated with Increased Experience of Postoperative Pain after Laparoscopic Gastric Bypass Surgery

INTRODUCTION

Patients with high body mass index (BMI), pre-existing pain and young age and women seem to experience more postoperative pain. Few studies have, however, addressed these risk factors amongst obese patients undergoing bariatric surgery. The aim of the present study was to evaluate risk factors for postoperative pain following laparoscopic gastric bypass surgery.

METHODS

In this cohort study, we used data from the PAIN OUT register for postoperative pain during the first 24 h after surgery. Primary outcome measure was severity of pain after surgery. Multivariate analyses were conducted to evaluate BMI, young age, gender and pre-existing pain as independent risk factors for postoperative pain.

RESULTS

We included 192 patients in this study. Younger age (B -0.08, 95%CI -0.11 to -0.05/year; p < 0.001), female gender (B 0.92, 95%CI 0.10-1.75; p = 0.029) and pre-existing pain (B 1.06, 95%CI 0.03-2.09; p = 0.044) were all associated with an increased risk for postoperative pain. In the multivariate analyses, only young age ((adjusted OR 0.95, 95%CI 0.92-0.97/year; p < 0.001) and pre-existing pain (adjusted OR 2.56, 95%CI 1.09-6.00; p = 0.031) remained as independent risk factors for severe postoperative pain.

CONCLUSION

Younger age and pre-existing pain are associated with severe postoperative pain during the first 24 h after laparoscopic gastric bypass surgery, whereas female gender and high BMI are not.

Prescription Opioid Analgesics Commonly Unused After Surgery: A Systematic Review

Importance

Prescription opioid analgesics play an important role in the treatment of postoperative pain; however, unused opioids may be diverted for nonmedical use and contribute to opioid-related injuries and deaths.

Objective

To quantify how commonly postoperative prescription opioids are unused, why they remain unused, and what practices are followed regarding their storage and disposal.

Evidence Review

MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched from database inception to October 18, 2016, for studies describing opioid oversupply for adults after a surgical procedure. The primary outcome-opioid oversupply-was defined as the number of patients with either filled but unused opioid prescriptions or unfilled opioid prescriptions. Two reviewers independently screened studies for inclusion, extracted data, and assessed the study quality.

Findings

Six eligible studies reported on a total of 810 unique patients (range, 30-250 patients) who underwent 7 different types of surgical procedures. Across the 6 studies, 67% to 92% of patients reported unused opioids. Of all the opioid tablets obtained by surgical patients, 42% to 71% went unused. Most patients stopped or used no opioids owing to adequate pain control, and 16% to 29% of patients reported opioid-induced adverse effects. In 2 studies examining storage safety, 73% to 77% of patients reported that their prescription opioids were not stored in locked containers. All studies reported low rates of anticipated or actual disposal, but no study reported US Food and Drug Administration-recommended disposal methods in more than 9% of patients.

Conclusions and Relevance

Postoperative prescription opioids often go unused, unlocked, and undisposed, suggesting an important reservoir of opioids contributing to nonmedical use of these products, which could cause injuries or even deaths.

Essential Elements of Multimodal Analgesia in Enhanced Recovery After Surgery (ERAS) Guidelines

Perioperative multimodal analgesia uses combinations of analgesic medications that act on different sites and pathways in an additive or synergistic manner to achieve pain relief with minimal or no opiate consumption. Although all medications have side effects, opiates have particularly concerning, multisystemic, long-term, and short-term side effects, which increase morbidity and prolong admissions. Enhanced recovery is a systematic process addressing each aspect affecting recovery. This article outlines the evidence base forming the current multimodal analgesia recommendations made by the Enhanced Recovery After Surgery Society (ERAS). We describe current evidence and important future directions for effective perioperative multimodal analgesia in enhanced recovery pathways.

Poorly controlled postoperative pain: prevalence, consequences, and prevention

This review provides an overview of the clinical issue of poorly controlled postoperative pain and therapeutic approaches that may help to address this common unresolved health-care challenge. Postoperative pain is not adequately managed in greater than 80% of patients in the US, although rates vary depending on such factors as type of surgery performed, analgesic/anesthetic intervention used, and time elapsed after surgery. Poorly controlled acute postoperative pain is associated with increased morbidity, functional and quality-of-life impairment, delayed recovery time, prolonged duration of opioid use, and higher health-care costs. In addition, the presence and intensity of acute pain during or after surgery is predictive of the development of chronic pain. More effective analgesic/anesthetic measures in the perioperative period are needed to prevent the progression to persistent pain. Although clinical findings are inconsistent, some studies of local anesthetics and nonopioid analgesics have suggested potential benefits as preventive interventions. Conventional opioids remain the standard of care for the management of acute postoperative pain; however, the risk of opioid-related adverse events can limit optimal dosing for analgesia, leading to poorly controlled acute postoperative pain. Several new opioids have been developed that modulate μ-receptor activity by selectively engaging intracellular pathways associated with analgesia and not those associated with adverse events, creating a wider therapeutic window than unselective conventional opioids. In clinical studies, oliceridine (TRV130), a novel μ-receptor G-protein pathway-selective modulator, produced rapid postoperative analgesia with reduced prevalence of adverse events versus morphine.

Multimodal Analgesia Versus Intravenous Patient-Controlled Analgesia for Minimally Invasive Transforaminal Lumbar Interbody Fusion Procedures

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To compare postoperative narcotic consumption and pain scores between multimodal analgesia (MMA) and patient-controlled analgesia (PCA) following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

SUMMARY OF BACKGROUND DATA

A multimodal analgesic approach to pain management may lead to decreased pain and narcotic consumption after orthopedic procedures. Additional evidence is, however, required to determine how MMA compares to intravenous PCA after MIS TLIF.

METHODS

Patients undergoing 1-level MIS TLIF followed by either MMA or PCA at our institution were compared in terms of inpatient pain scores, narcotic consumption, hospital length of stay, rates of surgical complications, rates of inpatient nausea/vomiting, rates of postoperative urinary retention, and rates of narcotic consumption during the months after discharge.

RESULTS

A total of 139 patients met inclusion criteria. Of these, 39 (28.1%) received MMA and 100 (71.9%) received PCA. Demographic and comorbidity characteristics did not differ between cohorts. Compared with patients receiving PCA, patients receiving MMA had a lower rate of inpatient narcotic consumption (2.8 ± 1.9 vs. 5.3 ± 4.4 oral morphine equivalents/hour, P < 0.001), a lower rate of inpatient nausea/vomiting (20.5% vs. 48.0%; P = 0.003), and a shorter hospital length of stay (53.0 ± 25.3 vs. 62.6 ± 24.4 h, P = 0.041). There were no differences in Numeric Rating Scale pain score between cohorts for day 0, postoperative day 1, or postoperative day 2 (P > 0.05 for each). There was no difference in the rate of postoperative urinary retention (P > 0.05). Similarly, there were no differences in narcotic consumption at 6 or 12 weeks postoperatively (P > 0.05 for each).

CONCLUSION

These findings suggest that MMA results in reduced inpatient hospital narcotic consumption compared with PCA after MIS TLIF. The decrease in narcotic consumption may contribute to the observed decrease in the rate of inpatient nausea/vomiting and shorter hospital length of stay. Importantly, MMA and PCA resulted in similar analgesia for patients during the inpatient stay.

LEVEL OF EVIDENCE

4.

Quantitative sensory testing measures individual pain responses in emergency department patients

Background

Refining and individualizing treatment of acute pain in the emergency department (ED) is a high priority, given that painful complaints are the most common reasons for ED visits. Few tools exist to objectively measure pain perception in the ED setting. We speculated that variation in perception of fixed painful stimuli would explain individual variation in reported pain and response to treatment among ED patients.

Materials and methods

In three studies, we 1) describe performance characteristics of brief quantitative sensory testing (QST) in 50 healthy volunteers, 2) test effects of 10 mg oxycodone versus placebo on QST measures in 18 healthy volunteers, and 3) measure interindividual differences in nociception and treatment responses in 198 ED patients with a painful complaint during ED treatment. QST measures adapted for use in the ED included pressure sensation threshold, pressure pain threshold (PPT), pressure pain response (PPR), and cold pain tolerance (CPT) tests.

Results

First, all QST measures had high inter-rater reliability and test–retest reproducibility. Second, 10 mg oxycodone reduced PPR, increased PPT, and prolonged CPT. Third, baseline PPT and PPR revealed hyperalgesia in 31 (16%) ED subjects relative to healthy volunteers. In 173 (88%) ED subjects who completed repeat testing 30 minutes after pain treatment, PPT increased and PPR decreased (Cohen’s d_z 0.10–0.19). Verbal pain scores (0–10) for the ED complaint decreased by 2.2 (95% confidence intervals [CI]: 1.9, 2.6) (Cohen’s d_z 0.97) but did not covary with the changes in PPT and PPR (r=0.05–0.13). Treatment effects were greatest in ED subjects with a history of treatment for anxiety or depression (Cohen’s d_z 0.26–0.43) or with baseline hyperalgesia (Cohen’s d_z 0.40–0.88).

Conclusion

QST reveals individual differences in perception of fixed painful stimuli in ED patients, including hyperalgesia. Subgroups of ED patients with hyperalgesia and psychiatric history report larger treatment effects on ED pain and QST measures.

A comparison of predictors and intensity of acute postsurgical pain in patients undergoing total hip and knee arthroplasty

Background

Acute pain is an expected result after surgery. Nevertheless, when not appropriately controlled, acute pain has a very negative impact on individual clinical outcomes, impairing healing and recovery, and has clear consequences on health care system costs. Augmenting knowledge on predictors and potentially modifiable determinants of acute postsurgical pain can facilitate early identification of and intervention in patients at risk. However, only a few studies have examined and compared acute pain after total hip arthroplasty (THA) and total knee arthroplasty (TKA). The aim of this study was to compare THA and TKA in acute postsurgical pain intensity and its predictors.

Methods

A consecutive sample of 124 patients with osteoarthritis (64 undergoing THA and 60 TKA) was assessed 24 hours before (T1) and 48 hours after (T2) surgery. Demographic, clinical, and psychological factors were assessed at T1, and acute postsurgical pain experience was examined at T2. Additionally, the same hierarchical regression analysis was performed separately for each arthroplasty type.

Results

TKA patients reported higher levels of acute postsurgical pain compared with THA (t=8.490, p=0.004, d=0.527, 95% confidence interval, 0.196–0.878). In the final THA predictive model, presurgical pain was the only variable approaching significant results (t[57]=1.746, β=0.254, p=0.086). In the final TKA predictive model, optimism was the only predictor of pain (t[51]=−2.518, β=−0.339, p=0.015), with emotional representation (t[51]=1.895, β=0.254, p=0.064) presenting a trend toward significance.

Conclusion

The current study is the first examining THA and TKA differences on acute postsurgical pain intensity and its predictors using a multivariate approach. Results from this study could prove useful for the design of distinct interventions targeting acute postsurgical pain management depending on whether the site of arthroplasty is the hip or the knee. Finally, the current results also support the argument that these two surgeries, at least with regard to acute pain, should be approached separately.

Are preoperative experimental pain assessments correlated with clinical pain outcomes after surgery? A systematic review

BACKGROUND

Pain after surgery is not uncommon with 30% of patients reporting moderate to severe postoperative pain. Early identification of patients prone to postoperative pain may be a step forward towards individualized pain medicine providing a basis for improved clinical management through treatment strategies targeting relevant pain mechanisms in each patient. Assessment of pain processing by quantitative sensory testing (QST) prior to surgery has been proposed as a method to identify patients at risk for postoperative pain, although results have been conflicting. Since the last systematic review, several studies investigating the association between postoperative pain and more dynamic measures of pain processing like temporal summation of pain and conditioned pain modulation have been conducted.

OBJECTIVES

According to the PRISMA guidelines, the aim of this systematic review was to evaluate whether assessment of experimental pain processing including measures of central pain mechanisms prior to surgery was associated with pain intensity after surgery.

METHODS

Systematic database searches in PubMed and EMBASE with the following search components: QST, association, and postoperative pain, for studies that assessed the association between QST and pain after surgery were performed. Two authors independently reviewed all titles and abstracts to assess their relevance for inclusion. Studies were included if (1) QST was performed prior to surgery, (2) pain was assessed after surgery, and (3) the association between QST and pain after surgery was investigated. Forty-four unique studies were identified, with 30 studies on 2738 subjects meeting inclusion criteria. The methodological quality of the include studies was assessed and data extraction included study population, type of surgery, QST variables, clinical pain outcome measure and main result.

RESULTS

Most studies showed moderate to high risk of bias. Type of surgery investigated include 7 studies on total knee replacement, 5 studies on caesarean section, 4 studies on thoracic surgery, 2 studies on herniotomy, 2 studies on hysterectomy/myomectomy, 1 study on tubal ligation, 1 study on gynecologic laparoscopy, 1 study on arthroscopic knee surgery, 1 study on shoulder surgery, 1 study on disc herniation surgery, 1 study on cholecystectomy, 1 study on percutaneous nephrolithotomy, 1 study on molar surgery, 1 study on abdominal surgery, and 1 study on total knee replacement and total hip replacement. The majority of the preoperative QST variables showed no consistent association with pain intensity after surgery. Thermal heat pain above the pain threshold and temporal summation of pressure pain were the QST variables, which showed the most consistent association with acute or chronic pain after surgery.

CONCLUSIONS

QST before surgery does not consistently predict pain after surgery. High quality studies investigating the presence of different QST variables in combination or along with other pain-related psychosocial factors are warranted to confirm the clinical relevance of QST prior to surgery.

IMPLICATIONS

Although preoperative QST does not show consistent results, future studies in this area should include assessment of central pain mechanisms like temporal summation of pressure pain, conditioned pain modulation, and responses to pain above the pain threshold since these variables show promising associations to pain after surgery.

Efficacy and safety of Postoperative Intravenous Parecoxib sodium Followed by ORal CElecoxib (PIPFORCE) post-total knee arthroplasty in patients with osteoarthritis: a study protocol for a multicentre, double-blind, parallel-group trial

INTRODUCTION

Total knee arthroplasty (TKA) has been regarded as a most painful orthopaedic surgery. Although many surgeons sequentially use parecoxib and celecoxib as a routine strategy for postoperative pain control after TKA, high quality evidence is still lacking to prove the effect of this sequential regimen, especially at the medium-term follow-up. The purpose of this study, therefore, is to evaluate efficacy and safety of postoperative intravenous parecoxib sodium followed by oral celecoxib in patients with osteoarthritis (OA) undergoing TKA. The hypothesis is that compared to placebo with opioids as rescue treatment, sequential use of parecoxib and celecoxib can achieve less morphine consumption over the postoperative 2 weeks, as well as better pain control, quicker functional recovery in the postoperative 6 weeks and less opioid-related adverse events during the 12-week recovery phase.

METHODS AND ANALYSIS

This study is designed as a multicentre, randomised, double-blind, parallel-group and placebo-controlled trial. The target sample size is 246. All participants who meet the study inclusion and exclusion criteria will be randomly assigned in a 1:1 ratio to either the parecoxib/celecoxib group or placebo group. The randomisation and allocation will be study site based. The study will consist of three phases: an initial screening phase; a 6-week double-blind treatment phase; and a 6-week follow-up phase. The primary end point is cumulative opioid consumption during 2 weeks postoperation. Secondary end points consist of the postoperative visual analogue scale score, knee joint function, quality of life, local skin temperature, erythrocyte sedimentation rate, C reactive protein, cytokines and blood coagulation parameters. Safety end points will be monitored too.

ETHICS AND DISSEMINATION

Ethics approval for this study has been obtained from the Ethics Committee, Peking Union Medical College Hospital, China (Protocol number: S-572) Study results will be available as published manuscripts and presentations at national and international meetings.

TRIAL REGISTRATION NUMBER

NCT02198924.