Different pain responses to chronic and acute pain in various ethnic/racial groups

Association Between Early Surgery and Postoperative Opioid Use in Patients With Lumbar Disc Herniation: A Propensity Score-Matching Analysis Using an Administrative Claims Database in Japan

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

This study aimed to investigate whether early surgery shortens the duration of opioid use in patients who underwent surgery with lumbar disc herniation.

METHODS

We extracted patients who underwent surgery at least 2 weeks after they were diagnosed with lumbar disc herniation between April 2014 and May 2021. Opioid use after surgery was compared between patients who underwent surgery within 90 days (early surgery group) and 90 days or later (late surgery group). Propensity-score-matching analysis and multivariable Cox hazard regression analysis with a restricted cubic spline model were conducted to evaluate the association between the timing of surgery and termination of opioid use after surgery.

RESULTS

A total of 1597 eligible patients were identified, with 807 (51%) in the early surgery group. In the propensity-score-matched cohort, the early surgery group had a significantly lower proportion of opioid use than the control group (28% vs 48%, percent difference -20%, P < .001). Multivariable Cox hazard regression analysis showed that early surgery was significantly associated with the earlier termination of opioid use (HR, 3.13; 95% CI, 1.97-4.97; P < .001). Restricted cubic spline model showed a monotonically decreased hazard ratio and decreased hazard ratio of .50 in patients who underwent surgery 111 days or later after the diagnosis.

CONCLUSIONS

Early surgery, especially within 90 days, was associated with earlier opioid use termination after surgery. Regarding the duration of opioid use following surgery, surgical treatment may be preferable to perform within around 4 months after the diagnosis.

The Skeletal Oncology Research Group Machine Learning Algorithm (SORG-MLA) for predicting prolonged postoperative opioid prescription after total knee arthroplasty: an international validation study using 3,495 patients from a Taiwanese cohort

BACKGROUND

Preoperative prediction of prolonged postoperative opioid use (PPOU) after total knee arthroplasty (TKA) could identify high-risk patients for increased surveillance. The Skeletal Oncology Research Group machine learning algorithm (SORG-MLA) has been tested internally while lacking external support to assess its generalizability. The aims of this study were to externally validate this algorithm in an Asian cohort and to identify other potential independent factors for PPOU.

METHODS

In a tertiary center in Taiwan, 3,495 patients receiving TKA from 2010-2018 were included. Baseline characteristics were compared between the external validation cohort and the original developmental cohorts. Discrimination (area under receiver operating characteristic curve [AUROC] and precision-recall curve [AUPRC]), calibration, overall performance (Brier score), and decision curve analysis (DCA) were applied to assess the model performance. A multivariable logistic regression was used to evaluate other potential prognostic factors.

RESULTS

There were notable differences in baseline characteristics between the validation and the development cohort. Despite these variations, the SORG-MLA ( https://sorg-apps.shinyapps.io/tjaopioid/ ) remained its good discriminatory ability (AUROC, 0.75; AUPRC, 0.34) and good overall performance (Brier score, 0.029; null model Brier score, 0.032). The algorithm could bring clinical benefit in DCA while somewhat overestimating the probability of prolonged opioid use. Preoperative acetaminophen use was an independent factor to predict PPOU (odds ratio, 2.05).

CONCLUSIONS

The SORG-MLA retained its discriminatory ability and good overall performance despite the different pharmaceutical regulations. The algorithm could be used to identify high-risk patients and tailor personalized prevention policy.

A machine learning algorithm for predicting prolonged postoperative opioid prescription after lumbar disc herniation surgery. An external validation study using 1,316 patients from a Taiwanese cohort

BACKGROUND CONTEXT

Preoperative prediction of prolonged postoperative opioid prescription helps identify patients for increased surveillance after surgery. The SORG machine learning model has been developed and successfully tested using 5,413 patients from the United States (US) to predict the risk of prolonged opioid prescription after surgery for lumbar disc herniation. However, external validation is an often-overlooked element in the process of incorporating prediction models in current clinical practice. This cannot be stressed enough in prediction models where medicolegal and cultural differences may play a major role.

PURPOSE

The authors aimed to investigate the generalizability of the US citizens prediction model SORG to a Taiwanese patient cohort.

STUDY DESIGN

Retrospective study at a large academic medical center in Taiwan.

PATIENT SAMPLE

Of 1,316 patients who were 20 years or older undergoing initial operative management for lumbar disc herniation between 2010 and 2018.

OUTCOME MEASURES

The primary outcome of interest was prolonged opioid prescription defined as continuing opioid prescription to at least 90 to 180 days after the first surgery for lumbar disc herniation at our institution.

METHODS

Baseline characteristics were compared between the external validation cohort and the original developmental cohorts. Discrimination (area under the receiver operating characteristic curve and the area under the precision-recall curve), calibration, overall performance (Brier score), and decision curve analysis were used to assess the performance of the SORG ML algorithm in the validation cohort. This study had no funding source or conflict of interests.

RESULTS

Overall, 1,316 patients were identified with sustained postoperative opioid prescription in 41 (3.1%) patients. The validation cohort differed from the development cohort on several variables including 93% of Taiwanese patients receiving NSAIDS preoperatively compared with 22% of US citizens patients, while 30% of Taiwanese patients received opioids versus 25% in the US. Despite these differences, the SORG prediction model retained good discrimination (area under the receiver operating characteristic curve of 0.76 and the area under the precision-recall curve of 0.33) and good overall performance (Brier score of 0.028 compared with null model Brier score of 0.030) while somewhat overestimating the chance of prolonged opioid use (calibration slope of 1.07 and calibration intercept of -0.87). Decision-curve analysis showed the SORG model was suitable for clinical use.

CONCLUSIONS

Despite differences at baseline and a very strict opioid policy, the SORG algorithm for prolonged opioid use after surgery for lumbar disc herniation has good discriminative abilities and good overall performance in a Han Chinese patient group in Taiwan. This freely available digital application can be used to identify high-risk patients and tailor prevention policies for these patients that may mitigate the long-term adverse consequence of opioid dependence: https://sorg-apps.shinyapps.io/lumbardiscopioid/.

Update to 2019-2022 ONS Research Agenda: Rapid Review to Promote Equity in Oncology Healthcare Access and Workforce Development

PURPOSE

The Oncology Nursing Society (ONS) tasked a rapid response research team (RRRT) to develop priorities to increase diversity, equity, and inclusivity in oncology clinical care and workforce development.

METHODS

An RRRT of experts in health disparities conducted a rapid review of the literature, consulted with oncology nurse leaders and disparities researchers, and reviewed priorities from funding agencies.

RESULTS

Significant gaps in the current oncology disparities literature were identified and used to inform priority areas for future research practice and workforce development in oncology nursing.

SYNTHESIS

This is the second article in a two-part series that presents findings on structural racism and health inequities in oncology nursing. In the first article, three priority areas for oncology nursing research were presented. In this article, strategies to improve diversity, equity, and inclusivity in clinical practice and the oncology workforce are described.

IMPLICATIONS FOR RESEARCH

Recommendations are presented to inform research, clinical, administrative, and academic oncology nursing settings on increasing diversity, equity, and inclusivity and deconstructing structural racism.

Ilex paraguariensis extract as an alternative to pain medications

Pain is a common and distressing symptom of many diseases and its clinical treatment generally involves analgesics and anti-inflammatory drugs. This study evaluated the toxicity of Ilex paraguariensis A. St.-Hil. (Aquifoliaceae) aqueous extract (leaves, petioles and branches) and its performance in a nociceptive response. Hepatotoxicity, psycho-stimulant test and evaluation of enzyme markers for liver damage were also tested. Chromatographic analysis by UPLC-MS demonstrated a series of isomeric monocaffeoylquinic acids, isomers of dicaffeoylquinic acid, flavonol glycosides, and saponins. Phase I and II of nociception were obtained for meloxicam, dexamethasone and aqueous Ilex paraguariensis extract. Ilex paraguariensis extract concentration was negatively correlated (R = -0.887) with alanine aminotransferase (p < 0.05) in acetaminophen-induced hepatotoxicity test, indicating hepatoprotective activity of this extract. Ilex paraguariensis extract also presented analgesic properties equivalent to drugs that already have proven efficacy. Notably, the administration of multiple doses of Ilex paraguariensis extract was considered safe from the therapeutic point of view.

Examining the Association of Pain and Financial Hardship Among Older Men by Race in the United States

Pain associated with financial hardship among older men varies by race. The purpose of this study was to examine the association of financial hardship with the presence of pain in men 50 years and older by race. Using the Health and Retirement Study (HRS) 2010 wave, bivariate and multivariate logistic regression models were used to assess the association between four financial hardship indicators and total financial hardship as a composite score, and the presence of pain by race. Among White men, the association between the presence of pain and hardship controlling for demographic factors was statistically significant across four indicators and one composite score: ongoing financial hardship (OR = 1.29, 95% CI [1.02, 1.64]), food insecurity (OR = 2.55, 95% CI [1.51, 4.31]), taking less medication due to cost (OR = 2.12, 95% CI [1.40, 3.22]), difficulty paying bills (OR = 1.36, 95% CI [1.07, 1.73]), and total financial hardship (OR = 1.27, 95% CI [1.12, 1.44]). Among African American men, the association between the presence of pain and taking less medication due to cost (OR = 2.99, 95% CI [1.31, 6.85]) was significant. With increasing comorbidities among older adults, particularly African Americans, it is imperative to fully understand the mechanisms of this underexplored area in both the pain and financial hardship literature.

Prevalence and sites of pain in remote-living older Aboriginal Australians, and associations with depressive symptoms and disability

BACKGROUND

Pain is a growing public health problem associated with significant health and functional implications. Limited data exist for Aboriginal Australians.

AIMS

To describe the prevalence, severity and sites of pain, analgesic use and associated factors, including depression and disability, in remote-living Aboriginal Australians.

METHODS

Cross-sectional study of 263 Aboriginal Australians aged ≥45 years from six remote Indigenous communities and the town of Derby in the Kimberley region of Western Australia between 2011 and 2013. Pain was assessed using a culturally adapted pain scale. Factors associated with pain were investigated with binary logistic regression.

RESULTS

One hundred and seventy (64.6%) participants reported having pain and 53 (20.2%) reported persistent pain. Of those reporting pain, 61 (35.9%) rated it as moderate and 70 (41.2%) as severe. The most common sites of pain were back and knee, and 38 (22.4%) participants with pain indicated three or more sites of pain. Only 70 (41.2%) participants with pain were on some type of analgesic medication. After adjustment, poor vision (odds ratio (OR) = 2.21; 95% confidence interval (CI) 1.22-4.00), hypertension (OR = 1.89; 95% CI 1.03-3.45) and heart problems (OR = 2.05; 95% CI 1.01-4.14) were associated with pain. Higher depression scores were associated with more persistent pain, but pain was not significantly associated with clinically relevant depressive symptoms, or requiring assistance with two or more personal and/or instrumental activities of daily living.

CONCLUSION

High levels of pain were reported, although the prevalence of persistent pain was comparable to the general population. Identifying risk factors, improving pain recognition and assessment and evaluating culturally tailored management approaches should be a priority.

Evaluation of antinociceptive activity of Ilex dipyrena Wall. in mice

BACKGROUND

In order to find a new natural resource for pain-relief, the analgesic effects of Ilex dipyrena crude extract, fractions, and subfractions were evaluated in in-vivo mouse models with possible mechanism of action.

METHODS

Analgesic effects of crude extract (100 and 200 mg/kg body weight), fractions and subfractions (75 mg/kg body weight) were screened using heat-induced (tail-immersion and hot plate test) and chemical-induced (formalin and acetic acid) nociception models in mice. The samples were also tested for the elucidation of a possible mechanism through opioidergic and GABAergic systems.

RESULTS

The administration of crude extract, fractions and subfractions produced analgesic responses in acetic acid, formalin, tail immersion, and hot plate model for pain similar to those obtained with the standard. Naloxone antagonized the antinociceptive effects of the tested samples, whereas bicuculline showed partial inhibition. Considering the analgesic response, crude extract, fractions, and subfractions demonstrated promising inhibitory activity against all test models for pain, which was further supported by the possible involvement of opioidergic and GABAergic systems.

CONCLUSION

The results suggest that this plant may be useful in the development of new analgesic drugs. Further research with regard to the isolation of bioactive compounds is required to verify these findings.

Racial and ethnic disparities in opioid use for adolescents at US emergency departments

Background

Racial/ethnic disparities in the use of opioids to treat pain disorders have been previously reported in the emergency department (ED). Further research is needed to better evaluate the impact race/ethnicity may have on the use of opioids in adolescents for the management of pain disorders in the ED.

Methods

This was a cross-sectional study using data from the National Hospital Ambulatory Medical Care Survey from 2006 to 2016. Multivariate models were used to evaluate the role of race/ethnicity in the receipt of opioid agonists while in the ED. All ED visits with patients aged 11–21 years old were analyzed. Races/ethnicities were stratified as non-Hispanic Whites, non-Hispanic Blacks, and Hispanics. In addition to race, statistical analysis included the following covariates: pain score, pain diagnosis, age, region, sex, and payment method.

Results

There was a weighted total of 189,256,419 ED visits. Those visits involved 109,826,315 (58%) non-Hispanic Whites, 46,314,977 (24%) non-Hispanic Blacks, and 33,115,127 (18%) Hispanics, with 21.6% (95% CI, 21.1%-22.1), 15.2% (95% CI, 14.6–15.9%), and 17.4% (95% CI, 16.5–18.2%) of those visits reporting use of opioids, respectively. Regardless of age, sex, and region, non-Hispanic Whites received opioids at a higher rate than non-Hispanic Blacks and Hispanics. Based on diagnosis, non-Hispanic Whites received opioids at a higher rate in multiple pain diagnoses. Additionally, non-Hispanic Blacks and Hispanics were less likely to receive an opioid when reporting moderate pain (aOR = 0.738, 95% CI 0.601–0.906, aOR = 0.739, 95% CI 0.578–0.945, respectively) and severe pain (aOR = 0.580, 95% CI 0.500–0.672, aOR = 0.807, 95% CI 0.685–0.951, respectively) compared to non-Hispanic Whites.

Conclusions

Differences in the receipt of opioid agonists in EDs among the races/ethnicities exist, with more non-Hispanic Whites receiving opioids than their minority counterparts. Non-Hispanic Black women may be an especially marginalized population. Further investigation into sex-based and regional differences are needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02715-y.

Racial and Ethnic Disparities in the Treatment of Chronic Pain

OBJECTIVE

To summarize the current literature on disparities in the treatment of chronic pain.

METHODS

We focused on studies conducted in the United States and published from 2000 and onward. Studies of cross-sectional, longitudinal, and interventional designs were included.

RESULTS

A review of the current literature revealed that an adverse association between non-White race and treatment of chronic pain is well supported. Studies have also shown that racial differences exist in the long-term monitoring for opioid misuse among patients suffering from chronic pain. In addition, a patient's sociodemographic profile appears to influence the relationship between chronic pain and quality of life. Results from interventional studies were mixed.

CONCLUSIONS

Disparities exist within the treatment of chronic pain. Currently, it is unclear how to best combat these disparities. Further work is needed to understand why disparities exist and to identify points in patients' treatment when they are most vulnerable to unequal care. Such work will help guide the development and implementation of effective interventions.

Sorting pain out of salience: assessment of pain facial expressions in the human fetus

Supplemental Digital Content is Available in the Text.

Acute pain facial expressions can be detected/scored in human fetuses. We propose a seven-item scale to differentiate pain facial expressions from rest/acoustic stimuli ones.

Introduction:

The question of whether the human fetus experiences pain has received substantial attention in recent times. With the advent of high-definition 4-dimensional ultrasound (4D-US), it is possible to record fetal body and facial expressions.

Objective:

To determine whether human fetuses demonstrate discriminative acute behavioral responses to nociceptive input.

Methods:

This cross-sectional study included 5 fetuses with diaphragmatic hernia with indication of intrauterine surgery (fetoscopic endoluminal tracheal occlusion) and 8 healthy fetuses, who were scanned with 4D-US in 1 of 3 conditions: (1) acute pain group: Fetuses undergoing intrauterine surgery were assessed in the preoperative period during the anesthetic injection into the thigh; (2) control group at rest: Facial expressions at rest were recorded during scheduled ultrasound examinations; and (3) control group acoustic startle: Fetal facial expressions were recorded during acoustic stimulus (500–4000 Hz; 60–115 dB).

Results:

Raters blinded to the fetuses’ groups scored 65 pictures of fetal facial expressions based on the presence of 12 items (facial movements). Analyses of redundancy and usefulness excluded 5 items for being of low discrimination capacity (P>0.2). The final version of the pain assessment tool consisted of a total of 7 items: brow lowering/eyes squeezed shut/deepening of the nasolabial furrow/open lips/horizontal mouth stretch/vertical mouth stretch/neck deflection. Odd ratios for a facial expression to be detected in acute pain compared with control conditions ranged from 11 (neck deflection) to 1,400 (horizontal mouth stretch). Using the seven-item final tool, we showed that 5 is the cutoff value discriminating pain from nonpainful startle and rest.

Conclusions:

This study inaugurates the possibility to study pain responses during the intrauterine life, which may have implications for the postoperative management of pain after intrauterine surgical interventions

Open-Label Placebo Trial among Japanese Patients with Chronic Low Back Pain

Background

The aim of this study was to confirm the effectiveness of open-label placebo (OLP) in Japanese patients with chronic low back pain (CLBP), similar to previous reports, and to investigate its short- and medium-term effects in this study population.

Methods

Fifty-two patients with CLBP were randomized into a treatment as usual (TAU) group (n = 26) or an OLP + TAU group (n = 26) for 12 weeks. The TAU included advice to remain active and exercise in conjunction with recent psychological education based on a self-management strategy. In contrast, participants in the OLP + TAU group were instructed to take two OLP capsules a day. Outcome measures were assessed at baseline and at weeks 3 and 12 using the Roland–Morris Disability Questionnaire (RMDQ), Numerical Rating Scale (NRS) for pain intensity, and the Timed-Up-and-Go (TUG) test. Difference in outcomes between the two groups was compared at the two follow-up points.

Results

Although all participants completed the 3-week follow-up, four patients (two in each group) were lost to follow-up beyond week 3. There were no significant intergroup differences in changes in the RMDQ score (p=0.40), pain-NRS score (p=0.19), and TUG time (p=0.98) at week 3. Two-way repeated measure analyses of covariance showed significant time-course effects but did not show group effects or any interactions between the time-course and group in terms of the RMDQ score. However, it did not show any effects in the pain-NRS score and TUG time at week 12.

Conclusions

The OLP + TAU group showed no superior findings in comparison with the TAU group after 3 weeks and 12 weeks for Japanese patients with CLBP. Nonetheless, significant improvements in functional disability were observed in both groups.

The influence of sleep disturbances and sleep disorders on pain outcomes among veterans: A systematic scoping review

Chronic nonmalignant pain, sleep disturbances and sleep disorders are highly prevalent conditions among U.S. military veterans. Evidence summaries highlight the influence of sleep on pain outcomes in the general adult population but not for the military veteran population. This is a significant gap as U.S. military veterans are an exceedingly high-risk population for both chronic pain and sleep disturbances and/or disorders. We aimed to review the influence of sleep disturbances and sleep disorders on pain outcomes among veterans with chronic nonmalignant pain. A systematic scoping review was conducted using PubMed/Medline, EMBASE, Scopus, CINAHL, and PsycINFO. Twenty-six out of 1450 studies from initial search were included in this review resulting in a combined sample size of N = 923,434 participants. Sleep disturbances and sleep disorders were associated with worse pain outcomes among veterans with chronic pain. Treatment-induced sleep improvements ameliorated pain outcomes in veterans with sleep disorders and sleep disturbances. Research is indicated to address an overlooked pain treatment opportunity - that of sleep disturbance and sleep disorder management.

Chronic Pain Diagnosis Using Machine Learning, Questionnaires, and QST: A Sensitivity Experiment

In the last decade, machine learning has been widely used in different fields, especially because of its capacity to work with complex data. With the support of machine learning techniques, different studies have been using data-driven approaches to better understand some syndromes like mild cognitive impairment, Alzheimer’s disease, schizophrenia, and chronic pain. Chronic pain is a complex disease that can recurrently be misdiagnosed due to its comorbidities with other syndromes with which it shares symptoms. Within that context, several studies have been suggesting different machine learning algorithms to classify or predict chronic pain conditions. Those algorithms were fed with a diversity of data types, from self-report data based on questionnaires to the most advanced brain imaging techniques. In this study, we assessed the sensitivity of different algorithms and datasets classifying chronic pain syndromes. Together with this assessment, we highlighted important methodological steps that should be taken into account when an experiment using machine learning is conducted. The best results were obtained by ensemble-based algorithms and the dataset containing the greatest diversity of information, resulting in area under the receiver operating curve (AUC) values of around 0.85. In addition, the performance of the algorithms is strongly related to the hyper-parameters. Thus, a good strategy for hyper-parameter optimization should be used to extract the most from the algorithm. These findings support the notion that machine learning can be a powerful tool to better understand chronic pain conditions.

Fluoroscopic Epidural Steroid Injection: Pain Relief in Discogenic Sciatica Versus Lumbar Spinal Stenosis. A Study on Middle Eastern Patients

OBJECTIVE

To compare the effect of epidural steroid injections (ESI) in patients with discogenic sciatica (Sci) versus patients with lumbar canal stenosis (LSS), not controlled by conservative treatment.

MATERIALS AND METHODS

In our study, 80 patients with Sci and 66 with LSS were included. A single ESI (10 mg dexamethasone in 3 cc 0.25% bupivacaine) was applied under fluoroscopic control: one level above the highest stenotic level, in the posterior epidural space, via interlaminar approach in LSS and at the prolapse level, in the anterior epidural space, via transforaminal route in Sci. Pain intensity was assessed by VAS at baseline and on days 1, 15 and 30 after intervention.

RESULTS

The procedure was successful in 78 Sci and 63 LSS patients. Patients with Sci responded significantly better. At one month, pain reduction over 50% was achieved in 63% (52.3-73.7% at p = 0.95) of Sci but only in 35% (23.2-46.8%) of LSS (p = 0.03). Return to pre-intervention level happened in 47% (34.7-59.3%) of LSS versus 14% (6.3-21.7%) of Sci patients (p = 0.01). In 5 patients the procedure failed, without resulting morbidity.

CONCLUSION

ESI are more effective in patients with Sci than in single level LSS. In multiple level LSS, results are disappointing.

Effect of Caudal Traction on Mechanical Nociceptive Thresholds of Epaxial and Pelvic Musculature on a Group of Horses With Signs of Back Pain

Direct muscular attachment from lumbar vertebrae to the caudal vertebrae of the tail suggests that caudal traction, also described as a tail pull, may affect lumbar vertebral segments and/or associated soft tissues in horses. Traction is a commonly used human manual therapy technique used for pain relief and anecdotally observed to relieve pain in horses. However, research is lacking validating the efficacy of manual caudal traction on the horse. The objective of this study was to determine if caudal traction has an effect on mechanical nociceptive thresholds (MNTs) in a group of horses with clinical signs of back pain. Pressure algometry was used to measure MNTs of five bilateral anatomical sites in the epaxial and pelvic musculature of 11 horses referred to physiotherapy because of clinical signs of back pain. Measurements were recorded both before and immediately after traction. A significant difference (P ≤ .05) was identified between mean before and after caudal traction algometry measurements in all described sites. The percentage of MNT increase was highest in the thoracic region (83%) compared with the lumbar (50%) and the pelvic (52.4%) regions. These results support an effect of caudal traction in increasing MNTs in the thoracolumbar and pelvic regions in horses. Further research to determine the clinical effect of this technique is warranted.

Long-Lasting Anti-Inflammatory and Antinociceptive Effects of Acute Ammonium Glycyrrhizinate Administration: Pharmacological, Biochemical, and Docking Studies

The object of the study was to estimate the long-lasting effects induced by ammonium glycyrrhizinate (AG) after a single administration in mice using animal models of pain and inflammation together with biochemical and docking studies. A single intraperitoneal injection of AG was able to produce anti-inflammatory effects in zymosan-induced paw edema and peritonitis. Moreover, in several animal models of pain, such as the writhing test, the formalin test, and hyperalgesia induced by zymosan, AG administered 24 h before the tests was able to induce a strong antinociceptive effect. Molecular docking studies revealed that AG possesses higher affinity for microsomal prostaglandin E synthase type-2 compared to type-1, whereas it seems to locate better in the binding pocket of cyclooxygenase (COX)-2 compared to COX-1. These results demonstrated that AG induced anti-inflammatory and antinociceptive effects until 24-48 h after a single administration thanks to its ability to bind the COX/mPGEs pathway. Taken together, all these findings highlight the potential use of AG for clinical treatment of pain and/or inflammatory-related diseases.

Incidence and risk factors for development of persistent postsurgical pain following total knee arthroplasty: A retrospective cohort study

Persistent postsurgical pain (PPP) is defined as the discomfort that lasts >3 months postoperatively. The primary aim of this retrospective study was to estimate the risk of developing moderate-to-severe PPP after primary total knee arthroplasty (TKA). The secondary goal was to explore potential predictors of this outcome.Data were collected via hospital arthroplasty registry and chart review. The risk of moderate-to-severe PPP, defined as ≥4 on the numerical rating scale (NRS) at minimum of 3 months post-surgery, was calculated. Multivariable logistic regression was used to estimate the association of patient demographics, diagnoses, length of hospital stay, and preoperative NRS with the odds of developing PPP. Exploratory, simple logistic regression was used to estimate the association of perioperative factors with the odds of developing PPP on a subset of patients (n = 72).The risk of PPP after TKA was 31.3% (95% confidence interval [CI]: 27.5-35.0) (n = 578). Every 2-point increase in baseline NRS was associated with 1.66 (95% CI: 1.37-2.03) times the odds of developing PPP (P < .001). African-Americans (vs whites) had 1.82 (95% CI: 1.03-3.22) times the odds of developing PPP (P = .040). Exploratory analysis suggested that the adductor canal saphenous nerve (vs femoral nerve) blocks were associated with 2.87 (95% CI: 1.00-8.26) times the odds of developing PPP (P = .049).This study estimated a high risk (31.3%) of moderate-to-severe PPP after primary TKA. This study suggested that higher preoperative pain scores might be associated with greater odds of developing PPP. Moreover, this study suggested the possibility that racial differences and types of peripheral nerve blocks might be associated with greater odds of developing moderate-to-severe PPP after TKA surgery. However, the evidence obtained from our exploratory analysis of limited data certainly requires further exploration in large-scale studies.