Chronic pain prevalence and analgesic prescribing in a general medical population

Cannabinoid-Induced Inhibition of Morphine Glucuronidation and the Potential for In Vivo Drug-Drug Interactions

Opioids are commonly prescribed for the treatment of chronic pain. Approximately 50% of adults who are prescribed opioids for pain co-use cannabis with their opioid treatment. Morphine is primarily metabolized by UDP-glucuronosyltransferase (UGT) 2B7 to an inactive metabolite, morphine-3-glucuronide (M3G), and an active metabolite, morphine-6-glucuronide (M6G). Previous studies have shown that major cannabis constituents including Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) inhibit major UGT enzymes. To examine whether cannabinoids or their major metabolites inhibit morphine glucuronidation by UGT2B7, in vitro assays and mechanistic static modeling were performed with these cannabinoids and their major metabolites including 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC), 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (11-COOH-THC), 7-hydroxy-cannabidiol (7-OH-CBD), and 7-carboxy-cannabidiol (7-COOH-CBD). In vitro assays with rUGT-overexpressing microsomes and human liver microsomes showed that THC and CBD and their metabolites inhibited UGT2B7-mediated morphine metabolism, with CBD and THC exhibiting the most potent Ki,u values (0.16 µM and 0.37 µM, respectively). Only 7-COOH-CBD exhibited no inhibitory activity against UGT2B7-mediated morphine metabolism. Static mechanistic modeling predicted an in vivo drug-drug interaction between morphine and THC after inhaled cannabis, and between THC, CBD, and 7-OH-CBD after oral consumption of cannabis. These data suggest that the co-use of these agents may lead to adverse drug events in humans.

Pain and Its Management in Patients Referred to a Geriatric Outpatient Clinic

(1) Background: A major problem affecting geriatric patients is pain. In addition to pain, a significant problem of old age is dementia and depression, which can hinder the diagnosis and treatment of pain. The aim of this study was to analyse the prevalence of pain in patients treated in a geriatric outpatient clinic and the treatment used. (2) Methods: The analysis was based on the records of 937 patients who visited the Geriatric Outpatient Clinic in Dobre Miasto between 2015 and 2020. Based on records containing data dating back to their first visit to the hospital, patients' experiences of pain, the presence of depressive symptoms and dementia, and the pharmacological treatment used for pain (analgesics and coanalgesics) were analysed. (3) Results: Pain complaints were reported by 311 patients (33.2% of the study group), 76% of the complaints were from females. The mean age of the patients was 78 years (SD = 8.45). At least one analgesic drug was taken by 107 patients (34.4%). The most commonly used analgesics were opioids (63 patients, 58.87%), especially tramadol. Of the potential coanalgesics, the largest number of patients used an antidepressant. (4) Conclusions: Despite the widespread prevalence of pain among the elderly, only about one-third of them were taking pain medication, mainly in the form of weak opioids. Patients with symptoms of dementia were found to report pain less frequently.

Rationale and design of a multisite randomized clinical trial examining an integrated behavioral treatment for veterans with co-occurring chronic pain and opioid use disorder: The pain and opioids integrated treatment in veterans (POSITIVE) trial

BACKGROUND

Chronic pain and opioid use disorder (OUD) individually represent a risk to health and well-being. Concerningly, there is evidence that they are frequently co-morbid. While few treatments exist that simultaneously target both conditions, preliminary work has supported the feasibility of an integrated behavioral treatment targeting pain interference and opioid misuse. This treatment combined Acceptance and Commitment Therapy (ACT) and Mindfulness-Based Relapse Prevention (ACT+MBRP). This paper describes the protocol for the adequately powered efficacy study of this integrated treatment.

METHODS

A multisite randomized controlled trial will examine the efficacy of ACT+MBRP in comparison to a parallel education control condition, focusing on opioid safety and pain education. Participants include veterans (n = 160; 21-75 years old) recruited from three Veterans Administration (VA) Healthcare Systems with chronic pain who are on a stable dose of buprenorphine. Both conditions include twelve weekly 90 min group sessions delivered via telehealth. Primary outcomes include pain interference (Patient Reported Outcome Measurement Information System - Pain Interference) and hazardous opioid use (Current Opioid Misuse Measure), which will be examined at the end of the active treatment phase and through 12 months post-intervention. Secondary analyses will evaluate outcomes including pain intensity, depression, pain-related fear, and substance use, as well as treatment mechanisms.

CONCLUSION

This study will determine the efficacy of an integrated behavioral treatment program for pain interference and hazardous opioid use among veterans with chronic pain and OUD who are prescribed buprenorphine, addressing a critical need for more integrated treatments for chronic pain and OUD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04648228.

Opioid prescribing practices in chronic kidney disease: a population-based cohort study

BACKGROUND

Chronic pain is common, and its management is complex in patients with chronic kidney disease (CKD), but limited data are available on opioid prescribing. We examined opioid prescribing for non-cancer and non-end-of-life care in patients with CKD.

METHODS

This was a population-based retrospective cohort study using administrative databases in Ontario, Canada which included adults with CKD defined by an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 from 1 November 2012 to 31 December 2018 and estimated the proportion of opioid prescriptions (type, duration, dose, potentially inappropriate prescribing, etc.) within 1 year of cohort entry. Prescriptions had to precede dialysis, kidney transplant or death.

RESULTS

We included 680 445 adults with CKD, and 198 063 (29.1%) were prescribed opioids. Codeine (14.9%) and hydromorphone (7.2%) were the most common opioids. Among opioid users, 24.3% had repeated or long-term use, 26.1% were prescribed high doses and 56.8% were new users. Opioid users were more likely to be female, had cardiac disease or a mental health diagnosis, and had more healthcare visits. The proportions for potentially inappropriate prescribing indicators varied (e.g. 50.1% with eGFR <30 were prescribed codeine, and 20.6% of opioid users were concurrently prescribed benzodiazepines, while 7.2% with eGFR <30 mL/min/1.73 m2 were prescribed morphine, and 7.0% were received more than one opioid concurrently). Opioid prescriptions declined with time (2013 cohort: 31.1% versus 2018 cohort: 24.5%; p <0.0001), as did indicators of potentially inappropriate prescribing.

CONCLUSIONS

Opioid use was common in patients with CKD. While opioid prescriptions and potentially inappropriate prescribing have declined in recent years, interventions to improve pain management without the use of opioids and education on safer prescribing practices are needed.

Impact of Informed Consent and Education on Care Engagement After Opioid Initiation in the Veterans Health Administration

Objective

To ensure all patients receiving long-term opioid therapy (LTOT) understand the risks, benefits and treatment alternatives, the Veterans Health Administration (VHA) released a national policy in 2014 to standardize a signature informed consent (SIC) process. We evaluated the impact of this policy on medical follow-up after LTOT initiation, a guideline recommended practice.

Methods

Using VHA administrative data, we identified patients initiating LTOT between May 2013 and May 2016. We used an interrupted time series design to compare the monthly rates of medical follow-up within 30 days and primary care visits within 3 months after LTOT initiation across three periods: 12 months before the policy (Year 1); 12 months after policy release (Year 2); and 12-24 months after policy release, when the SIC process was mandatory (Year 3).

Results

Among the 409,895 patients who experienced 758,416 LTOT initiations, medical follow-up within 30 days and primary care engagement within 3 months increased by 4% between Year 1 and Year 3. Compared to Year 1, patients in Year 3 were 1.12 times more likely to have any medical follow-up (95% CI: 1.10, 1.13) and 1.13 times more likely to have a primary care visit (95% CI: 1.12, 1.15). Facilities with a greater proportion of patients receiving SIC had increased medical follow-up (RR: 1.04, 95% CI: 1.01, 1.07) and primary care engagement (RR: 1.06, 95% CI: 1.03, 1.10).

Conclusion

The VHA's SIC policy is associated with increased medical follow-up among patients initiating LTOT, which may result in improved patient safety and has implications for other healthcare settings.

P2Y1 purinergic receptor inhibition attenuated remifentanil-induced postoperative hyperalgesia via decreasing NMDA receptor phosphorylation in dorsal root ganglion

BACKGROUND

Remifentanil-induced postoperative hyperalgesia is an intractable side effect of the clinical use of remifentanil, the mechanism of which remains obscure, especially in the peripheral nervous system. N-methyl-D-aspartate receptor (NMDAR) phosphorylation in dorsal root ganglion (DRG) plays a pronociceptive role in neuropathic pain. The contribution of the P2Y1 purinergic receptor (P2Y1R) in DRG to pain hypersensitivity derived from various origins and P2Y1R upregulation-induced NMDAR activation in neurons have also been uncovered. This study aimed to investigate whether P2Y1R participates in nociceptive processing in the DRG and spinal cord in remifentanil-induced postoperative hyperalgesia.

METHODS

Rats with remifentanil-induced postoperative hyperalgesia were intrathecally injected with NMDAR antagonist MK801 or P2Y1R antagonist MRS2179 at 10 min prior to remifentanil infusion. Mechanical allodynia, heat hyperalgesia, and cold hyperalgesia were measured at -24 h, 2 h, 6 h, 24 h, and 48 h following remifentanil infusion. The P2Y1R expression and NMDAR expression and phosphorylation in DRG ipsilateral to the incision were detected by Western blot and immunofluorescence.

RESULTS

Incision and remifentanil induced mechanical allodynia, heat hyperalgesia, and cold hyperalgesia accompanied by upregulated P2Y1R expression, increased NMDAR subunit NR1 expression and phosphorylation at Ser896, and NR2B expression and phosphorylation at Tyr1472 in DRG. Inhibition of NMDAR phosphorylation by MK801 effectively attenuated remifentanil-induced postoperative hyperalgesia. Furthermore, P2Y1R blockade by MRS2179 not only lessened remifentanil-evoked postoperative hypersensitivity to mechanical, heat, and cold stimuli, but also suppressed the increases in NR1 and NR2B expression and phosphorylation in DRG induced by incision and remifentanil.

CONCLUSION

The process by which P2Y1R mediates NMDAR expression and phosphorylation represents a mechanism of remifentanil-induced postoperative hyperalgesia in the DRG and/or spinal cord.

Association of 3 CDC opioid prescription guidelines for chronic pain and 2 payer pharmacy coverage changes on opioid initiation practices

BACKGROUND: Due to the US opioid epidemic, in March of 2016, the Centers for Disease Control and Prevention (CDC) published new guidelines for primary care providers on opioid prescribing for chronic pain. Payer coverage changes were also implemented to help modify opioid prescribing behavior. Whether these initiatives were associated with changes in opioid initiation patterns is unknown. OBJECTIVE: To assess the association between 3 of the 2016 CDC guidelines and 2 subsequent payer pharmacy coverage changes with changes in opioid initiation behavior across different provider specialties. METHODS: We conducted a real-world evidence study using claims data from OptumLabs Data Warehouse between January of 2014 and December of 2018. Subjects were continuously enrolled opioid naive patients, aged at least 18 years, who had at least 1 chronic pain diagnosis within 2 weeks before their first (first-time) opioid prescription. The study used multiple treatment period segmented regression analysis to evaluate the association, across different provider specialties, between the CDC guideline release and the payer pharmacy coverage changes with immediate change in level and overall change in the rate of first-time extended-release opioid prescriptions, firsttime opioid prescriptions at doses of at least 50 MME (morphine milligram equivalent) per day, and first-time opioid prescriptions with overlapping benzodiazepine prescription. RESULTS: The CDC guidelines were not associated with any change in the rate of first-time prescriptions of extended-release opioids. However, a January 2017 payer pharmacy coverage change was associated with a reduction over time in first-time extended-release opioid prescription rates by 22.15 in every 100,000 prescriptions (CI = -40.04 to -2.92, P = 0.013). The CDC guidelines were associated with an immediate decline in level of first-time opioid prescription at doses of at least 50 MME per day by 74.00 in every 10,000 prescriptions (CI = -124.86 to -23.13, P = 0.004) and an increased rate of decline over time by 13.64 in every 10,000 prescriptions (CI = -17.07 to -10.21, P < 0.001). These associations varied across provider types and specialties. The March 2018, payer coverage change was associated with an immediate reduction in level of first-time opioid prescriptions at doses of at least 50 MME per day across all specialties and an increased reduction over time among surgeons. The CDC guidelines were associated, respectively, with a reduction in the rate of overlapping first-time opioid prescriptions with benzodiazepines among family medicine, internal medicine, surgeons, emergency medicine providers, and providers with unknown specialty by 6.11, 5.10, 2.89, 11.43, and 9.11 in every 10,000 prescriptions monthly (CI = -9.48 to -2.73, -9.86 to -0.35, -5.40 to -0.38, -17.26 to -5.61 and -11.96 to -6.25, respectively, P < 0.001, P = 0.035, P = 0.024, P < 0.001 and P < 0.001). CONCLUSIONS: Some specialist providers also adopted the CDC guidelines, and the response to the guidelines differed across various provider specialties. Some CDC guidelines were associated with a reduction in high-risk first-time opioid prescriptions. Payer pharmacy coverage changes reinforced the guidelines both in situations where the CDC guidelines did and did not show any association. DISCLOSURE: This research was funded by Agency for Healthcare Research and Quality (R01 HS025164; PI: Karaca-Mandic). Karaca-Mandic reports grants from the American Cancer Society and Sempre Health, along with fees from Tactile Medical and Precision Health Economics, unrelated to this study. The other authors have nothing to disclose.

Treatment Preferences for Chronic Low Back Pain: Views of Veterans and Their Providers

Purpose

This study was conducted to characterize chronic low back pain (cLBP) and to identify treatment histories and preferences for cLBP management among Veterans and primary care providers within the Veterans Affairs (VA) healthcare system.

Participants and Methods

Veterans with cLBP from five geographically diverse VA medical centers were identified using International Classification of Diseases (ICD) 9 and 10 codes from VA administrative data as were primary care providers at these same sites. From these data, Veterans (200/per site) and providers (160/per site) were selected and mailed surveys. Open-ended interview data were collected from a subset of Veterans and providers.

Results

In total, 235 Veterans and 67 providers returned completed surveys. More than 80% of the Veteran respondents had daily back pain for more than 1 year. Most Veterans had tried several treatments for their pain with medications and physical therapy being the most commonly used. Veterans and providers had similar attitudes towards many cLBP treatments with the exception of psychological therapies that were more favored by providers. Open-ended interview data showed that Veterans and providers emphasized the need for multi-component approaches to treatment.

Conclusion

Among Veterans, cLBP is typically of sustained duration, is relatively severe, and also interferes significantly with normal functioning. Veterans are experienced with respect to treatments and had similar attitudes towards many cLBP treatments as their providers, especially tailored approaches.

Pain Alleviation and Opioid Weaning in an 80-Year-Old with Chronic Foot Pain Following Injection Therapy with Perineural Dexmedetomidine and Dexamethasone

Opiates are routinely used for chronic pain patients, and up to 44% of them will have a prescription for an opiate medication for pain alleviation. However, of the 76 million adults prescribed opiates for pain management, about 12% report misuse, and a large number of these may find themselves addicted to opioid medications. Opioid addiction is an ongoing epidemic, costing many lives. Withdrawal is very difficult. This requires providers to consider alternative analgesic plans and minimize opiate use. Here we report the use of a dexamethasone-dexmedetomidine combination for a regional nerve block in an elderly woman chronically treated with opiate medications who had previously failed opiate weaning. Following her nerve block, she was able to completely wean off of opioids and continues having good pain control with an opioid-free regimen.

Progress in opioid reward research: From a canonical two-neuron hypothesis to two neural circuits

Opioid abuse and related overdose deaths continue to rise in the United States, contributing to the national opioid crisis in the USA. The neural mechanisms underlying opioid abuse and addiction are still not fully understood. This review discusses recent progress in basic research dissecting receptor mechanisms and circuitries underlying opioid reward and addiction. We first review the canonical GABA-dopamine neuron hypothesis that was upheld for half a century, followed by major findings challenging this hypothesis. We then focus on recent progress in research evaluating the role of the mesolimbic and nigrostriatal dopamine circuitries in opioid reward and relapse. Based on recent findings that activation of dopamine neurons in the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) is equally rewarding and that GABA neurons in the rostromedial tegmental nucleus (RMTg) and the substantia nigra pars reticula (SNr) are rich in mu opioid receptors and directly synapse onto midbrain DA neurons, we proposed that the RTMg→VTA → ventrostriatal and SNr → SNc → dorsostriatal pathways may act as the two major neural substrates underlying opioid reward and abuse. Lastly, we discuss possible integrations of these two pathways during initial opioid use, development of opioid abuse and maintenance of compulsive opioid seeking.

Postoperative Pain Management of Non-"Opioid-Naive" Patients Undergoing Hand and Upper-Extremity Surgery

Background: Patients with prior opioid use are often difficult to manage postoperatively. We examined potential strategies for managing these patients: (1) prescribing a different opioid; and (2) encouraging the use of nonopioid analgesics over opioids. Methods: A pain control program was implemented at an outpatient hand and upper-extremity center. Patients were recruited before (n = 305) and after (n = 225) implementation. Seventy of them were taking opioids prior to surgery. Information about pain control satisfaction and opioid use was collected. The Fisher exact test was used to compare categorical variables with small expected frequencies. Wilcoxon rank sum test was used to compare nonnormally distributed continuous variables. Results: Opioid users used 28.8 ± 25.6 opioid pills; nonopioid users used 14.5 ± 21.5 pills. Furthermore, 41.4% of opioid users sought more pills after surgery compared with 14.0% among nonopioid users. The pain control program was more effective in reducing opioid consumption and waste and increasing nonopioid consumption for nonopioid users than for opioid users. Prior opioid users who were prescribed a different opioid after surgery used 24.6 ± 22.0 opioid pills. Patients prescribed the same opioid used 37.9 ± 30.8 pills. Conclusions: Patients taking opioids prior to hand and upper-extremity surgery use more opioid pills, seek more pills after surgery, and are less satisfied with their pain control than their nonopioid user counterparts. Furthermore, the comprehensive pain plan was less effective in this patient population. Prescribing a different opioid reduced medication requirements for these patients, but additional strategies are needed to address postoperative pain management.

Total Knee Arthroplasty: Opioid-Free Analgesia in a Patient with Opioid-Induced Hyperalgesia: A Case Report

CASE

Pain control after total knee arthroplasty (TKA) remains a significant challenge, especially in the context of certain patient-specific factors. We present a case of a 59-year-old woman with opioid-induced hyperalgesia who was referred for left knee pain and end-stage tricompartmental degenerative joint disease after failure of conservative management. We outline an approach to control postoperative pain in patients undergoing TKA who have severe opioid contraindications.

CONCLUSIONS

TKA and rehabilitation with a 6-year follow-up period was accomplished using a multimodal nonopioid approach, consisting of a combination of gabapentin, acetaminophen, ketorolac, meloxicam, methocarbamol, a tunneled femoral nerve catheter, and periarticular injection.

What proportion of patients with chronic noncancer pain are prescribed an opioid medicine? Systematic review and meta-regression of observational studies

Guidelines now discourage opioid analgesics for chronic noncancer pain because the benefits frequently do not outweigh the harms. We aimed to determine the proportion of patients with chronic noncancer pain who are prescribed an opioid, the types prescribed and factors associated with prescribing. Database searches were conducted from inception to 29 October 2018 without language restrictions. We included observational studies of adults with chronic noncancer pain measuring opioid prescribing. Opioids were categorized as weak (e.g. codeine) or strong (e.g. oxycodone). Study quality was assessed using a risk of bias tool designed for observational studies measuring prevalence. Individual study results were pooled using a random-effects model. Meta-regression investigated study-level factors associated with prescribing (e.g. sampling year, geographic region as per World Health Organization). The overall evidence quality was assessed using Grading of Recommendations Assessment, Development and Evaluation criteria. Of the 42 studies (5,059,098 participants) identified, the majority (n = 28) were from the United States of America. Eleven studies were at low risk of bias. The pooled estimate of the proportion of patients with chronic noncancer pain prescribed opioids was 30.7% (95% CI 28.7% to 32.7%, n = 42 studies, moderate-quality evidence). Strong opioids were more frequently prescribed than weak (18.4% (95% CI 16.0-21.0%, n = 15 studies, low-quality evidence), versus 8.5% (95% CI 7.2-9.9%, n = 15 studies, low-quality evidence)). Meta-regression determined that opioid prescribing was associated with year of sampling (more prescribing in recent years) (P = 0.014) and not geographic region (P = 0.056). Opioid prescribing for patients with chronic noncancer pain is common and has increased over time.

Between- and within-person associations between opioid overdose risk and depression, suicidal ideation, pain severity, and pain interference

BACKGROUND

To better understand overdose (OD) risk and develop tailored overdose risk interventions, we surveyed 234 opioid-using veterans residing in New York City, 2014-2017. Our aim was to better understand how predictors of OD may be associated with physical and mental health challenges, including pain severity and interference, depression and suicidal ideation over time.

METHODS

Veterans completed monthly assessments of the Overdose Risk Behavior Scale (ORBS), pain severity and interference, suicidal ideation, and depression for up to two years and were assessed an average of 14 times over 611 days. To estimate between-person and within-person associations between time-varying covariates and opioid risk behavior, mixed-effects regression was used on the 145-person subsample of veterans completing the baseline and at least three follow-up assessments.

RESULTS

The level of each time-varying covariate at the average of study time (between-person effect) was positively related to ORBS for pain severity and interference, suicidal ideation, and depression. Deviations from individuals' personal trajectories (within-person effect) were positively related to ORBS for pain severity and interference, suicidal ideation, and depression.

CONCLUSIONS

US military veterans endure physical and mental health challenges elevating risk for opioid-related overdose. When pain severity, pain interference, suicidal ideation and depression were higher than usual, opioid risk behavior was higher. Conversely, when these health issues were less of a problem than usual, opioid risk behavior was lower. Assessing the physical and mental health of opioid-using veterans over time may support the development and implementation of interventions to reduce behaviors that increase the likelihood of overdose.

Military veterans' overdose risk behavior: Demographic and biopsychosocial influences

BACKGROUND

U.S. military veterans face many biopsychosocial (BPS) challenges post-service that may elevate risk for opioid-related overdose including physical pain, mental health concerns and social stressors. Some veterans use opioids to manage pain and cope with social readjustment. This study assessed associations between BPS factors and recent engagement in overdose risk behavior in a community sample of post-9/11 veterans who used opioids in New York City.

METHODS

Participants (n = 218) were recruited through convenience sampling and completed a baseline assessment including a validated Opioid Risk Behavior Scale (ORBS) that measured past-30-day engagement in 22 opioid-related overdose risk behaviors. Analyses examined associations between ORBS scores and hypothesized demographic, biological/physical, psychological and social predictors. Incident rate ratios estimated the expected relative difference in ORBS score associated with each predictor.

RESULTS

Participants reported an average of 4.72 overdose risk behaviors in the past 30 days. Significant independent predictors of higher ORBS score, after adjustment for demographics and current prescription medications, were past-30-day: depression symptoms; unsheltered or living in a homeless shelter (vs. private housing); history of mental health treatment; experiencing stressful life events; average pain severity; and pain interference.

CONCLUSION

Veterans face myriad BPS challenges and, while drug-related overdose risks are well understood, findings suggest that other factors-including mental health, pain and stressful life events-may also be associated with overdose risk among opioid-using veterans. The larger challenges veterans face should be considered in the context of BPS forms of pain management when tailoring and delivering overdose prevention interventions.

Integrated Behavioral Treatment for Veterans With Co-Morbid Chronic Pain and Hazardous Opioid Use: A Randomized Controlled Pilot Trial

Opioid prescription in the treatment of chronic pain is frequent and carries a risk of increased morbidity and mortality in a clinically significant number of patients, particularly those who are using opioids in a hazardous manner. Few treatment options are available that target both pain-related interference and hazardous opioid use among patients with chronic pain. In military Veterans, this issue is of particular importance as numerous reports indicate continued high rates of opioid prescription for chronic pain, as well as significant opioid-related problems. The overall aim of the present study was to determine the feasibility of an integrated psychosocial treatment in Veterans with chronic pain, who also have evidence of hazardous opioid use. To examine this aim, a random design was used to assess the feasibility and initial efficacy of integrating 2 empirically supported interventions: Acceptance and Commitment Therapy for chronic pain and Mindfulness Based Relapse Prevention for opioid misuse. Half of participants were randomized to the integrated treatment group and all participants received usual care through a Veteran's Administration co-occurring disorders medical clinic to treat chronic pain and opioid misuse. In total, 37 participants were randomized and included in intent-to-treat analyses and 32 individuals were included in per protocol analyses with 6-month follow-up serving as the primary study endpoint. Feasibility indicators included recruitment, retention, and treatment completion rates. Recruitment fell short of targeted enrollment, although retention and completion were excellent. Primary outcome measures were opioid misuse, pain interference, and pain behavior. Simultaneous multiple regression analyses controlled for pain duration, baseline opioid dose, and baseline value for outcome measures. Results of both the intent-to-treat and per protocol indicated a significant effect in favor of the integrated intervention for opioid misuse, pain interference, and pain behavior. Results support the feasibility of providing an integrated treatment for both opioid risk and pain interference. PERSPECTIVE: Opioid misuse occurs in some opioid-prescribed individuals with chronic pain. Few treatment options exist that target both pain interference and opioid misuse. This study examined feasibility and initial efficacy of an integrated behavioral treatment for Veterans. Feasibility was supported, except recruitment. Efficacy was supported compared to usual care.

A Mini-Review of the Role of Glutamate Transporter in Drug Addiction

Goals: The development of new treatment for drug abuse requires identification of targetable molecular mechanisms. The pathology of glutamate neurotransmission system in the brain reward circuit is related to the relapse of multiple drugs. Glutamate transporter regulates glutamate signaling by removing excess glutamate from the synapse. And the mechanisms between glutamate transporter and drug addiction are still unclear.

Methods: A systematic review of the literature searched in Pubmed and reporting drug addiction in relation to glutamate transporter. Studies were screened by title, abstract, and full text.

Results: This review is to highlight the effects of drug addiction on glutamate transporter and glutamate uptake, and targeting glutamate transporter as an addictive drug addiction treatment. We focus on the roles of glutamate transporter in different brain regions in drug addiction. More importantly, we suggest the functional roles of glutamate transporter may prove beneficial in the treatment of drug addiction.

Conclusion: Overall, understanding how glutamate transporter impacts central nervous system may provide a new insight for treatment of drug addiction.

Nociceptive-like behavior and analgesia in silver catfish (Rhamdia quelen)

Fish are useful animal models in research and have been employed in developing new pharmacological approaches. This study aimed to establish the use of silver catfish (Rhamdia quelen) as an animal model to evaluate antinociceptive activity. Initially, different concentrations of acetic acid (2.5-20%), formalin 1% (1-10 μL), menthol 0.5% (1-10 μL) or vehicle were injected in the lips to establish which concentration of each sample promotes nociceptive-like behavior in various parameters. The effect of morphine (0.5-10 mg/kg) on locomotion parameters was also evaluated for antinociceptive concentration determination. Morphine was administered intramuscularly immediately prior to algogen administration. The inhibition was evaluated with the antagonist naloxone (5 mg/kg), which was administered in the same way. Recording time varied according to the algogen used in each test and locomotor activity was evaluated by ANY-maze® software. Acid acetic at 15%, 10 μL of 1% formalin, and 1 μL of 0.5% menthol were chosen since they promoted nociceptive-like behavior in several parameters. Morphine (5 mg/kg) reversed the algogen-induced nociceptive-like behavior and naloxone inhibited this effect. Therefore, the proposed experimental model demonstrated specificity for nociception, since the reversion of the nociceptive-like behavior for a compound with well-described analgesic activity was observed. This new pharmacological model contributes to evaluating compounds with analgesic potential and developing new analgesic drugs, in addition to being a promising alternative to use with rodents.

Using Analgesics for Emotional Modulation is Associated With Increased Distress, Depression, and Risk of Opioid and Alcohol Misuse: Initial Evaluation and Component Analysis of the Reasons for Analgesic Use Measure (RAUM)

OBJECTIVES

It is important to identify aspects of analgesic use that are associated with harm in chronic pain. Historically, the focus has been patterns of use (eg, overuse). This study evaluated another aspect of use-rather than evaluating how analgesics were being used, the primary interest was in why they were being used.

METHODS

In total, 334 analgesic using individuals with chronic pain responded to a pool of items assessing reasons for analgesic use. Measures of pain intensity, distress, depression, and opioid and alcohol misuse were also completed.

RESULTS

Exploratory factor analyses indicated 3 overarching reasons for use, including taking analgesics: (1) for pain reduction/functional improvement; (2) for emotional modulation/sedation; and (3) to be compliant with prescriber instructions. Correlation and regression analyses indicated that the second factor had the strongest relations with the other measures used, such that greater endorsement of analgesic use for emotional modulation was associated with greater distress, depression, and opioid and alcohol misuse. Using analgesics for pain reduction/functional improvement was associated with greater pain-related distress and depression. Using analgesics to be compliant was not associated with any measure. This pattern of results was generally replicated when a subsample of 131 individuals taking opioids was examined.

DISCUSSION

Results support the utility of examining reasons for analgesic use; use to achieve emotional modulation/sedation may be particularly associated with risk. The data also provide support for the questionnaire developed, the Reasons for Analgesic Use Measure.

Clinical Strategies for the Treatment and Management of Patients Prescribed Long-term Opioid Therapy

OBJECTIVES

Across diverse health care systems, growing recognition of the harms associated with long-term opioid therapy (LTOT) for chronic pain has catalyzed substantial changes to policy and practice designed to promote safer prescribing and patient care. Although clear goals have been defined, how clinics and providers should most effectively implement these changes has been less well defined, and facilities and providers have had substantial flexibility to innovate.

METHODS

Qualitative interviews were conducted with 24 Department of Veterans Affairs (VA) clinicians across the United States who prescribe LTOT for chronic pain. Interviews probed the practices and initiatives providers utilized to meet opioid safety requirements and address common challenges in caring for patients prescribed LTOT.

RESULTS

Innovative strategies in the design and organization of clinical practice (urine drug testing, informed consent, limiting transfer requests, specialty patient panel) and resources utilized (engaged pharmacists, non-opioid pain treatments, intra-organizational collaborations) are described.

CONCLUSIONS

We conclude with recommendations designed to improve opioid prescribing practices, both within the VA and in other settings.

What Do Providers Want from a Pain Screening Measure Used in Daily Practice?

Objectives

We aimed to understand providers' experiences and preferences regarding several brief pain screening measures.

Methods

We collected two waves of data for this analysis. Wave one: We conducted nine focus groups with multidisciplinary Department of Veterans Affairs (VA) providers. Wave two: To understand an emergent theme in wave one, we conducted 15 telephone interviews with prescribing providers where we used a semistructured guide comparing screening measures currently used in VA practices. Using content analysis of the wave two interviews, we evaluated providers' perceptions of important aspects of brief pain screening measures and reported emergent themes.

Results

Five emergent themes underlie providers' perceptions of the utility of brief pain screening measures: 1) item abstractness: how bounded and concrete a patient's interpretation of an individual item is; 2) item distinctness: belief in the patient's ability to differentiate between the meaning of various items in a pain measure; 3) item anchoring: presence of a description under each response option making the meaning explicit; 4) item look-back period: the period of time over which patients are asked to remember and comment on their pain; 5) parsimony: identifying the shortest and simplest approach possible to acquire desired information.

Conclusions

Overly complex or adaptive screening tools may include information that is ultimately not used by providers. Conversely, overly simplistic pain screening tools may omit information that helps providers understand the impact of pain on patients' lives. As pain is nuanced, complex, and subjective, all screening measures exhibit some limitations. No single pain measure serves all chronic pain patients, and specific contexts or settings may warrant additional specific items.

Complementary and Integrated Health Approaches: What Do Veterans Use and Want

OBJECTIVES

Non-pharmacological treatment options for common conditions such as chronic pain, anxiety, and depression are being given increased consideration in healthcare, especially given the recent emphasis to address the opioid crisis. One set of non-pharmacological treatment options are evidence-based complementary and integrative health (CIH) approaches, such as yoga, acupuncture, and meditation. The Veterans Health Administration (VHA), the nation's largest healthcare system, has been at the forefront of implementing CIH approaches, given their patients' high prevalence of pain, anxiety, and depression. We aimed to conduct the first national survey of veterans' interest in and use of CIH approaches.

METHODS

Using a large national convenience sample of veterans who regularly use the VHA, we conducted the first national survey of veterans' interest in, frequency of and reasons for use of, and satisfaction with 26 CIH approaches (n = 3346, 37% response rate) in July 2017.

RESULTS

In the past year, 52% used any CIH approach, with 44% using massage therapy, 37% using chiropractic, 34% using mindfulness, 24% using other meditation, and 25% using yoga. For nine CIH approaches, pain and stress reduction/relaxation were the two most frequent reasons veterans gave for using them. Overall, 84% said they were interested in trying/learning more about at least one CIH approach, with about half being interested in six individual CIH approaches (e.g., massage therapy, chiropractic, acupuncture, acupressure, reflexology, and progressive relaxation). Veterans appeared to be much more likely to use each CIH approach outside the VHA vs. within the VHA.

CONCLUSIONS

Veterans report relatively high past-year use of CIH approaches and many more report interest in CIH approaches. To address this gap between patients' level of interest in and use of CIH approaches, primary care providers might want to discuss evidence-based CIH options to their patients for relevant health conditions, given most CIH approaches are safe.

Opioid maintenance, weaning and detoxification techniques; where we have been, where we are now and what the future holds: an update

In 2017, the US Department of Health and Human Services declared a public health emergency on the opioid crisis. On average, 115 Americans die each day from an opioid overdose. The scope and breadth of this problem is continually evolving. In 2010, there was a shift in causes primarily due to the use of heroin, and currently the latest shift in opioid-related deaths involves a variety of synthetic opioids, particularly illicitly manufactured fentanyl. As the medical, sociological and political environments have drastically changed, especially in the USA, over the last 6 years with regard to opioid use and misuse, an updated review of the literature was necessary.

Systematic Review of Pain Medicine Content, Teaching, and Assessment in Medical School Curricula Internationally

Introduction

Pain management is a major health care challenge in terms of the significant prevalence of pain and the negative consequences of poor management. Consequently, there have been international calls to improve pain medicine education for medical students. This systematic review examines the literature on pain medicine education at medical schools internationally, with a particular interest in studies that make reference to: a defined pain medicine curriculum, specific pain medicine learning objectives, dedicated pain education modules, core pain topics, medical specialties that teach pain medicine, elective study opportunities, hours allocated to teaching pain medicine during the curriculum, the status of pain medicine in the curriculum (compulsory or optional), as well as teaching, learning, and assessment methods.

Methods

A systematic review was undertaken of relevant studies on pain medicine education for medical students published between January 1987 and May 2018 using PubMed, Medline, Excerpta Medica database (EMBASE), Education Resources Information Center (ERIC), and Google Scholar, and Best Evidence Medical Education (BEME) data bases.

Results

Fourteen studies met the inclusion criteria. Evaluation of pain medicine curricula has been undertaken at 383 medical schools in Australia, New Zealand, the United States of America (USA), Canada, the United Kingdom (UK), and Europe. Pain medicine was mostly incorporated into medical courses such as anaesthesia or pharmacology, rather than presented as a dedicated pain medicine module. Ninety-six percent of medical schools in the UK and USA, and nearly 80% of medical schools in Europe had no compulsory dedicated teaching in pain medicine. On average, the median number of hours of pain content in the entire curriculum was 20 in Canada (2009), 20 in Australia and New Zealand (2018), 13 in the UK (2011), 12 in Europe (2012/2013), and 11 in the USA (2009). Neurophysiology and pharmacology pain topics were given priority by medical schools in all countries. Lectures, seminars, and case-based instruction were the teaching methods most commonly employed. When it was undertaken, medical schools mostly assessed student competency in pain medicine using written examinations rather than clinical assessments.

Conclusions

This systematic review has revealed that pain medicine education at medical schools internationally does not adequately respond to societal needs in terms of the prevalence and public health impact of inadequately managed pain.

Electronic supplementary material

The online version of this article (10.1007/s40122-018-0103-z) contains supplementary material, which is available to authorized users.

Association Between Prescription Drug Monitoring Programs and Nonfatal and Fatal Drug Overdoses: A Systematic Review

Background

Prescription drug monitoring programs (PDMPs) are a key component of the president's Prescription Drug Abuse Prevention Plan to prevent opioid overdoses in the United States.

Purpose

To examine whether PDMP implementation is associated with changes in nonfatal and fatal overdoses; identify features of programs differentially associated with those outcomes; and investigate any potential unintended consequences of the programs.

Data Sources

Eligible publications from MEDLINE, Current Contents Connect (Clarivate Analytics), Science Citation Index (Clarivate Analytics), Social Sciences Citation Index (Clarivate Analytics), and ProQuest Dissertations indexed through 27 December 2017 and additional studies from reference lists.

Study Selection

Observational studies (published in English) from U.S. states that examined an association between PDMP implementation and nonfatal or fatal overdoses.

Data Extraction

2 investigators independently extracted data from and rated the risk of bias (ROB) of studies by using established criteria. Consensus determinations involving all investigators were used to grade strength of evidence for each intervention.

Data Synthesis

Of 2661 records, 17 articles met the inclusion criteria. These articles examined PDMP implementation only (n = 8), program features only (n = 2), PDMP implementation and program features (n = 5), PDMP implementation with mandated provider review combined with pain clinic laws (n = 1), and PDMP robustness (n = 1). Evidence from 3 studies was insufficient to draw conclusions regarding an association between PDMP implementation and nonfatal overdoses. Low-strength evidence from 10 studies suggested a reduction in fatal overdoses with PDMP implementation. Program features associated with a decrease in overdose deaths included mandatory provider review, provider authorization to access PDMP data, frequency of reports, and monitoring of nonscheduled drugs. Three of 6 studies found an increase in heroin overdoses after PDMP implementation.

Limitation

Few studies, high ROB, and heterogeneous analytic methods and outcome measurement.

Conclusion

Evidence that PDMP implementation either increases or decreases nonfatal or fatal overdoses is largely insufficient, as is evidence regarding positive associations between specific administrative features and successful programs. Some evidence showed unintended consequences. Research is needed to identify a set of "best practices" and complementary initiatives to address these consequences.

Primary Funding Source

National Institute on Drug Abuse and Bureau of Justice Assistance.

Ondansetron Does Not Reduce Withdrawal in Patients With Physical Dependence on Chronic Opioid Therapy

OBJECTIVES

Individuals taking opioids for an extended period of time may become physically dependent, and will therefore experience opioid withdrawal should they stop taking the medication. Previous work in animal and human models has shown that the serotonin (5-HT3) receptor may be implicated in opioid withdrawal. In this study, we investigated if ondansetron, a 5-HT3-receptor antagonist, could reduce the symptoms of opioid withdrawal after chronic opioid exposure in humans.

METHODS

In this double-blinded, randomized, crossover study, 33 chronic back pain patients (N = 33) were titrated onto sustained-release oral morphine for 30 days. After titration, participants attended 2 study sessions, 1 week apart, in which opioid withdrawal was induced with intravenous naloxone, with or without 8 mg intravenous ondansetron pretreatment. Opioid withdrawal symptoms were assessed by a blinded research assistant (objective opioid withdrawal score [OOWS]) and by the research participant (subjective opioid withdrawal score [SOWS]).

RESULTS

Clinically significant signs of withdrawal were observed during both the ondansetron (ΔOOWS = 3.58 ± 2.22, P < 0.0001; ΔSOWS = 12.48 ± 11.18, P < 0.0001) and placebo sessions (ΔOOWS = 3.55 ± 2.39, P < 0.0001; ΔSOWS = 12.21 ± 10.72, P < 0.0001), but no significant differences were seen between the treatment sessions in either the OOWS or SOWS scores.

CONCLUSION

We hypothesized that ondansetron would reduce opioid withdrawal symptoms in human subjects, but found no difference in withdrawal severity between ondansetron and placebo sessions. These findings suggest that more investigation may be necessary to determine if 5-HT3-receptor antagonists are suitable treatment options for opioid withdrawal.

Pain medicine content, teaching and assessment in medical school curricula in Australia and New Zealand

BACKGROUND

The objective of pain medicine education is to provide medical students with opportunities to develop their knowledge, skills and professional attitudes that will lead to their becoming safe, capable, and compassionate medical practitioners who are able to meet the healthcare needs of persons in pain. This study was undertaken to identify and describe the delivery of pain medicine education at medical schools in Australia and New Zealand.

METHOD

All 23 medical schools in Australia and New Zealand in 2016 were included in this study. A structured curriculum audit tool was used to obtain information on pain medicine curricula including content, delivery, teaching and assessment methods.

RESULTS

Nineteen medical schools (83%) completed the curriculum audit. Neurophysiology, clinical assessment, analgesia use and multidimensional aspects of pain medicine were covered by most medical schools. Specific learning objectives for pain medicine were not identified by 42% of medical schools. One medical school offered a dedicated pain medicine module delivered over 1 week. Pain medicine teaching was delivered at all schools by a number of different departments throughout the curriculum. Interprofessional learning (IPL) in the context of pain medicine education was not specified by any of the medical schools. The mean time allocated for pain medicine teaching over the entire medical course was just under 20 h. The objective structured clinical examination (OSCE) was used by 32% of schools to assess knowledge and skills in pain medicine. 16% of schools were unsure of whether any assessment of pain medicine education took place.

CONCLUSION

This descriptive study provides important baseline information for pain medicine education at medical schools in Australia and New Zealand. Medical schools do not have well-documented or comprehensive pain curricula that are delivered and assessed using pedagogically-sound approaches considering the complexity of the topic, the prevalence and public health burden of pain.

The Relationship Between Chronic Pain and Neurocognitive Function: A Systematic Review

OBJECTIVE

Understanding the relationship between chronic pain and neurocognition has important implications for the assessment and treatment of patient experiencing pain. This paper provides an overview of the current literature examining the neurocognition-chronic pain relationship and suggests future avenues of research, along with a discussion of clinical implications of the literature findings. Consideration of potential moderators and mediators of this relationship, as well as a brief discussion of the importance of future research in special populations at particular risk for these problems, are also a focus of this paper.

METHODS

This systematic review summarizes the findings of clinical studies in which neurocognitive performance was measured in chronic pain samples. A literature search led to the inclusion of 53 articles in the review.

RESULTS

Studies of neurocognitive performance in clinical chronic pain samples support a relationship between chronic pain and neurocognitive abnormalities, particularly on tests of memory, attention, and processing speed, with mixed data regarding executive functioning.

DISCUSSION

Several factors may moderate or mediate the relationship between chronic pain and neurocognitive functioning, including mood symptoms, medication side effects, and intensity and/or chronicity of pain. Limitations in the literature include a paucity of methodologically rigorous studies controlling for confounding variables (eg, opioid analgesia) and a limited number of studies examining the relationship between chronic pain and traumatic brain injury (a potential precipitant of both pain and neurocognitive impairment). Nonetheless, findings from the existing literature have significant clinical implications, including for populations with heightened risk of both pain and neurocognitive disorders.

Long-acting intramuscular naltrexone for opioid use disorder: Utilization and association with multi-morbidity nationally in the Veterans Health Administration

BACKGROUND

Long acting intramuscular (IM) naltrexone is an effective treatment for opioid use disorder (OUD), but rates and correlates of its use have not been studied.

METHODS

National administrative from the Veterans Health Administration (VHA) from Fiscal Year 2012 identified only 16 VHA facilities that prescribed IM naltrexone to 5 or more veterans diagnosed with OUD. Data from these facilities were used to identify sociodemographic, diagnostic, and service use characteristics, including use of psychotropic medication, that were characteristic of veterans who filled prescriptions for IM naltrexone. This was in comparison to users of opiate agonist treatments (methadone or buprenorphine) or veterans with no pharmacologic treatment for OUD. Comparisons were made using both bi-variate analyses and multivariable logistic regression.

RESULTS

Only 179 of 16,402 veterans with OUD (1%) at these 16 facilities filled a prescription for IM naltrexone and only 256 of 99,394 (0.26%) nationally. These veterans were characterized by past homelessness, co-morbid alcohol use disorder, multiple psychiatric disorders, and a greater likelihood of psychiatric hospitalization, as well as mental health outpatient and antidepressant medication use.

CONCLUSIONS

IM naltrexone is rarely used for OUD and is primarily used for patients with multiple co-morbidities, especially alcohol use disorder and serious mental illness. The use of this treatment illustrates many of the principles identified by the emerging focus on multi-morbidity as a critical feature of clinical practice.

The Genetics of Pain: Implications for Therapeutics

Pain is an increasing clinical challenge affecting about half the population, with a substantial number of people suffering daily intense pain. Such suffering can be linked to the dramatic rise in opioid use and associated deaths in the United States. There is a pressing need for new analgesics with limited side effects. Here, we summarize what we know about the genetics of pain and implications for drug development. We make the case that chronic pain is not one but a set of disease states, with peripheral drive a key element in most. We argue that understanding redundancy and plasticity, hallmarks of the nervous system, is critical in developing analgesic drug strategies. We describe the exploitation of monogenic pain syndromes and genetic association studies to define analgesic targets, as well as issues associated with animal models of pain. We appraise present-day screening technologies and describe recent approaches to pain treatment that hold promise.

Characteristics of Chronic Pain Patients Attending a Primary Health Care Center in Oman

Objectives

To determine the characteristics of patients presenting with chronic pain in a primary health care setting in Oman.

Methods

A retrospective cross-sectional study was carried out including all patients aged ≥ 18 years who attended Sultan Qaboos University Health Center during 2010. Patients were identified to have chronic pain if they were prescribed an analgesic medication for at least three months. Patients were compared to a control group which consisted of age- and gender-matched patients with no chronic pain.

Results

Out of 6 609 patients, 241 (3.6%) were found to have chronic pain. The mean age of patients with chronic pain was 54.0±13.0 years. The majority of patients were female (n = 174; 72.1%), and most were Omani (n = 201; 83.4%). The prevalence of chronic pain was found to be significantly higher among females compared to males (4.5% vs. 2.5%; p < 0.001) and also among Omani nationals to non-nationals (83.4% vs. 70.1%; p < 0.001). Chronic pain was significantly associated with the following comorbidities; diabetes (33.1% vs. 20.7%; p < 0.001), obesity (35.2% vs. 26.5%; p = 0.001), and hypertension (51.0% vs. 38.5%; p = 0.002). Osteoarthritis was the most common pain condition (n = 104; 43.1%). Diclofenac was the most commonly prescribed drug (n = 168; 69.7%).

Conclusions

The findings of our study point towards a higher prevalence of chronic pain in Omani females. These patients were also found to have a higher prevalence of other common comorbid conditions.

Trends in diagnosis of painful neck and back conditions, 2002 to 2011

Neck and back pain are pervasive problems. Some have suggested that rising incidence may be associated with the evidence of rising prevalence.To describe the trends in diagnosis of painful neck and back conditions in a large national healthcare system.A retrospective observational cohort study to describe the incidence and prevalence of diagnosis of neck and back pain in a national cohort.Patients were identified by International Classification of Diseases, 9 Revision (ICD-9) codes in Department of Veterans Affairs (VA) national utilization datasets in calendar years 2002 to 2011.Descriptive statistics were used to analyze the data. Prevalent cases were compared with all veterans who sought health care in each year. Incident cases were identified following a 2 years clean period in which the patient was enrolled and received care, but not services for any back or neck pain conditions.From 2004 to 2011, 3% to 4% of the population was diagnosed with incident back pain problems, the rate increasing on average, 1.75% per year. During the same period, 12.3% to 16.2% of the population was diagnosed with a prevalent back pain problem, the rate increasing on average 4.09% per year.In a national population, the prevalence rate for diagnosis of neck and back pain grew 1.8 to 2.3 times faster than the incidence rate. This suggests that the average duration of episodes of care is increasing. Additional research is needed to understand the influences on the differential rate of change and to develop efficient and effective care systems.

A Double-Blind Placebo Randomized Controlled Trial of Minocycline to Reduce Pain After Carpal Tunnel and Trigger Finger Release

PURPOSE

Minocycline is a microglial cell inhibitor and decreases pain behaviors in animal models. Minocycline might represent an intervention for reducing postoperative pain. This trial tested whether perioperative administration of minocycline reduced time to pain resolution (TPR) after standardized hand surgeries with known prolonged pain profiles: carpal tunnel release (CTR) and trigger finger release (TFR).

METHODS

This double-blinded randomized controlled trial included patients undergoing CTR or TFR under local anesthesia. Before surgery, participants recorded psychological and pain measures. Participants received oral minocycline, 200 mg, or placebo 2 hours prior to procedure, and then 100 mg of minocycline or placebo 2 times a day for 5 days. After surgery, participants were called daily assessing their pain. The primary end point of TPR was when participants had 3 consecutive days of 0 postsurgical pain. Futility analysis and Kaplan-Meier analyses were performed.

RESULTS

A total of 131 participants were randomized and 56 placebo and 58 controls were analyzed. Median TPR for CTR was 3 weeks, with 15% having pain more than 6 weeks. Median TPR for TFR was 2 weeks with 18% having pain more than 6 weeks. The overall median TPR for the placebo group was 2 weeks (10% pain > 6 weeks) versus 2.5 weeks (17% pain > 6 weeks) for the minocycline group. Futility analysis found that the likelihood of a true underlying clinically meaningful reduction in TPR owing to minocycline was only 3.5%. Survival analysis found minocycline did not reduce TPR. However, subgroup analysis of those with elevated posttraumatic distress scores found the minocycline group had longer TPR.

CONCLUSIONS

Oral administration of minocycline did not reduce TPR after minor hand surgery. There was evidence that minocycline might increase length of pain in those with increased posttraumatic stress disorder symptoms.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic I.

Clinical Usefulness of Long-term Application of Fentanyl Matrix in Chronic Non-Cancer Pain: Improvement of Pain and Physical and Emotional Functions

BACKGROUND

Opioids are recently recommended for those who do not gain adequate pain relief from the use of acetaminophen or nonsteroidal anti-inflammatory drugs. Medical opioids are administered in various routes, and transdermal opioid products that can make up for the weaknesses of the oral or intravenous products have been developed. This study is to evaluate the clinical usefulness of fentanyl matrix in terms of the long-term improvement in pain and physical and mental functions.

METHODS

This was a multicenter, open, prospective, observational study that was conducted in 54 institutions in Korea. Patients with non-cancerous chronic pain completed questionnaires, and investigators also completed questionnaires. A total of 1,355 subjects participated in this study, and 639 subjects completed the study. Subjects received transdermal fentanyl matrix (12 µg/hr, 25 µg/hr, or 50 µg/hr depending on the patient's response and demand). Subjects visited at 29 ± 7 days, 85 ± 14 days, and 169 ± 14 days after administration, respectively, to receive drug titration and fill out the questionnaires. The results were analyzed using the intention-to-treat (ITT) analysis, full analysis set (FAS), and per-protocol (PP) analysis. The FAS analysis included only 451 participants; the PP analysis, 160 participants; and the ITT analysis, 1,355 participants.

RESULTS

The intensity of pain measured by the Numeric Rating Scale decreased from 7.07 ± 1.78 to 4.93 ± 2.42. The physical assessment score and mental assessment score of the Short-Form Health Survey 12 improved from 28.94 ± 7.23 to 35.90 ± 10.25 and from 35.80 ± 11.76 to 42.52 ± 10.58, respectively. These differences were significant, and all the other indicators also showed improvement. Adverse events with an incidence of ≥ 1% were nausea, dizziness, vomiting, and pruritus.

CONCLUSIONS

The long-term administration of fentanyl matrix in patients with non-cancerous pain can reduce the intensity of pain and significantly improves activities of daily living and physical and mental capabilities.

Changes in Prevalence, Outcomes, and Help-seeking Behavior of Chronic Pain in an Aging Population Over the Last Decade

BACKGROUND

Chronic pain is expected to increase as the population ages. This study aimed to investigate the changes in prevalence, patterns, and help-seeking behavior of chronic pain and prevalence of neuropathic pain of an aging population in Hong Kong.

METHODS

A cross-sectional, telephone interview with a structured questionnaire was conducted in a randomly selected sample of adults with acute or chronic pain of any kind in the general population to estimate the prevalence of chronic and neuropathic pain, and to describe sociodemographics and help-seeking behavior. Results were compared with a similar study conducted in 1999.

RESULTS

Totally, 1,570 people were interviewed. Chronic pain was experienced by 28.7% of all respondents, compared to 10.8% in 1999. Joint (45.5%), muscle (27.1%), and back (25.2%) pain were the most common, similar to findings in 1999. Of those with chronic pain, 83.1% reported pain in more than one body site (63.4% in 1999, P = 0.0023). More respondents reported their average pain as being intense (51.57% vs. 33.0% in 2013 and 1999, respectively, P = 0.0098). A downward trend of respondents taking medications for chronic pain (34.9% in 2013 vs. 47.6% in 1999, P = 0.019) was seen. Neuropathic pain was present in 9.03% of the population and 14.7% of chronic pain sufferers.

CONCLUSION

The prevalence of neuropathic pain in Hong Kong is high and is described here for the first time. The number of chronic pain sufferers has tripled in the past decade. Significant changes in the patterns and help- seeking behavior of chronic pain sufferers are also seen.

Brain Reward Circuits in Morphine Addiction

Morphine is the most potent analgesic for chronic pain, but its clinical use has been limited by the opiate's innate tendency to produce tolerance, severe withdrawal symptoms and rewarding properties with a high risk of relapse. To understand the addictive properties of morphine, past studies have focused on relevant molecular and cellular changes in the brain, highlighting the functional roles of reward-related brain regions. Given the accumulated findings, a recent, emerging trend in morphine research is that of examining the dynamics of neuronal interactions in brain reward circuits under the influence of morphine action. In this review, we highlight recent findings on the roles of several reward circuits involved in morphine addiction based on pharmacological, molecular and physiological evidences.

Opioid-induced bowel dysfunction: epidemiology, pathophysiology, diagnosis, and initial therapeutic approach

Opioids affect motor and sensory function throughout the gastrointestinal tract, and are frequently associated with a number of gastrointestinal symptoms including constipation, which impairs the quality of life and may limit the dose of opioid or result in discontinuation altogether. Patients with opioid-induced constipation should be assessed by careful history and physical examination, and in some cases where the diagnosis is unclear with select diagnostic tests. Few clinical studies have been conducted to assess the efficacy of various treatments. However, it is generally recommended that first-line therapy begin with opioid rotation, as well as with low-cost and low-risk approaches such as lifestyle changes, consumption of fiber-rich food, stool softeners, and laxatives.

Differential expression of P2X7 receptor and IL-1β in nociceptive and neuropathic pain

BACKGROUND

Despite substantial progress, pathogenesis and therapy of chronic pain are still the focus of many investigations. The ATP-gated P2X7 receptor (P2X7R) has previously been shown to play a central role in animal models of nociceptive inflammatory and neuropathic pain. Recently, we found that the adaptive immune system is involved in the pathophysiology of chronic nociceptive and neuropathic pain in humans. So far, data regarding P2X7R expression patterns on cells of the adaptive immune system of pain patients are scarce. We therefore analyzed the P2X7R expression on peripheral blood lymphocytes and monocytes, as well as serum levels of IL-1β in patients suffering from chronic nociceptive and neuropathic pain in comparison to healthy volunteers in order to identify individuals who might benefit from a P2X7R modulating therapy.

METHODS

P2X7R messenger RNA (mRNA) and protein expression were determined in patients with either chronic nociceptive low back pain (CLBP) or neuropathic pain (NeP), and in healthy volunteers by quantitative real-time PCR (qPCR) and by fluorescence-assisted cell-sorting (FACS), respectively. IL-1β serum levels were measured with a multiplex cytokine assay.

RESULTS

Compared to healthy volunteers, P2X7R mRNA (1.6-fold, p = 0.038) and protein levels were significantly increased on monocytes (NeP: 24.6 ± 6.2, healthy volunteers: 17.0 ± 5.4; p = 0.002) and lymphocytes (NeP: 21.8 ± 6.5, healthy volunteers: 15.6 ± 5.2; p = 0.009) of patients with NeP, but not in patients with CLBP. Similarly, IL-1β serum concentrations were significantly elevated only in NeP patients (1.4-fold, p = 0.04).

CONCLUSIONS

A significant upregulation of P2X7R and increased IL-1β release seems to be a particular phenomenon in patients with NeP. P2X7R inhibitors may therefore represent a potential option for the treatment of this frequently intractable type of pain. German Clinical Trial Register (DRKS): Registration Trial DRKS00005954.

Predictors of Improvements in Pain Intensity in a National Cohort of Older Veterans With Chronic Pain

Little is known about the factors associated with pain-related outcomes in older adults. In this observational study, we sought to identify patient factors associated with improvements in pain intensity in a national cohort of older veterans with chronic pain. We included 12,924 veterans receiving treatment from the Veterans Health Administration with persistently elevated numeric rating scale scores in 2010 who had not been prescribed opioids in the previous 12 months. We examined: 1) percentage decrease over 12 months in average pain intensity scores relative to average baseline pain intensity score; and 2) time to sustained improvement in average pain intensity scores, defined as a 30% reduction in 3-month scores compared with baseline. Average relative improvement in pain intensity scores from baseline ranged from 25% to 29%; almost two-thirds met criteria for sustained improvement during the 12-month follow-up period. In models, higher baseline pain intensity and older age were associated with greater likelihood of improvement in pain intensity, whereas Veterans Affairs service-connected disability, mental health, and certain pain-related diagnoses were associated with lower likelihood of improvement. Opioid prescription initiation during follow-up was associated with lower likelihood of sustained improvement. The findings call for further characterization of heterogeneity in pain outcomes in older adults as well as further analysis of the relationship between prescription opioids and treatment outcomes.

PERSPECTIVE

This study identified factors associated with improvements in pain intensity in a national cohort of older veterans with chronic pain. We found that older veterans frequently show improvements in pain intensity over time, and that opioid prescriptions, mental health, and certain pain diagnoses are associated with lower likelihood of improvement.

Exposure to High-Risk Medications is Associated With Worse Outcomes in Older Veterans With Chronic Pain

BACKGROUND

Chronic pain is common, costly and leads to significant morbidity in older adults, yet there are limited data on medication safety. The authors sought to evaluate the association of incident high-risk medication in the elderly (HRME) with mortality, emergency department (ED) or hospital care among older adults with chronic pain.

METHODS

A retrospective Veterans Health Administration cohort study was conducted examining older veterans with chronic pain diagnoses and use of incident HRME (opioids, skeletal muscle relaxants, antihistamines and psychotropics). Outcomes evaluated included all-cause mortality, ED visits or inpatient hospital care. Descriptive statistics summarized variables for the overall cohort, the chronic pain cohort and those with and without HRME. Separate generalized linear mixed-effect regression models were used to examine the association of incident HRME on each outcome, controlling for potential confounders.

RESULTS

Among 1,807,404 veterans who received Department of Veterans Affairs care in 2005 to 2006, 584,066 (32.3%) had chronic pain; 45,945 veterans with chronic pain (7.9%) had incident HRME exposure. The strongest significant associations of incident HRME were for high-risk opioids with all-cause hospitalizations (odds ratio [OR] 2.08, 95% confidence interval [CI] 1.95-2.23), skeletal muscle relaxants with all-cause ED visits (OR 2.62, 95% CI 2.52-2.73) and mortality (OR 0.80, 95% CI 0.74-0.86), antihistamines with all-cause ED visits (OR 2.82 95% CI 2.72-2.95) and psychotropics with all-cause hospitalizations (OR 2.15, 95% CI 1.96-2.35).

CONCLUSIONS

Our data indicate that incident HRME is associated with clinically important adverse outcomes in older veterans with chronic pain and highlight the importance of being judicious with prescribing certain classes of drugs in this vulnerable population.