Opioid Abuse in Chronic Pain--Misconceptions and Mitigation Strategies

Prevalence and correlates of prescription opioid use among US adults, 2019-2020

This study estimates the prevalence of prescription opioid use (POU) in the United States (US) in 2019-2020, both in the general population and specifically among adults with pain. It also identifies key geographic, demographic, and socioeconomic correlates of POU. Data were from the nationally-representative National Health Interview Survey 2019 and 2020 (N = 52,617). We estimated POU prevalence in the prior 12 months among all adults (18+), adults with chronic pain (CP), and adults with high-impact chronic pain (HICP). Modified Poisson regression models estimated POU patterns across covariates. We found POU prevalence of 11.9% (95% CI 11.5, 12.3) in the general population, 29.3% (95% CI 28.2, 30.4) among those with CP, and 41.2% (95% CI 39.2, 43.2) among those with HICP. Findings from fully-adjusted models include the following: In the general population, POU prevalence declined about 9% from 2019 to 2020 (PR = 0.91, 95% CI 0.85, 0.96). POU varied substantially across US geographic regions: It was significantly more common in the Midwest, West, and especially the South, where adults had 40% higher POU (PR = 1.40, 95% CI 1.26, 1.55) than in the Northeast. In contrast, there were no differences by rural/urban residence. In terms of individual characteristics, POU was lowest among immigrants and among the uninsured, and was highest among adults who were food insecure and/or not employed. These findings suggest that prescription opioid use remains high among American adults, especially those with pain. Geographic patterns suggest systemic differences in therapeutic regimes across regions but not rurality, while patterns across social characteristics highlight the complex, opposing effects of limited access to care and socioeconomic precarity. Against the backdrop of continuing debates about benefits and risks of opioid analgesics, this study identifies and invites further research about geographic regions and social groups with particularly high or low prescription opioid use.

A deep learning method to detect opioid prescription and opioid use disorder from electronic health records

OBJECTIVE

As the opioid epidemic continues across the United States, methods are needed to accurately and quickly identify patients at risk for opioid use disorder (OUD). The purpose of this study is to develop two predictive algorithms: one to predict opioid prescription and one to predict OUD.

MATERIALS AND METHODS

We developed an informatics algorithm that trains two deep learning models over patient Electronic Health Records (EHRs) using the MIMIC-III database. We utilize both the structured and unstructured parts of the EHR and show that it is possible to predict both challenging outcomes.

RESULTS

Our deep learning models incorporate elements from EHRs to predict opioid prescription with an F1-score of 0.88 ± 0.003 and an AUC-ROC of 0.93 ± 0.002. We also constructed a model to predict OUD diagnosis achieving an F1-score of 0.82 ± 0.05 and AUC-ROC of 0.94 ± 0.008.

DISCUSSION

Our model for OUD prediction outperformed prior algorithms for specificity, F1 score and AUC-ROC while achieving equivalent sensitivity. This demonstrates the importance of a) deep learning approaches in predicting OUD and b) incorporating both structured and unstructured data for this prediction task. No prediction models for opioid prescription as an outcome were found in the literature and therefore our model is the first to predict opioid prescribing behavior.

CONCLUSION

Algorithms such as those described in this paper will become increasingly important to understand the drivers underlying this national epidemic.

Assessing Opioid Abuse in Chronic Pain Patients: Further Validation of the Prescription Opioid Misuse Index (POMI) Using Item Response Theory

Due the limitations of the previous validations, the purpose of this study was to further validate the Prescription Opioid Misuse Index (POMI) in a larger sample of chronic non-cancer pain (CNCP) patients and to examine differential item functioning (DIF) across sex. Participants (n=225 CNCP patients under long-term opioid therapy) completed patient characteristics, self-reported POMI and DSM-5 prescription opioid use disorder measurements. Reliability and factor structure were assessed using both item response theory and classical test theory. ROC curve analysis was used to establish the optimum cut-off score for detecting the presence of DSM-5 prescription opioid-use disorder. Concurrent validity was also tested. The POMI showed a unidimensional factor structure and acceptable internal consistency (ωcat =0.62). DIF analysis showed that males and females respond similarly to each item of the POMI, supporting unbiased measurement of the latent trait across both groups. A cut-off point of 2 is suggested in order to maximize the accuracy of the instrument as a first-screening tool for opioid misuse (AUC=0.78; p<0.001; CI 95%: 0.72–0.85). Concurrent validity of the POMI was high with DSM-5 moderate to severe opioid-use disorder criteria (OR=7.824, p<0.001). These results indicate that the POMI is a valid and clinically feasible screening instrument for detecting CNCP patients who misuse opioid medications. The short length of the scale could meet the needs of clinical practice as it allows clinicians to precisely identify and monitor prescription opioid misuse in both male and female patients.

We need to talk: The urgent conversation on chronic pain, mental health, prescribing patterns and the opioid crisis

The opioid crisis’ pathways from first exposure onwards to eventual illnesses and fatalities are multiple, intertwined and difficult to dissect. Here, we offer a multidisciplinary appraisal of the relationships among mental health, chronic pain, prescribing patterns worldwide and the opioid crisis. Because the opioid crisis’ toll is especially harsh on young people, emphasis is given on data regarding the younger strata of the population. Because analgesic opioid prescription constitute a recognised entry point towards misuse, opioid use disorder, and ultimately overdose, prescribing patterns across different countries are examined as a modifiable hazard factor along these pathways of risk. Psychiatrists are called to play a more compelling role in this urgent conversation, as they are uniquely placed to provide synthesis and lead action among the different fields of knowledge and care that lie at the crossroads of the opioid crisis. Psychiatrists are also ideally positioned to gauge and disseminate the foundations for diagnosis and clinical management of mental conditions associated with chronic pain, including the identification of hazardous and protective factors. It is our hope to spark more interdisciplinary exchanges and encourage psychiatrists worldwide to become leaders in an urgent conversation with interlocutors from the clinical and basic sciences, policy makers and stakeholders including clients and their families.

Mechanisms of Transmission and Processing of Pain: A Narrative Review

Knowledge about the mechanisms of transmission and the processing of nociceptive information, both in healthy and pathological states, has greatly expanded in recent years. This rapid progress is due to a multidisciplinary approach involving the simultaneous use of different branches of study, such as systems neurobiology, behavioral analysis, genetics, and cell and molecular techniques. This narrative review aims to clarify the mechanisms of transmission and the processing of pain while also taking into account the characteristics and properties of nociceptors and how the immune system influences pain perception. Moreover, several important aspects of this crucial theme of human life will be discussed. Nociceptor neurons and the immune system play a key role in pain and inflammation. The interactions between the immune system and nociceptors occur within peripheral sites of injury and the central nervous system. The modulation of nociceptor activity or chemical mediators may provide promising novel approaches to the treatment of pain and chronic inflammatory disease. The sensory nervous system is fundamental in the modulation of the host's protective response, and understanding its interactions is pivotal in the process of revealing new strategies for the treatment of pain.

Effect of intrathecal NIS-lncRNA antisense oligonucleotides on neuropathic pain caused by nerve trauma, chemotherapy, or diabetes mellitus

BACKGROUND

Blocking increased expression of nerve injury-specific long non-coding RNA (NIS-lncRNA) in injured dorsal root ganglia (DRG) through DRG microinjection of NIS-lncRNA small hairpin interfering RNA or generation of NIS-lncRNA knockdown mice mitigates neuropathic pain. However, these strategies are impractical in the clinic. This study employed a Food and Drug Administration (FDA)-approved antisense oligonucleotides strategy to examine the effect of NIS-lncRNA ASOs on neuropathic pain.

METHODS

Effects of intrathecal injection of NIS-lncRNA antisense oligonucleotides on day 7 or 14 after chronic constriction injury (CCI) of the sciatic nerve, fourth lumbar (L4) spinal nerve ligation, or intraperitoneal injection of paclitaxel or streptozotocin on the expression of DRG NIS-lncRNA and C-C chemokine ligand 2 (CCL2, an NIS-lncRNA downstream target) and nociceptive hypersensitivity were examined. We also assessed whether NIS-lncRNA antisense oligonucleotides produced cellular toxicity.

RESULTS

Intrathecal NIS-lncRNA antisense oligonucleotides attenuated CCI-induced mechanical allodynia, heat hyperalgesia, cold hyperalgesia, and ongoing nociceptive responses, without changing basal or acute nociceptive responses and locomotor function. Intrathecal NIS-lncRNA antisense oligonucleotides also blocked CCI-induced increases in NIS-lncRNA and CCL2 in the ipsilateral L3 and L4 DRG and hyperactivities of neurones and astrocytes in the ipsilateral L3 and L4 spinal cord dorsal horn. Similar results were found in antisense oligonucleotides-treated mice after spinal nerve ligation or intraperitoneal injection of paclitaxel or streptozotocin. Normal morphologic structure and no cell loss were observed in the DRG and spinal cord of antisense oligonucleotides-treated mice.

CONCLUSION

These findings further validate the role of NIS-lncRNA in trauma-, chemotherapy-, or diabetes-induced neuropathic pain and demonstrate potential clinical application of NIS-lncRNA antisense oligonucleotides for neuropathic pain management.

A Pharmacological Review of Calcitonin Gene-Related Peptide Biologics and Future Use for Chronic Pain

Calcitonin gene-related peptide (CGRP) antagonist medications have become the mainstay of acute and chronic migraine management in the outpatient setting and look to become more widely utilized by clinicians once the medications become available in generic form. However, their role in practice has remained limited to the treatment of migraines despite the ubiquitous presence of the molecule throughout the body. The literature surrounding expansion of the utility of these medications is limited; however, there have been several promising publications, and further studies are in the process to quantify their utility in the treatment of other pain-related disorders. This is a qualitative review of the current literature surrounding CGRP, particularly in relation to the treatment of non-migraine pain conditions, and looks to suggest potential utility in the field of chronic pain.

Functional consequences of short-term exposure to opioids versus cannabinoids in nonhuman primates

Opioids provide pain relief but are associated with several adverse effects. Researchers are exploring cannabis-based medicine as an alternative. However, little is known about the tendency for physical dependence on cannabinoids in comparison with that on opioids in primates. The aim of this study was to compare the potency of heroin and delta-9-tetrahydrocannabinol (THC) in eliciting analgesic effects and the development of physical dependence between opioids and cannabinoids in both male and female rhesus monkeys. Systemic administration of either heroin (0.03-0.18 mg/kg) or THC (0.3-1.8 mg/kg) in a dose-dependent manner produced antinociceptive effects against an acute thermal nociceptive stimulus. The μ-opioid receptor antagonist naltrexone (0.01 mg/kg) and the cannabinoid receptor antagonist SR141716A (0.3 mg/kg) produced the same degree of rightward shift in the dose-response curves for heroin- and THC-induced antinociception, respectively. Monkeys implanted with telemetry devices were subjected to short-term repeated administrations (two injections per day for 1-3 days) of either heroin (0.18 mg/kg), morphine (1.8 mg/kg), THC (1.8 mg/kg), or CP 55,940 (0.032 mg/kg). Administration of naltrexone (0.01 mg/kg) increased respiration, heart rate, and blood pressure in heroin- or morphine-treated monkeys. In contrast, administration of SR141716A (0.3 mg/kg) did not cause a significant change in these physiological parameters in THC- or CP 55,940-treated monkeys. Additionally, morphine, but not CP 55,940, enhanced the monkeys' hypersensitivity to the algogen capsaicin. Collectively, these results demonstrate that in nonhuman primates, both opioids and cannabinoids exert comparable antinociception; however, physical dependence on opioids, but not cannabinoids, at their antinociceptive doses, occurs following short-term exposures.

Opioid Use Among Social Security Disability Insurance Applicants, 2013–2018

Opioid use is common among Social Security Disability Insurance (SSDI) beneficiaries who account for a disproportionate share of opioid-related hospitalizations and mortality. However, little is known about the prevalence of opioid use prior to SSDI enrollment. Understanding when opioid use is established and how it correlates with individual characteristics and community prescribing practices would inform policy approaches to reducing opioid-related harms among SSDI beneficiaries. We estimated the prevalence of opioid use among SSDI applicants by applying a natural language processing algorithm to SSDI application data. We find the prevalence of opioid use among SSDI applicants declined from 33% in 2013 to 24% in 2018. In contrast, the share of applicants with musculoskeletal impairments, which are commonly associated with pain, was unchanged. The share of applications reporting opioid use declined across both sexes, all age groups and education levels, and all regions. There was substantial variation, however, in the magnitude of decline by geography, with the smallest declines in parts of the Midwest and Southeastern United States. SSDI application rates and applications reporting opioid use were more likely to come from communities with higher opioid prescribing rates. Our estimates suggest most SSDI beneficiaries began opioid use prior to entering the SSDI program.

Noncoding RNAs: Novel Targets for Opioid Tolerance

As a global health problem, chronic pain is one of the leading causes of disability, and it imposes a huge economic and public health burden on families and society. Opioids represent the cornerstone of analgesic drugs. However, opioid tolerance caused by long-term application of opioids is a major factor leading to drug withdrawal, serious side effects caused by dose increases, and even the death of patients, placing an increasing burden on individuals, medicine, and society. Despite efforts to develop methods to prevent and treat opioid tolerance, no effective treatment has yet been found. Therefore, understanding the mechanism underlying opioid tolerance is crucial for finding new prevention and treatment strategies. Noncoding RNAs (ncRNAs) are important parts of mammalian gene transcriptomes, and there are thousands of unique noncoding RNA sequences in cells. With the rapid development of high-throughput genome technology, research on ncRNAs has become a hot topic in biomedical research. In recent years, studies have shown that ncRNAs mediate physiological and pathological processes, including chromatin remodeling, transcription, posttranscriptional modification and signal transduction, which are key regulators of physiological processes in developmental and disease environments and have become biomarkers and potential therapeutic targets for various diseases. An increasing number of studies have found that ncRNAs are closely related to the development of opioid tolerance. In this review, we have summarized the evidence that ncRNAs play an important role in opioid tolerance and that ncRNAs may be novel targets for opioid tolerance.

Chronic scrotal content pain: the experiences of patients undergoing microsurgical spermatic cord denervation

Background

Chronic scrotal content pain, sometimes referred to as chronic orchialgia, is a common urological condition that gives rise to persistent and often severe painful stimuli to the scrotum and surrounding structures. Despite its relative commonality, accounting for over 2% of urological visits, chronic scrotal content pain is complex to manage and patients may be required to access multiple providers and undergo invasive procedures, including microsurgical spermatic cord denervation (MSCD) surgery.

Objective

The objective of this study was to understand the experiences and perspectives of persons with chronic scrotal content pain and accessing MSCD surgery.

Design

An exploratory qualitative design, guided by interpretive description and integrated knowledge translation, was adopted.

Methods

We conducted in-depth qualitative interviews with six patients with chronic scrotal content pain who underwent MSCD surgery in a surgical center in Western Canada. Data were analyzed thematically.

Results

Analysis of the study data resulted in three core themes: living with chronic scrotal content pain, quality of life, and MSCD procedure and outcomes. We highlight the debilitating nature of pain and the broad impacts upon health, quality of life, and social functioning. Participants described how MSCD surgery offered an effective solution for persistent and debilitating pain. For the participants, MSCD surgery offered hope and the chance to regain their normality.

Conclusion

For those with chronic scrotal content pain, access to a pain specialist, along with the adoption of a biopsychosocial approach to pain and early access to MSCD surgery, may improve patient experiences and outcomes. Considering the high prevalence of urological pain, greater interdisciplinary care is needed in order to support more effective and timely management.

Adolescent anxiety and pain problems: A joint, genome-wide investigation and pathway-based analysis

Both common pain and anxiety problems are widespread, debilitating and often begin in childhood-adolescence. Twin studies indicate that this co-occurrence is likely due to shared elements of risk, rather than reciprocal causation. A joint genome-wide investigation and pathway/network-based analysis of adolescent anxiety and pain problems can identify genetic pathways that subserve shared etiopathogenetic mechanisms. Pathway-based analyses were performed in the independent samples of: The Quebec Newborn Twin Study (QNTS; 246 twin pairs and 321 parents), the Longitudinal Study of Child Development in Quebec (QLSCD; n = 754), and in the combined QNTS and QLSCD sample. Multiple suggestive associations (p<1×10-5), and several enriched pathways were found after FDR correction for both phenotypes in the QNTS; many nominally-significant enriched pathways overlapped between pain problems and anxiety symptoms (uncorrected p<0.05) and yielded results consistent with previous studies of pain or anxiety. The QLSCD and the combined QNTS and QLSCD sample yielded similar findings. We replicated an association between the pathway involved in the regulation of myotube differentiation (GO:0010830) and both pain and anxiety problems in the QLSDC and the combined QNTS and QLSCD sample. Although limited by sample size and thus power, these data provide an initial support to conjoint molecular investigations of adolescent pain and anxiety problems. Understanding the etiology underlying pain and anxiety co-occurrence in this age range is relevant to address the nature of comorbidity and its developmental pathways, and shape intervention. The replication across samples implies that these effects are reliable and possess external validity.

The State of the Research on Opioid Outcomes Among Lesbian, Gay, Bisexual, Transgender, Queer, and Other Sexuality- and Gender-Diverse Populations: A Scoping Review

Purpose: Research on opioid misuse, opioid use disorder (OUD), and overdose (i.e., opioid outcomes) among lesbian, gay, bisexual, transgender, queer, and other populations within the LGBTQ umbrella (LGBTQ+) remains sparse. The purpose of this scoping review was to characterize the state of the research on opioid outcomes among LGBTQ+ populations, and identify gaps in the extant literature and areas for future research. Methods: We conducted a scoping review of peer-reviewed, English language articles published between 2011 and 2020 that examined opioid outcomes among LGBTQ+ populations in the CINAHL, Embase, PubMed, and PsycINFO databases. We extracted data from articles that focused on opioid outcomes within their specific aims or purpose. We include a general summary for articles that secondarily described opioid outcomes among LGBTQ+ populations. Results: Of 113 published studies that examined opioid outcomes among LGBTQ+ populations, 10% (n = 11) were specifically designed to focus on this topic. Across studies, bisexual populations, particularly women, were at highest risk for opioid misuse and OUD. Few studies examined opioid outcomes by more than one dimension of sexual orientation (n = 3, 27%), race and/or ethnicity (n = 3, 27%), or age (n = 5, 45%). Only two included transgender or gender diverse samples; only one explicitly measured gender identity. Conclusions: Future research is needed to understand the impact of the opioid epidemic on LGBTQ+ people, particularly transgender and other gender diverse individuals, and the intersectional role of race, ethnicity, and age in opioid disparities among LGBTQ+ individuals. Additional research could contribute to the development of much-needed affirming OUD treatment and other services for LGBTQ+ people.

Healthcare provider knowledge, beliefs, and attitudes regarding opioids for chronic non-cancer pain in North America prior to the emergence of COVID-19: A systematic review of qualitative research

Background

Balance between benefits and harms of using opioids for the management of chronic noncancer pain (CNCP) must be carefully considered on a case-by-case basis. There is no one-size-fits-all approach that can be executed by prescribers and clinicians when considering this therapy.

Aim

The aim of this study was to identify barriers and facilitators for prescribing opioids for CNCP through a systematic review of qualitative literature.

Methods

Six databases were searched from inception to June 2019 for qualitative studies reporting on provider knowledge, attitudes, beliefs, or practices pertaining to prescribing opioids for CNCP in North America. Data were extracted, risk of bias was rated, and confidence in evidence was graded.

Results

Twenty-seven studies reporting data from 599 health care providers were included. Ten themes emerged that influenced clinical decision making when prescribing opioids. Providers were more comfortable to prescribe opioids when (1) patients were actively engaged in pain self-management, (2) clear institutional prescribing policies were present and prescription drug monitoring programs were used, (3) long-standing relationships and strong therapeutic alliance were present, and (4) interprofessional supports were available. Factors that reduced likelihood of prescribing opioids included (1) uncertainty toward subjectivity of pain and efficacy of opioids, (2) concern for the patient (e.g., adverse effects) and community (i.e., diversion), (3) previous negative experiences (e.g., receiving threats), (4) difficulty enacting guidelines, and (5) organizational barriers (e.g., insufficient appointment duration and lengthy documentation).

Conclusions

Understanding barriers and facilitators that influence opioid-prescribing practices offers insight into modifiable targets for interventions that can support providers in delivering care consistent with practice guidelines.

The Association of Opioid Misuse and Suicidality among People with Disabilities

Background/Purpose: Past research has linked non-medical prescription opioid use (NMPOU) with suicide, though less focus has been placed among people with disabilities impacted by the opioid epidemic. This study examined the relationship of NMPOU and suicidality among people with and without disabilities while controlling for sociodemographic and other variables. Method: Using the 2019 National Survey on Drug Use and Health, weighted logistic regression analyses were conducted on a cross-sectional sample of 38,088 respondents 18 and older to examine the effect of opioid misuse and disability on serious thoughts of suicide, having a suicide plan, and making a suicide attempt. Results: Findings indicated opioid misuse was associated with 37% higher odds for having a suicide plan in the past year (OR = 1.37, p < .05). The main results indicated the people with disabilities had 30% higher odds for having a suicide plan (OR = 1.30, p < .05) and 73% higher odds for a suicide attempt in the past year (OR = 1.73, p < .001). Interaction analysis found that opioid misuse was associated with higher odds for having a suicide plan (OR = 1.89, p < .01), and having a suicide attempt among those with disabilities (OR = 2.57, p < .01). Conclusion: Results indicated that opioid misuse is a risk factor for suicide, and people with disabilities were at greater risk. Health workers can serve as a nexus point in effectively engaging at-risk people with disabilities in substance use and mental health prevention and recovery services.

Total knee arthroplasty is associated with greater immediate post-surgical pain and opioid use than total hip arthroplasty

BACKGROUND

As greater emphasis is being placed on opioid reduction strategies and implementation of multimodal analgesia, we sought to determine whether immediate post-surgical opioid consumption was different between THA and TKA.

METHODS

A single-institution total joint arthroplasty database was used to identify patients who underwent elective THA and TKA from 2016 to July 2019. Baseline demographic data, operative time (defined by incision time), and American Society of Anesthesiologist (ASA) class were collected. Morphine milligram equivalents (MME) were calculated and derived from prospectively documented nursing opioid administration events, while visual analog scale (VAS) scores represented pain levels, both of which were collected as part of our institution's standard protocols. Activity Measure for Post-Acute Care (AMPAC) was used to determine physical therapy progress.

RESULTS

A total of 11,693 cases were identified: 5,909 THA (50.53%) and 5784 (49.47%) TKA. THA patients tended to be slightly younger (63.38 years, SD 11.61 years, vs 65.72 years, SD 9.56 years; p < 0.01) and have lower BMIs (28.92 kg/m² vs 32.52 kg/m²; p < 0.01). THA patients had lower ASA scores in comparison to TKA patients (p < 0.01). Aggregate opioid consumption (93.76 MME vs 147.55 MME; p < 0.01) along with first 24-h and 48-h usage was significantly less for THA as compared to TKA. Similarly, mean pain scores (4.15 vs 5.08; p < 0.01) were lower for THA, while AMPAC mobilization scores were higher (20.88 vs 19.29; p < 0.01) when compared to TKA.

CONCLUSION

THA patients reported lower pain scores and were found to require less opioid medication in the immediate post-surgical period than TKA patients.

Sex differences in associations between delay discounting and expectancies for alcohol analgesia

Self-medication of pain with alcohol is prevalent, and expectancies for alcohol analgesia likely influence pain relief and alcohol consumption. Hazardous alcohol use has been associated with greater delay discounting rates; however, little is known about the relationship between delay discounting and expectancies for alcohol analgesia. Therefore, the present study examined sex differences in associations between delay discounting and expectancies for alcohol analgesia. Healthy drinkers without chronic pain (N = 53) completed measures of expectancies for alcohol analgesia, alcohol use, and alcohol outcome expectancies. A five-trial adjusting-delay discounting task (DDT) for monetary outcomes was also administered. Regression analyses revealed that sex moderated the relationship between delay discounting and expectancies for alcohol analgesia. Steeper delay discounting rates were associated with weaker expectancies for alcohol analgesia among men when adjusting for average alcohol consumption. Among women, nonsignificant associations between delay discounting rates and expectancies for alcohol analgesia were observed. These findings provide initial evidence of sex differences in associations between delay discounting and expectancies for alcohol analgesia. The directionality of these associations was unexpected and may have implications for patterns of self-medication with alcohol. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Exploring pharmacological inhibition of Gq/11 as an analgesic strategy

BACKGROUND AND PURPOSE

Misuse of opioids has greatly affected our society. One potential solution is to develop analgesics that act at targets other than opioid receptors. These can be used either as stand-alone therapeutics or to improve the safety profile of opioid drugs. Previous research showed that activation of G_q/11 proteins by G-protein coupled receptors has pro-nociceptive properties, suggesting that blockade of G_q/11 signalling could be beneficial for pain control. The aim of this study was to test this hypothesis pharmacologically by using potent and selective G_q/11 inhibitor YM-254890.

EXPERIMENTAL APPROACH

We used a series of behavioural assays to evaluate the acute responses of mice to painful thermal stimulation while administering YM-254890 alone and in combination with morphine. We then used electrophysiological recordings to evaluate the effects of YM-254890 on the excitability of dorsal root ganglion (DRG) nociceptor neurons.

KEY RESULTS

We found that systemic administration of YM-254890 produced anti-nociceptive effects and also augmented morphine analgesia in both hotplate and tail flick paradigms. However, it also caused substantial inhibition of locomotion, which may limit its therapeutic utility. To circumvent these issues, we explored the local administration of YM-254890. Intrathecal injections of YM-254890 produced lasting analgesia in a tail flick test and greatly augmented the anti-nociceptive effects of morphine without any significant effects on locomotor behaviour. Electrophysiological studies showed that YM-254890 reduced the excitability of DRG nociceptors and augmented their opioid-induced inhibition.

CONCLUSION AND IMPLICATIONS

These findings indicate that pharmacological inhibition of G_q/11 could be explored as an analgesic strategy.

Clinical trials and promising preclinical applications of CRISPR/Cas gene editing

Treatment of genetic disorders by genomic manipulation has been the unreachable goal of researchers for many decades. Although our understanding of the genetic basis of genetic diseases has advanced tremendously in the last few decades, the tools developed for genomic editing were not efficient and practical for their use in the clinical setting until now. The recent advancements in the research of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein (Cas) systems offered an easy and efficient way to edit the genome and accelerated the research on their potential use in the treatment of genetic disorders. In this review, we summarize the clinical trials that evaluate the CRISPR/Cas systems for treating different genetic diseases and highlight promising preclinical research on CRISPR/Cas mediated treatment of a great diversity of genetic disorders. Ultimately, we discuss the future of CRISPR/Cas mediated genome editing in genetic diseases.

Bibliometric and visual analysis of research on the links between the gut microbiota and pain from 2002 to 2021

BACKGROUND AND AIMS

The gut microbiota is involved in the regulation of pain, which is proved by plenty of evidence. Although a substantial quantity of research on the link between the gut microbiota and pain has emerged, no study has focused on the bibliometric analysis of this topic. We aim to present a bibliometric review of publications over the past 20 years and predict research hot spots.

METHODS

Relevant publications between 2002 and 2021 were extracted from the Science Citation Index-Expanded (SCI-EXPANDED) of the Web of Science Core Collection (WoSCC) database on April 22, 2022. CiteSpace (version 5.8 R3c), VOSviewer, the Online Analysis Platform of Literature Metrology, and the R package bibliometrix were used to analyze and visualize.

RESULTS

A total of 233 articles have been published between 2002 and 2021. The number of publication outputs increased rapidly since 2016. The collaboration network revealed that the USA, Baylor College of Medicine, and Vassilia Theodorou were the most influential country, institute, and scholar, respectively. Alimentary pharmacology and therapeutics and Gut were the most co-cited journal and Neurogastroenterology and Motility was the most productive journal. Visceral sensitivity, fibromyalgia, gastrointestinal, chronic pain, stress, gut microbiome, LGG, brain-gut axis, SLAB51, and sequencing were the top 10 clusters in co-occurrence cluster analysis. Keyword burst detection indicated that the brain-gut axis and short-chain fatty acid were the current research hot spots.

CONCLUSION

Research on the links between the gut microbiota and pain has increased rapidly since 2016. The current research focused on the brain-gut axis and short-chain fatty acid. Accordingly, the SCFAs-mediated mechanism of pain regulation will be a research direction of great importance on the links between the gut microbiota and pain. This study provided instructive assistance to direct future research efforts on the links between the gut microbiota and pain.

The efficacy of sensory neural entrainment on acute and chronic pain: A systematic review and meta-analysis

Background

Changes to the power of neural oscillations in cortical and sub-cortical structures can change pain perception. Rhythmic sensory stimulation is a non-invasive method that can increase power in specific frequencies of neural oscillations. If the stimulation frequency targets those frequencies related to pain perception, such as alpha or theta frequencies, there can be a reduction in perceived pain intensity. Thus, sensory neural entrainment may provide an alternative to pharmacological intervention for acute and chronic pain. This review aimed to identify and critically appraise the evidence on the effectiveness of sensory entrainment methods for pain perception.

Methods

We undertook a systematic search across Medline, Embase, PsycInfo, Web of Science and Scopus in November 2020 to identify studies investigating the efficacy of sensory entrainment on adults. We assessed studies for their quality using the PRISMA checklist. A random-effects model was used in a meta-analysis to measure the effect of entrainment on pain perception.

Results

Our systematic review yielded nine studies fitting the search criteria. Studies investigated the effect of visual and auditory entrainment on pain intensity rating, electrophysiological markers of pain and amount of analgesia needed during surgery. The meta-analysis suggests that alpha (8–13 Hz) sensory entrainment is effective for acute pain perception, whereas theta (4–7 Hz) entrainment is effective for chronic pain.

Conclusions

Although there is heterogeneity in the current evidence, our review highlights the potential use of sensory entrainment to affect acute and chronic pain. Further research is required regarding the timing, duration and frequency of the stimulation to determine the best application for maximum efficacy.

OFP011 Cyclic Peptide as a Multifunctional Agonist for Opioid/Neuropeptide FF Receptors with Improved Blood-Brain Barrier Penetration

Mounting evidence indicates that the neuropeptide FF (NPFF) system is involved in the side effects of opioid usage, including antinociceptive tolerance, hyperalgesia, abuse, constipation, and respiratory depression. Our group recently discovered that the multitarget opioid/NPFF receptor agonist DN-9 exhibits peripheral antinociceptive activity. To improve its metabolic stability, antinociceptive potency, and duration, in this study, we designed and synthesized a novel cyclic disulfide analogue of DN-9, OFP011, and examined its bioactivity through in vitro cyclic adenosine monophosphate (cAMP) functional assays and in vivo behavioral experiments. OFP011 exhibited multifunctional agonistic effects at the μ-opioid and the NPFF₁ and NPFF₂ receptors and partial agonistic effects at the δ- and κ-opioid in vitro, as determined via the cAMP functional assays. Pharmacokinetic and pharmacological experiments revealed improvement in its blood-brain barrier permeability after systemic administration. In addition, subcutaneous OFP011 exhibited potent and long-lasting antinociceptive activity via the central μ- and κ-opioid receptors, as observed in different physiological and pathological pain models. At the highest antinociceptive doses, subcutaneous OFP011 exhibited limited tolerance, gastrointestinal transit, motor coordination, addiction, reward, and respiration depression. Notably, OFP011 exhibited potent oral antinociceptive activities in mouse models of acute, inflammatory, and neuropathic pain. These results suggest that the multifunctional opioid/NPFF receptor agonists with improved blood-brain barrier penetration are a promising strategy for long-term treatment of moderate to severe nociceptive and pathological pain with fewer side effects.

Negative allosteric modulation of CB1 cannabinoid receptor signaling suppresses opioid-mediated reward

Blockade of cannabinoid type 1 (CB₁)-receptor signaling decreases the rewarding properties of many drugs of abuse and has been proposed as an anti-addiction strategy. However, psychiatric side-effects limit the clinical potential of orthosteric CB₁ antagonists. Negative allosteric modulators (NAMs) represent a novel and indirect approach to attenuate CB₁ signaling by decreasing affinity and/or efficacy of CB₁ ligands. We hypothesized that a CB₁-NAM would block opioid reward while avoiding the unwanted effects of orthosteric CB₁ antagonists. GAT358, a CB₁-NAM, failed to elicit cardinal signs of direct CB₁ activation or inactivation when administered by itself. GAT358 decreased catalepsy and hypothermia but not antinociception produced by the orthosteric CB₁ agonist CP55,940, suggesting that a CB₁-NAM blocked cardinal signs of CB₁ activation. Next, GAT358 was evaluated using in vivo assays of opioid-induced dopamine release and reward in male rodents. In the nucleus accumbens shell, a key component of the mesocorticolimbic reward pathway, morphine increased electrically-evoked dopamine efflux and this effect was blocked by a dose of GAT358 that lacked intrinsic effects on evoked dopamine efflux. Moreover, GAT358 blocked morphine-induced reward in a conditioned place preference (CPP) assay without producing reward or aversion alone. GAT358-induced blockade of morphine CPP was also occluded by GAT229, a CB₁ positive allosteric modulator (CB₁-PAM), and absent in CB₁-knockout mice. Finally, GAT358 also reduced oral oxycodone (but not water) consumption in a two-bottle choice paradigm. Our results support the therapeutic potential of CB₁-NAMs as novel drug candidates aimed at preventing opioid reward and treating opioid abuse while avoiding unwanted side-effects.

Reward drive moderates the effect of depression-related cognitive mechanisms on risk of prescription opioid misuse among patients with chronic non-cancer pain

Depression, a prognostic factor for prescription opioid misuse commonly occurs in people with chronic non-cancer pain (CNCP). However, the mechanisms linking depression and prescription opioid misuse remain unclear. This study examined the potential mediating role of pain catastrophizing in the association between depressive symptoms and prescription opioid misuse risk, and impulsivity traits as possible moderators of these relationships. Individuals (N = 198; 77% women) with CNCP using prescription opioids participated in a cross-sectional online survey with validated measures of depression, pain catastrophizing, rash impulsiveness, reward drive, anxiety, pain severity and prescription opioid misuse. Meditation analyses with percentile-based bootstrapping examined pathways to prescription opioid use, controlling for age, sex, pain severity, and anxiety symptoms. Partial moderated mediation of the indirect effect of depressive symptoms on prescription opioid misuse risk through pain catastrophizing by rash impulsiveness and reward drive were estimated. Pain catastrophizing mediated depressive symptoms and prescription opioid misuse risk. Indirect effects were stronger when moderate to high levels of reward drive were included in the model. Findings suggest the risk of prescription opioid misuse in those experiencing depressive symptoms and pain catastrophizing is particularly higher for those higher in reward drive. Treatments targeting these mechanisms may reduce opioid misuse risk. PERSPECTIVE: This article identifies reward drive as a potentially important factor increasing the effects of depression-related cognitive mechanisms on risk of prescription opioid misuse in those with CNCP. These findings could assist in personalizing clinical CNCP management to reduce the risks associated with opioid misuse.

Pain sensitivity is modulated by affective temperament: Results from the population-based CHRIS Affective Disorder (CHRIS-AD) study

BACKGROUND

Nociceptive pain modulation is related to psychological and psychiatric conditions. Evidence from clinical studies backs innate temperaments as potential precursors of mood symptoms and disorders, and pain sensitivity. Our study examines the modulation effect of affective temperaments on pain sensitivity in a general population adult sample, accounting for possible intervening mood symptoms, lifetime anxiety and depression, and pain treatments.

METHODS

The sample is part of the CHRIS-AD study, Italy. Primary outcomes were the pain sensitivity questionnaire PSQ-total intensity score and the experimental pressure pain threshold (PPT). Affective temperaments were evaluated with the TEMPS-M. Lifetime depression, anxiety, current mood disorders, and treatments were self-reported via rating-scales. Directed acyclic graphs theory guided linear and mixed linear regression model analyses.

RESULTS

Among 3804 participants (aged 18-65; response rate 78.4 %, females 53.3 %, mean age 38.4 years) for any given temperament, both the PSQ-total and the PPT were associated with temperament. The TEMPS-M four cyclothymic-related temperaments aligned on the pain-sensitive pole and the hyperthymic on the pain-resilient pole. The inclusion of current or lifetime mood symptoms, or pain drug use, as possible intervening pathways only partly diluted these associations, with stronger evidence for an effect of trait anxiety.

LIMITATIONS

The main limitations were the lack of experimental measures of suprathreshold pain intensity perception, and detailed information on affective disorders in the study population.

CONCLUSIONS

These findings support the hypothesis of a biological dichotomous diathesis of affective temperaments towards pain sensitivity; hyperthymic suggesting protection, whereas cyclothymic suggesting predisposition.

A Comparison of Institutional Opioid Equianalgesia Tools: A National Study

Context: Equianalgesic tools are commonly utilized to guide dose of analgesic therapy, but there is no national consensus on equianalgesic calculations in the United States. Objectives: To propose a summary of current opioid equianalgesic data that include variations and trends among national institutions. Methods: Opioid equianalgesic tools were obtained between May and September 2021. For meperidine, tramadol, codeine, hydrocodone, morphine, oxycodone, oxymorphone, hydromorphone, levorphanol, fentanyl, and tapentadol, details of adjustment for incomplete tolerance, opioid equianalgesic ratios, and formulation types were collected and analyzed. Baseline opioid pharmaco kinetic data were obtained through manufacturer labels on FDA databases, including half-life (T1/2), volume of distribution (Vd), clearance (Cl), area under the curve (AUC), max concentration (Cmax), and time to max concentration (Tmax). Results: Thirty-two institutions' equianalgesic tools were included with each study opioid appearing on an average of 23 institutions' tools. Few tools contained guidance on levorphanol or tapentadol; or included minimum and maximum recommended doses. All tools included guidance on fentanyl, hydromorphone, oxycodone, morphine, and hydrocodone. A minority of tools included guidance on cross-tolerance considerations (n = 12, 37.5%). Oral-tramadol-to-oral-morphine and oral-hydromorphone-to-intravenous (IV)-hydromorphone had the largest variances across equianalgesic tools (6.7 ± 2.8 and 4.06 ± 1.2 mg, respectively). Conclusion: Opioid equianalgesia tools from across the United States demonstrated significant variation in their inclusion of guidance on adjustment for incomplete cross-tolerance, oral-to-IV, and oral-to-oral opioid equianalgesic ratios, and which opioids and formulations were listed. Tramadol and hydromorphone had the most variation in their equianalgesic guidance among the opioids.

Endogenous opioid systems alterations in pain and opioid use disorder

Decades of research advances have established a central role for endogenous opioid systems in regulating reward processing, mood, motivation, learning and memory, gastrointestinal function, and pain relief. Endogenous opioid systems are present ubiquitously throughout the central and peripheral nervous system. They are composed of four families, namely the μ (MOPR), κ (KOPR), δ (DOPR), and nociceptin/orphanin FQ (NOPR) opioid receptors systems. These receptors signal through the action of their endogenous opioid peptides β-endorphins, dynorphins, enkephalins, and nociceptins, respectfully, to maintain homeostasis under normal physiological states. Due to their prominent role in pain regulation, exogenous opioids-primarily targeting the MOPR, have been historically used in medicine as analgesics, but their ability to produce euphoric effects also present high risks for abuse. The ability of pain and opioid use to perturb endogenous opioid system function, particularly within the central nervous system, may increase the likelihood of developing opioid use disorder (OUD). Today, the opioid crisis represents a major social, economic, and public health concern. In this review, we summarize the current state of the literature on the function, expression, pharmacology, and regulation of endogenous opioid systems in pain. Additionally, we discuss the adaptations in the endogenous opioid systems upon use of exogenous opioids which contribute to the development of OUD. Finally, we describe the intricate relationship between pain, endogenous opioid systems, and the proclivity for opioid misuse, as well as potential advances in generating safer and more efficient pain therapies.

A model to understand antecedents of nursing attitudes and perceptions influencing outcomes of patients with SUD

INTRODUCTION

Substance use disorder (SUD) is a persistent and long-standing public health issue in the United States. While SUD is medically considered a chronic illness, it is also one that is viewed as self-inflicted, thereby resulting in judgmental attitudes and stigmatization from care providers, specifically from nurses.

DESIGN

In 2020, the authors completed an analytical cross-sectional study that included open-ended questions to examine nurses' knowledge and attitudes toward caring for patients with SUD across practice settings.

METHODS

A conceptual model was constructed by examining original study data and published literature on SUD, re-analyzing themes, determining constructs and variables, then coming to a consensus on critical aspects of the model.

CONCLUSION

The resulting conceptual model highlights antecedents of nursing behaviors that directly affect patient care outcomes, providing a roadmap to improving patient outcomes.

CLINICAL RELEVANCE

Understanding antecedents that affect nurses' attitudes and perceptions of patients with SUD highlights changes that can influence patient outcomes.

PLA-PCL microsphere formulation to deter abuse of prescription opioids by smoking

Opioids are commonly prescribed across the United States (US) for pain relief, despite their highly addictive nature that often leads to abuse and overdose deaths. Abuse deterrent formulations (ADFs) for prescription opioids make the non-therapeutic use of these drugs more difficult and less satisfying. Although approximately one-third of surveyed abusers in the US reported smoking opioids, to our knowledge, no commercialized ADF effectively prevents opioid smoking. Here, we report a novel approach to deter smoking of a model prescription opioid drug, thebaine (THB), by using polymer blend microspheres (MS) comprising polylactic acid (PLA) and polycaprolactone (PCL). We utilized high-performance liquid chromatography (HPLC) and thermogravimetric analysis (TGA) to test the ability of PLA-PCL MS to limit the escape of vaporized THB. Additionally, we compared the abuse-deterrent potential of PLA-PCL MS to that of activated carbon (AC) and mesoporous silica (MPS), two materials with excellent drug-adsorbing properties. Our MS formulation was effective in reducing the amount of both active drug and thermal degradation products in the vapor generated upon heating of THB. These results support that PLA-PCL microspheres can be co-formulated in a tablet with common prescription opioids to deter their abuse via the smoking route.

Prevention, diagnosis, and treatment of opioid use disorder under the supervision of opioid stewardship programs: it's time to act now

The third opium war may have already started, not only due to illicit opioid trafficking from the Golden Crescent and Golden Triangle on the international front but also through indiscriminate opioid prescription and opioid diversion at home. Opioid use disorder (OUD), among unintentional injuries, has become one of the top 4 causes of death in the United States (U.S.). An OUD is defined as a problematic pattern of opioid use resulting in clinically significant impairment or distress, consisting of 2 or more of 11 problems within 1 year, as described by the Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition. Observation of aberrant behaviors of OUD is also helpful for overworked clinicians. For the prevention of OUD, the Opioid Risk Tool and the Current Opioid Misuse Measure are appropriate screening tests before and during opioid administration, respectively. Treatment of OUD consists of 3 opioid-based U.S. Food and Drug Administration-approved medications, including methadone, buprenorphine, and naltrexone, and non-opioid-based symptomatic medications for reducing opioid withdrawal syndromes, such as α2 agonists, β-blockers, antidiarrheals, antiemetics, non-steroidal anti-inflammatory drugs, and benzodiazepines. There are at least 6 recommendable guidelines and essential terms related to OUD. Opioid stewardship programs are now critical to promoting appropriate use of opioid medications, improving patient outcomes, and reducing misuse of opioids, influenced by the successful implementation of antimicrobial stewardship programs. Despite the lack of previous motivation, now is the critical time for trying to reduce the risk of OUD.

Prescription Opioid Misuse in Older Adult Surgical Patients: Epidemiology, Prevention, and Clinical Implications

ABSTRACT

The United States and many other developed nations are in the midst of an opioid crisis, with consequent pressure on prescribers to limit opioid prescribing and reduce prescription opioid misuse. This review addresses prescription opioid misuse for older adult surgical populations. We outline the epidemiology and risk factors for persistent opioid use and misuse in older adults undergoing surgery. We also address screening tools and prescription opioid misuse prevention among vulnerable older adult surgical patients (e.g., older adults with a history of an opioid use disorder), followed by clinical management and patient education recommendations. A significant plurality of older adults engaged in prescription opioid misuse obtain opioid medication for misuse from health providers. Thus, nurses can play a critical role in identifying those older adults at a higher risk for misuse and deliver quality care while balancing the need for adequate pain management against the risk for prescription opioid misuse.

Implementing a pragmatic clinical trial to tailor opioids for acute pain on behalf of the IGNITE ADOPT PGx investigators

Opioid prescribing for postoperative pain management is challenging because of inter-patient variability in opioid response and concern about opioid addiction. Tramadol, hydrocodone, and codeine depend on the cytochrome P450 2D6 (CYP2D6) enzyme for formation of highly potent metabolites. Individuals with reduced or absent CYP2D6 activity (i.e., intermediate metabolizers [IMs] or poor metabolizers [PMs], respectively) have lower concentrations of potent opioid metabolites and potentially inadequate pain control. The primary objective of this prospective, multicenter, randomized pragmatic trial is to determine the effect of postoperative CYP2D6-guided opioid prescribing on pain control and opioid usage. Up to 2020 participants, age ≥8 years, scheduled to undergo a surgical procedure will be enrolled and randomized to immediate pharmacogenetic testing with clinical decision support (CDS) for CYP2D6 phenotype-guided postoperative pain management (intervention arm) or delayed testing without CDS (control arm). CDS is provided through medical record alerts and/or a pharmacist consult note. For IMs and PM in the intervention arm, CDS includes recommendations to avoid hydrocodone, tramadol, and codeine. Patient-reported pain-related outcomes are collected 10 days and 1, 3, and 6 months after surgery. The primary outcome, a composite of pain intensity and opioid usage at 10 days postsurgery, will be compared in the subgroup of IMs and PMs in the intervention (n = 152) versus the control (n = 152) arm. Secondary end points include prescription pain medication misuse scores and opioid persistence at 6 months. This trial will provide data on the clinical utility of CYP2D6 phenotype-guided opioid selection for improving postoperative pain control and reducing opioid-related risks.

Opioid-Related Genetic Polymorphisms of Cytochrome P450 Enzymes after Total Joint Arthroplasty: A Focus on Drug-Drug-Gene Interaction with Commonly Coprescribed Medications

Pharmacogenomic testing, together with the early detection of drug-drug-gene interactions (DDGI) before initiating opioids, can improve the selection of dosage and reduce the risk of adverse drug interactions and therapeutic failures following Total Joint Arthroplasty. The variants of CYP genes can mediate DDGI. Orthopedic surgeons should become familiar with the genetic aspect of opioid use and abuse, as well as the influence of the patient genetic makeup in opioid selection and response, and polymorphic variants in pain modulation.

Diagnosing Prescription Opioid Use Disorder in Patients Using Prescribed Opioids for Chronic Pain

OBJECTIVE

The diagnostic criteria for opioid use disorder, originally developed for heroin, did not anticipate the surge in prescription opioid use and the resulting complexities in diagnosing prescription opioid use disorder (POUD), including differentiation of pain relief (therapeutic intent) from more common drug use motives, such as to get high or to cope with negative affect. The authors examined the validity of the Psychiatric Research Interview for Substance and Mental Disorders, DSM-5 opioid version, an instrument designed to make this differentiation.

METHODS

Patients (N=606) from pain clinics and inpatient substance treatment who ever received a ≥30-day opioid prescription for chronic pain were evaluated for DSM-5 POUD (i.e., withdrawal and tolerance were not considered positive if patients used opioids only as prescribed, per DSM-5 guidelines) and pain-adjusted POUD (behavioral/subjective criteria were not considered positive if pain relief [therapeutic intent] was the sole motive). Bivariate correlated-outcome regression models indicated associations of 10 validators with DSM-5 and pain-adjusted POUD measures, using mean ratios for dimensional measures and odds ratios for binary measures.

RESULTS

The prevalences of DSM-5 and pain-adjusted POUD, respectively, were 44.4% and 30.4% at the ≥2-criteria threshold and 29.5% and 25.3% at the ≥4-criteria threshold. Pain adjustment had little effect on prevalence among substance treatment patients but resulted in substantially lower prevalence among pain treatment patients. All validators had significantly stronger associations with pain-adjusted than with DSM-5 dimensional POUD measures (ratios of mean ratios, 1.22-2.31). For most validators, pain-adjusted binary POUD had larger odds ratios than DSM-5 measures.

CONCLUSIONS

Adapting POUD measures for pain relief (therapeutic intent) improved validity. Studies should investigate the clinical utility of differentiating between therapeutic and nontherapeutic intent in evaluating POUD diagnostic criteria.

Psychological Evaluation of Patients With Cancer Presenting to the Emergency Department With Pain: Independent Predictors of Worse Pain Severity, Interference, and Higher Hourly Opioid Administration

PURPOSE

Pain is a common complaint in patients with cancer presenting to the emergency department (ED). This prospective study evaluated whether biopsychosocial factors could help predict cancer patients with risk of higher pain severity, pain interference, and opioid consumption.

METHODS

Patients with cancer presenting to the ED with a complaint of moderate-severe pain (≥ 4/10-numeric rating scale) completed validated self-report measures assessing sociodemographics, cancer-related treatments, pain severity and interference, medication use, and psychological symptoms (depression, anxiety, pain catastrophizing, and sleep disturbance). Opioids administered and subsequent hospitalization were abstracted. Univariable and multivariable regression analyses assessed factors associated with pain-related outcomes.

RESULTS

Participants (n = 175) presented with a variety of cancer types, with 76% having metastatic disease and 42% reporting current outpatient opioid use. Higher pain catastrophizing, lower depressive symptoms, lower income, outpatient opioid use, and historical chronic pain were independently associated with worse pain (P ≤ .05). Higher pain catastrophizing, anxiety, sleep disturbance, outpatient opioid use, and education were independently associated with worse pain interference (P ≤ .05). The sole independent predictor of ED opioid administration was outpatient opioid use. Patients taking outpatient opioids were younger, had lower health literacy, worse pain catastrophizing, sleep disturbance, depression/anxiety, and greater rates of metastatic cancer and cancer-related surgery (P ≤ .05).

CONCLUSION

Biopsychosocial factors, particularly pain catastrophizing, remained significantly associated with worse pain outcomes for patients with cancer in the ED even after controlling for demographic and clinical variables. Patient outpatient opioid use was independently associated with worse pain, interference, and greater opioid administration, identifying this as a marker for who may benefit most from adjuvant pharmacologic and behavioral interventions.

Machine learning and deep learning frameworks for the automated analysis of pain and opioid withdrawal behaviors

The automation of behavioral tracking and analysis in preclinical research can serve to advance the rate of research outcomes, increase experimental scalability, and challenge the scientific reproducibility crisis. Recent advances in the efficiency, accuracy, and accessibility of deep learning (DL) and machine learning (ML) frameworks are enabling this automation. As the ongoing opioid epidemic continues to worsen alongside increasing rates of chronic pain, there are ever-growing needs to understand opioid use disorders (OUDs) and identify non-opioid therapeutic options for pain. In this review, we examine how these related needs can be advanced by the development and validation of DL and ML resources for automated pain and withdrawal behavioral tracking. We aim to emphasize the utility of these tools for automated behavioral analysis, and we argue that currently developed models should be deployed to address novel questions in the fields of pain and OUD research.

Effects of Intraoperative Opioid Administration on Postoperative Pain and Pain Threshold: A Randomized Controlled Study

Fentanyl and short-acting remifentanil are often used in combination. We evaluated the effect of intraoperative opioid administration on postoperative pain and pain thresholds when the two drugs were used. Patients who underwent gynecological laparoscopic surgery were randomly assigned into two groups (15 patients each) to receive either sufficient (group A) or minimum (group B) fentanyl (maximum estimated effect site concentration: A: 7.86 ng/mL, B: 1.5 ng/mL). The estimated effect site concentration at the end of surgery was adjusted to the same level (1 ng/mL). Patients in both groups also received continuous intravenous remifentanil during surgery. The primary outcome was the pressure pain threshold, as evaluated by a pressure algometer 3 h postoperatively. The pressure pain threshold at 3 h postoperatively was 51.1% (95% CI: [44.4–57.8]) in group A and 56.6% [49.5–63.6] in group B, assuming a preoperative value of 100% (p = 0.298). There were no significant differences in pressure pain threshold and numeric rating scale scores between the groups after surgery. The pain threshold decreased significantly in both groups at 3 h postoperatively compared to preoperative values, and recovered at 24 h. Co-administration of both opioids caused hyperalgesia regardless of fentanyl dose.

Evaluation by Survival Analysis of Cold Pain Tolerance in Patients with Fibromyalgia and Opioid Use

Purpose

The cold pressor test (CPT) is a clinical pain research method used to measure cold pain tolerance. During this test, participants immerse an extremity (ie, hand or foot) into cold water for as long as tolerable. The duration of the test (traditionally up to an experimentally imposed cut-off at 2 minutes) indicates the amount of cold pain tolerance by the participant. Prior research studies have investigated cold pain tolerance in patients with chronic pain. However, few of these studies have used survival analysis, which allows for proper handling of data censoring and is therefore, an optimal statistical method for CPT data analysis. The goal of the present study was to use survival analysis to evaluate cold pain tolerance in patients with fibromyalgia. Furthermore, we aimed to model relationships between psychological and clinical variables as well as opioid medication use and cold pain tolerance.

Patients and Methods

A total of 85 patients with fibromyalgia (42 who were taking opioids) and 47 healthy pain-free controls provided CPT and questionnaire data (collected across 2 study sites) for a case-control study. We used survival analysis using Cox regression to evaluate group differences (patients vs controls) in cold pain tolerance and to evaluate cold pain tolerance relationships with psychological, clinical, and medication use.

Results

As compared to healthy controls, patients with fibromyalgia exhibited significantly lower CPT survival (HR = 2.17, 95% CI: [1.42, 3.31], p = 0.00035). As indicated by Cox regression models, the significant group difference in CPT survival did not relate to our selected psychological and clinical measures (p > 0.05). The groups of non-opioid-taking patients and healthy controls showed consistent CPT survival across study sites. However, patients taking opioid pain medications showed differences in CPT survival across study sites.

Conclusion

By using survival analysis, an optimal method for time-to-event pain measures such as the CPT, we confirmed previously identified reductions in cold pain tolerance in patients with fibromyalgia. While our selected psychological and clinical measures were not significantly associated with cold pain tolerance, our data suggest that opioid medication use may impart greater cold pain tolerance in some patients.

Differential patterns of opioid misuse between younger and older adults - a retrospective observational study using data from South Carolina's prescription drug monitoring program

Background: Most research on opioid misuse focuses on younger adults, yet opioid-related mortality has risen fastest among older Americans over age 55.Objectives: To assess whether there are differential patterns of opioid misuse over time between younger and older adults and whether South Carolina's mandatory Prescription Drug Monitoring Program (PDMP) affected opioid misuse differentially between the two groups.Methods: We used South Carolina's Reporting and Identification Prescription Tracking System from 2010 to 2018 to calculate an opioid misuse score for 193,073 patients (sex unknown) using days' supply, morphine milligram equivalents (MME), and the numbers of unique prescribers and dispensaries. Multivariable regression was used to assess differential opioid misuse patterns by age group over time and in response to implementation of South Carolina's mandatory PDMP in 2017.Results: We found that between 2011 and 2018, older adults received 57% (p < .01) more in total MME and 25.4 days more (p < .01) in supply, but received prescriptions from fewer doctors (-0.063 doctors, p < 01) and pharmacies (-0.11 pharmacies, p < 01) per year versus younger adults. However, older adults had lower odds of receiving a high misuse score (OR 0.88, p < .01). After the 2017 legislation, misuse scores fell among younger adults (OR 0.79, p < .01) relative to 2011, but not among older adults.Conclusion: Older adults may misuse opioids differently compared to younger adults. Assessment of policies to reduce opioid misuse should take into account subgroup differences that may be masked at the population level.

Mechanism of opioid addiction and its intervention therapy: Focusing on the reward circuitry and mu-opioid receptor

Opioid abuse and addiction have become a global pandemic, posing tremendous health and social burdens. The rewarding effects and the occurrence of withdrawal symptoms are the two mainstays of opioid addiction. Mu-opioid receptors (MORs), a member of opioid receptors, play important roles in opioid addiction, mediating both the rewarding effects of opioids and opioid withdrawal syndrome (OWS). The underlying mechanism of MOR-mediated opioid rewarding effects and withdrawal syndrome is of vital importance to understand the nature of opioid addiction and also provides theoretical basis for targeting MORs to treat drug addiction. In this review, we first briefly introduce the basic concepts of MORs, including their structure, distribution in the nervous system, endogenous ligands, and functional characteristics. We focused on the brain circuitry and molecular mechanism of MORs-mediated opioid reward and withdrawal. The neuroanatomical and functional elements of the neural circuitry of the reward system underlying opioid addiction were thoroughly discussed, and the roles of MOR within the reward circuitry were also elaborated. Furthermore, we interrogated the roles of MORs in OWS, along with the structural basis and molecular adaptions of MORs-mediated withdrawal syndrome. Finally, current treatment strategies for opioid addiction targeting MORs were also presented.

Profiles of adult people in a Spanish sample with chronic pain: Cluster analysis

AIM

To establish groups of people with chronic non-cancer pain according to the impairment caused by pain and to identify factors associated with the group with a higher level of impairment.

BACKGROUND

Knowing the profiles of people who suffer from chronic non-cancer pain could make it possible to direct their treatment and to detect associated risks.

DESIGN

A cross-sectional study.

METHODS

A sample of 395 people with chronic non-cancer pain was collected in Pain Units and Primary Healthcare Centres in southern Spain (January to March 2020). A cluster analysis was performed to divide the population into groups and a binary logistic regression model was established to determine factors associated with the group with a higher level of impairment.

RESULTS

Two groups were identified: lower level of impairment due to pain, characterized by being 45-65 years old, not medicated with opioids or anxiolytics, employed and with a mild level of impact on daily life; and higher level of impairment characterized by being older than 65 years old, medicated with opioids and anxiolytics, retired or on medical leave and with a severe impact on daily life. In addition, among women, being widowed, single or a smoker are risk factors for belonging to the group with a higher level of impairment; being smokers or consuming alcohol three or less times a week would be risk factors in men.

CONCLUSIONS

Age, chronic non-cancer pain impact on daily life, work situation and the consumption of opioid drugs and/or anxiolytics are factors that appear to influence the level of impairment due to chronic pain.

IMPACT

These findings could help detect impairment due to pain in its early stages, determining the specific needs of each person.

Trends in opioid overdose fatalities in Cuyahoga County, Ohio: Multi-drug mixtures, the African-American community and carfentanil

Background

Ohio's age-adjusted opioid overdose fatality rate is double the national average. In an ever-evolving epidemic, it is crucial to monitor trends to inform public health interventions.

Methods

A retrospective study was conducted using the Medical Examiner's decedent case files for all accidental opioid-related adult overdose deaths in Cuyahoga County (Cleveland), Ohio in 2017. Characterization of trends was based on autopsy/toxicology and first responder reports, medical records and death scene investigations.

Results

Of 543 accidental opioid-related adult overdose fatalities, 64.1% died from 3+ drugs. The most common cause of death (COD) drugs included fentanyl (63.4%), heroin (44.4%), cocaine (37.0%) and carfentanil (35.0%). There were four times as many African American decedents as two years prior. Three or more COD drugs was >50% more common in those with fentanyl (Prevalence Ratio (PR) = 1.56[1.34-1.70]; p<.001) or carfentanil (PR = 1.51[1.33-1.70]; p<.001) as a COD drug, more common with a history of prescription drug abuse (PR = 1.16[1.02-1.33]; p=.025), but less common in divorced/widowed decedents (PR = 0.83[0.71-0.97]; p=.022). Carfentanil was nearly 4 times as prevalent in those with previous illicit drug use (PR = 3.88[1.09-13.70]; p=.025), and less common in those with previous medical history (PR = 0.72[0.55-0.94]; p=.016) or age 50+ (PR = 0.72[0.53-0.97]; p=.031).

Conclusions

Accidental opioid-related overdose fatalities in Cuyahoga County adults were dominated by 3+ COD drugs, with cocaine/fentanyl mixtures driving sharp increases in African American fatalities. Carfentanil was more prevalent in people fitting the profile of recreational drug use. This data can inform harm reduction interventions.

The role of kappa opioid receptors in immune system - An overview

Opioids are one of the most effective anti-nociceptive agents used in patients with cancer pain or after serious surgery in most countries. The endogenous opioid system participates in pain perception, but recently its role in inflammation was determined. κ-opioid receptors (KOP receptors), a member of the opioid receptor family, are expressed in the central and peripheral nervous system as well as on the surface of different types of immune cells, e.g. T cells, B cells and monocytes. In this review, we focused on the involvement of KOP receptors in the inflammatory process and described their function in a number of conditions in which the immune system plays a key role (e.g. inflammatory bowel disease, arthritis, subarachnoid hemorrhage, vascular dysfunction) and inflammatory pain. We summed up the application of known KOP ligands in pathophysiology and we aimed to shed new light on KOP receptors as important elements during inflammation.

Psychedelic drug abuse potential assessment research for new drug applications and Controlled Substances Act scheduling

New medicines containing classic hallucinogenic and entactogenic psychedelic substance are under development for various psychiatric and neurological disorders. Many of these, including psilocybin, lysergic acid diethylamide (LSD), and 3,4-methylenedioxymethamphetamine (MDMA) are Schedule I controlled substances of the United States Controlled Substances Act (US CSA), and similarly controlled globally. The implications of the CSA for research and medicines development, the path to approval of medicines, and their subsequent removal from Schedule I in the US are discussed. This entire process occurs within the framework of the CSA in the US and its counterparts internationally in accordance with international drug control treaties. Abuse potential related research in the US informs the eight factors of the CSA which provide the basis for rescheduling actions that must occur upon approval of a drug that contains a Schedule I substance. Abuse-related research also informs drug product labeling and the risk evaluation and mitigation strategies (REMS) will likely be required for approved medicines. Human abuse potential studies typically employed in CNS drug development may be problematic for substances with strong hallucinogenic effects such as psilocybin, and alternative strategies are discussed. Implications for research, medicinal development, and controlled substance scheduling are presented in the context of the US CSA and FDA requirements with implications for global regulation. We also discuss how abuse-related research can contribute to understanding mechanisms of action and therapeutic effects as well as the totality of the effects of the drugs on the brain, behavior, mood, and the constructs of spirituality and consciousness.

The Role of Neuro-Immune Interactions in Chronic Pain: Implications for Clinical Practice

Chronic pain remains a public health problem and contributes to the ongoing opioid epidemic. Current pain management therapies still leave many patients with poorly controlled pain, thus new or improved treatments are desperately needed. One major challenge in pain research is the translation of preclinical findings into effective clinical practice. The local neuroimmune interface plays an important role in the initiation and maintenance of chronic pain and is therefore a promising target for novel therapeutic development. Neurons interface with immune and immunocompetent cells in many distinct microenvironments along the nociceptive circuitry. The local neuroimmune interface can modulate the activity and property of the neurons to affect peripheral and central sensitization. In this review, we highlight a specific subset of many neuroimmune interfaces. In the central nervous system, we examine the interface between neurons and microglia, astrocytes, and T lymphocytes. In the periphery, we profile the interface between neurons in the dorsal root ganglion with T lymphocytes, satellite glial cells, and macrophages. To bridge the gap between preclinical research and clinical practice, we review the preclinical studies of each neuroimmune interface, discuss current clinical treatments in pain medicine that may exert its action at the neuroimmune interface, and highlight opportunities for future clinical research efforts.

Characteristics of non-fatal overdoses and associated risk factors in patients attending a specialist community-based substance misuse service

Introduction

There are concerns about rising drug-related deaths and the potential contribution of prescription analgesics. There is limited understanding regarding the role of prescription analgesics in non-fatal overdoses (NFODs), nor is there a good understanding of what factors are associated with more severe overdose.

Objectives

To explore risk factors and characteristics of NFODs among people attending a specialist community-based substance misuse service.

Methods

After Caldicott approval, data on NFODs, in people attending the Tayside Substance Misuse Service (TSMS), were extracted from the Scottish Ambulance Service database, along with opioid replacement therapy (ORT) prescribing data. Statistical analysis was performed using R studio and Microsoft Excel.

Results

557 people (78% [434/556] male, mean age ± standard deviation 38.4 ± 7.95) had an NFOD. Repeat NFODs were more likely in males compared to females (p < .0065). Males were more likely to be administered naloxone (OR = 1.94, 95% CI = 1.10-3.40, p < .02). NFODs at home were more likely to be moderate to severe (categorized by Glasgow Comma Scale [p < .02, OR = 4.95, 95% CI = 1.24-24.38]). Methadone (321/557, 57.63%), benzodiazepines (281/557, 50.45%) and heroin (244/557, 43.81%) were the commonest substances: prescribed methadone overdose was more likely than buprenorphine (p < .00001). Opioids and benzodiazepines were often taken together (275/557, 49.40%), with almost all gabapentinoid NFODs also involving opioids (60/61, 98.40%).

Conclusions

Polysubstance use with opioids prescribed for ORT, such as methadone, is highly likely to be implicated in NFOD, with males being at the highest risk of severe and repeat NFOD. Future work should focus on strategies to further reduce NFODs.