Long-term use of opioids for complex chronic pain

Does opioid therapy enhance quality of life in patients suffering from chronic non-malignant pain? A systematic review and meta-analysis

Background and objective

Chronic pain is associated with a poor health-related quality of life (HRQL). Whereas the prescription rate of opioids increased during the last decades, their use in chronic non-malignant pain remains unclear. However, there is currently no clinical consensus or evidence-based guidelines that consider the long-term effects of opioid therapy on HRQL in patients with chronic non-cancer pain. This systematic review aims to address the question of whether opioid therapy improves HRQL in patients with chronic non-malignant pain and provide some guidance to practitioners.

Databases and data treatment

PubMed, EMBASE and CENTRAL were searched in June 2020 for double-blind, randomized trials (RCTs), comparing opioid therapy to placebo and assessed a HRQL questionnaire. The review comprises a qualitative vote counting approach and a meta-analysis of the Short Form Health Survey (SF-36), EQ-5D questionnaire and the pain interference scale of the Brief pain inventory (BPI).

Results

35 RCTs were included, of which the majority reported a positive effect of opioids for the EQ-5D, the BPI and the physical component score (PCS) of the SF-36 compared to placebo. The meta-analysis of the PCS showed a mean difference of 1.82 [confidence interval: 1.32, 2.32], the meta-analysis of the EQ-5D proved a significant advantage of 0.06 [0.00, 0.12]. In the qualitative analysis of the mental component score (MCS) of the SF-36, no positive or negative trend was seen. No significant differences were seen in the MCS (MD: 0.65 [-0.43, 1.73]). A slightly higher premature dropout rate was found in the opioid group (risk difference: 0.04 [0.00, 0.07], p = .07). The body of evidence is graded as low to medium.

Conclusion

Opioids have a statistically significant, but small and clinical not relevant effect on the physical dimensions of HRQL, whereas there is no effect on mental dimensions of HRQL in patients with chronic non-malignant pain during the initial months of treatment. In clinical practice, opioid prescriptions for chronic non-cancer pain should be individually assessed as their broad efficacy in improving quality of life is not confirmed. The duration of opioid treatment should be determined carefully, as this review primarily focuses on the initial months of therapy.

Duloxetine and cognitive behavioral therapy with phone-based support for the treatment of chronic musculoskeletal pain: study protocol of the PRECICE randomized control trial

BACKGROUND

Chronic musculoskeletal pain (CMP) is the most common, disabling, and costly of all pain conditions. While evidence exists for the efficacy of both duloxetine and web-based cognitive behavioral therapy (CBT) as monotherapy, there is a clear need to consider study of treatment components that may complement each other. In addition, given the reported association between patient's adherence and treatment outcomes, strategies are needed to enhance participant's motivation to adopt and maintain continued use of newly learned pain coping skills from CBT.

METHODS

Two hundred eighty participants will be recruited from the primary care clinics of a large academic health care system in North Carolina. Participants with CMP will be randomized to one of three treatment arms: (1) combination treatment (duloxetine + web-based self-guided CBT) with phone-based motivational interviewing (MI), (2) combination treatment without phone-based MI, and (3) duloxetine monotherapy. Participants will be in the study for 24 weeks and will be assessed at baseline, week 13, and week 25. The primary outcome is the Brief Pain Inventory (BPI)-Global Pain Severity score, which combines BPI pain severity and BPI pain interference. Secondary measures include between-group comparisons in mean BPI pain severity and BPI pain interference scores. Data collection and outcome assessment will be blinded to treatment group assignment.

DISCUSSION

This randomized controlled trial (RCT) will determine if combination treatment with duloxetine and web-based CBT is superior to duloxetine monotherapy for the management of CMP. Furthermore, this RCT will determine the effectiveness of phone-based motivational interviewing in promoting the continued practice of pain coping skills, thereby enhancing treatment outcomes.

TRIAL REGISTRATION

NCT04395001 ClinicalTrials.gov. Registered on May 15, 2020.

Duloxetine and Cognitive Behavioral Therapy with Phone-based Support for the Treatment of Chronic Musculoskeletal Pain: Study Protocol of the PRECICE Randomized Control Trial

Background

Chronic musculoskeletal pain (CMP) is the most common, disabling, and costly of all pain conditions. While evidence exists for the efficacy of both duloxetine and web-based cognitive behavioral therapy (CBT) as monotherapy, there is a clear need to consider study of treatment components that may complement each other. In addition, given the reported association between patient's adherence and treatment outcomes, strategies are needed to enhance participant's motivation to adopt and maintain continued use of newly learned pain coping skills from CBT.

Methods

Two hundred eighty participants will be recruited from the primary care clinics of a large academic health care system in North Carolina. Participants with CMP will be randomized to one of 3 treatment arms: (1) combination treatment (duloxetine + web-based self-guided CBT) with phone-based motivational interviewing (MI), (2) combination treatment without phone-based MI and (3) duloxetine monotherapy. Participants will be in the study for 24 weeks and will be assessed at baseline, week 13, and week 25. The primary outcome is the Brief Pain Inventory (BPI)-Global Pain Severity score, which combines BPI pain severity and BPI pain interference. Secondary measures include between-group comparisons in mean BPI pain severity and BPI pain interference scores. Data collection and outcome assessment will be blinded to treatment group assignment.

Discussion

This randomized controlled trial (RCT) will determine if combination treatment with duloxetine and web-based CBT is superior to duloxetine monotherapy for the management of CMP. Furthermore, this RCT will determine the effectiveness of phone-based motivational interviewing in promoting the continued practice of pain coping skills; thereby, enhancing treatment outcomes.

Trial Registration

NCT04395001. Registered in ClinicalTrials.gov on May 15, 2020.

Burden of Chronic and Heavy Opioid Use Among Elderly Community Dwellers in the U.S

Introduction

Opioid overprescribing may fuel the opioid epidemic and increase the risk of complications of opioid misuse. This study examined trends and determinants of chronic and heavy opioid use among elderly community dwellers in the U.S.

Methods

Medicare Current Beneficiary Surveys data from 2006 to 2019 were used. Common opioid medications were identified in the prescription medication files (n=47,264). Patients with Chronic users were defined as those receiving 6 or more opioid prescriptions within a year or on medication for 3 or more months, and heavy users were those having an average daily dose of 90 or more morphine milligram equivalents or 3,780 morphine milligram equivalents or more per continuous treatment episode.

Results

One in 6 elderly community dwellers ever used opioids during the study period. Chronic users were more likely to be women than men (68.9% vs 31.1%, p<0.001). Of all survey participants, 4.3% were chronic users, and 2.8% were heavy users. Among ever users, 27.7% were chronic users, and 18.1% were heavy users. The rate of opioid use rose from 12.1% in 2006, peaked at 22.8% in 2013, and decreased to 11.7% in 2019. Chronic use was 5.1%, 10.7%, and 7.6%, respectively. Heavy use was 5.5%, 10.7%, and 7.6%, respectively. However, for chronic and heavy users, there was no significant difference in the median opioid dosage and opioid duration between males and females.

Conclusions

Among elderly Medicare beneficiaries, opioid prescriptions have been decreasing since 2013. However, a substantial number of elderly people were chronic and heavy users, calling for better opioid management among them.

Precision, integrative medicine for pain management in sickle cell disease

Sickle cell disease (SCD) is a prevalent and complex inherited pain disorder that can manifest as acute vaso-occlusive crises (VOC) and/or chronic pain. Despite their known risks, opioids are often prescribed routinely and indiscriminately in managing SCD pain, because it is so often severe and debilitating. Integrative medicine strategies, particularly non-opioid therapies, hold promise in safe and effective management of SCD pain. However, the lack of evidence-based methods for managing SCD pain hinders the widespread implementation of non-opioid therapies. In this review, we acknowledge that implementing personalized pain treatment strategies in SCD, which is a guideline-recommended strategy, is currently fraught with limitations. The full implementation of pharmacological and biobehavioral pain approaches targeting mechanistic pain pathways faces challenges due to limited knowledge and limited financial and personnel support. We recommend personalized medicine, pharmacogenomics, and integrative medicine as aspirational strategies for improving pain care in SCD. As an organizing model that is a comprehensive framework for classifying pain subphenotypes and mechanisms in SCD, and for guiding selection of specific strategies, we present evidence updating pain research pioneer Richard Melzack's neuromatrix theory of pain. We advocate for using the updated neuromatrix model to subphenotype individuals with SCD, to better select personalized multimodal treatment strategies, and to identify research gaps fruitful for exploration. We present a fairly complete list of currently used pharmacologic and non-pharmacologic SCD pain therapies, classified by their mechanism of action and by their hypothesized targets in the updated neuromatrix model.

Determinants of long-term opioid use in hospitalized patients

BACKGROUND

Long-term opioid use is an increasingly important problem related to the ongoing opioid epidemic. The purpose of this study was to identify patient, hospitalization and system-level determinants of long term opioid therapy (LTOT) among patients recently discharged from hospital.

DESIGN

To be eligible for this study, patient needed to have filled at least one opioid prescription three-months post-discharge. We retrieved data from the provincial health insurance agency to measure medical service and prescription drug use in the year prior to and after hospitalization. A multivariable Cox Proportional Hazards model was utilized to determine factors associated with time to the first LTOT occurrence, defined as time-varying cumulative opioid duration of ≥ 60 days.

RESULTS

Overall, 22.4% of the 1,551 study patients were classified as LTOT, who had a mean age of 66.3 years (SD = 14.3). Having no drug copay status (adjusted hazard ratio (aHR) 1.91, 95% CI: 1.40-2.60), being a LTOT user before the index hospitalization (aHR 6.05, 95% CI: 4.22-8.68) or having history of benzodiazepine use (aHR 1.43, 95% CI: 1.12-1.83) were all associated with an increased likelihood of LTOT. Cardiothoracic surgical patients had a 40% lower LTOT risk (aHR 0.55, 95% CI: 0.31-0.96) as compared to medical patients. Initial opioid dispensation of > 90 milligram morphine equivalents (MME) was also associated with higher likelihood of LTOT (aHR 2.08, 95% CI: 1.17-3.69).

CONCLUSIONS AND RELEVANCE

Several patient-level characteristics associated with an increased risk of ≥ 60 days of cumulative opioid use. The results could be used to help identify patients who are at high-risk of continuing opioids beyond guideline recommendations and inform policies to curb excessive opioid prescribing.

Spinal Cord Stimulation to Treat Unresponsive Cancer Pain: A Possible Solution in Palliative Oncological Therapy

(1) Background: Treatment of cancer-related pain is still challenging, and it can be managed by both medical and interventional therapies. Spinal Cord Stimulation (SCS) is a minimally invasive technique, and its use is rapidly increasing in the treatment of chronic pain. (2) Materials and Methods: Our study aims to perform a review of the pertinent literature about current evidences in cancer pain treatment by Spinal Cord Stimulation. Moreover, we created a database based on case reports or case series (18 studies) in the literature. We analyzed a clinical group of oncological patients affected by intractable pain undergoing SCS implantation, focusing on outcome. (3) Results: The analysis of the 18 included studies in our series has shown a reduction in painful symptoms in 48 out of 56 treated patients (87.51%); also 53 out of 56 patients (96.64%) have shown an improvement in their Quality of Life (QoL). (4) Conclusions: Spinal Cord Stimulation can be considered an efficient method in the treatment of cancer-related pain. However, literature regarding SCS for the treatment of cancer-related pain is largely represented by case reports and small case series, with no effective population studies or Randomized Controlled Trials demonstrating the efficacy and the level of evidence. Further prospective studies are needed.

A new minisatellite VNTR marker, Pscp1, discovered for the identification of opium poppy

Opium poppy, a member of the Papaveraceae family, is an ancient herbaceous plant and well-known medical resource in the pharmaceutical industry. However, opium poppies are grown worldwide for producing illicit drugs, significantly increasing the incidence of narcotic drug abuse. Since the narcotic poppy has not yet been genetically investigated, we characterized a novel variable number tandem repeat (VNTR) marker of forensically important poppy species based on the genetic analysis of 164 samples collected from two locations spanning the Jeolla province and Jeju island of South Korea. Comparing analysis of the chloroplast (cp) genome sequences for four representative species of Papaver (Papaver somniferum, Papaver somniferum subs. setigerum, Papaver orientale, and Papaver rhoeas) revealed a unique region with 1-3 repeats for 16 nucleotide motifs in the genome inverted repeat A (IRA, positions 128,651 to 128,698) region. For 16 nucleotide motifs, 3 repeats were found in P. somniferum, and 2 repeats were found in P. somniferum subs. setigerum. Therefore, 10 known and the 133 unknown, seized Papaver species were compared to determine whether the species could be identified via variations in the repeat units. The sizes of a novel VNTR ranged from 181 to 252 bp between the species. Phylogenetic analysis confirmed that a novel VNTR, which we named Pscp1, could clearly distinguish between the narcotic and non-narcotic types of Papaver species based on the patterns of sequence variation. Interestingly, we found that Pscp1 could also distinguish between P. somniferum and P. somniferum subs. setigerum. The regions of eight non-narcotic species displayed similar patterns and also differences were found due to the nucleotide substitution and deletion events. The structural differences of Pscp1 were observed within the two narcotic species or between the narcotic and non-narcotic species, suggesting that these variations may act as a genetic marker. We, therefore, developed a new Pscp1 PCR-capillary electrophoresis (CE) method that can reliably identify the narcotic type of Papaver species. Taken together, our findings suggest that the newly developed Pscp1 can be used as an identification marker of opium poppy, and establish that the Pscp1 genotyping method by PCR-CE is an effective primary screening tool that can also contribute to species discrimination in the field of forensic diagnosis and applications.

Prevalence of long-term opioid therapy in spine center outpatients the spinal pain opioid cohort (SPOC)

PURPOSE

No reference material exists on the scope of long-term problems in novel spinal pain opioid users. In this study, we evaluate the prevalence and long-term use of prescribed opioids in patients of the Spinal Pain Opioid Cohort.

METHODS

The setting was an outpatient healthcare entity (Spine Center). Prospective variables include demographics, clinical data collected in SpineData, and The Danish National Prescription Registry. Patients with a new spinal pain episode lasting for more than two months, aged between 18 and 65 years, who had their first outpatient visit. Based on the prescription of opioids from 4 years before the first spine center visit to 5 years after, six or more opioid prescriptions in a single 1-year interval fulfilled the main outcome criteria Long-Term Opioid Therapy (LTOT).

RESULTS

Overall, of 8356 patients included in the cohort, 4409 (53%) had one or more opioid prescriptions in the registered nine years period. Of opioid users, 2261 (27%) were NaiveStarters receiving their first opioid prescription after a new acute pain episode; 2148(26%) PreStarters had previously received opioids. The prevalence of LTOT in PreStarters/NaiveStarters was 17.2%/11.2% in their first outpatient year. Similar differences between groups were seen in all follow-up intervals. In the last follow-up year, LTOT prevalence in Prestarters/NaiveStarters was 12.5%/7.0%.

CONCLUSIONS

Previous opioid treatment-i.e., before a new acute spinal pain episode and referral to a Spine Center-doubled the risk of LTOT 5 years later. The results underscore clinicians' obligation to carefully and individually weigh the benefits against the risks of prescribing opioid therapy.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Chronic Opioid Therapy: A Scoping Literature Review on Evolving Clinical and Scientific Definitions

The management of chronic noncancer pain (CNCP) with chronic opioid therapy (COT) is controversial. There is a lack of consensus on how COT is defined resulting in unclear clinical guidance. This scoping review identifies and evaluates evolving COT definitions throughout the published clinical and scientific literature. Databases searched included PubMed, Embase, and Web of Science. A total of 227 studies were identified from 8,866 studies published between January 2000 and July 2019. COT definitions were classified by pain population of application and specific dosage/duration definition parameters, with results reported according to PRISMA-ScR. Approximately half of studies defined COT as "days' supply duration >90 days" and 9.3% defined as ">120 days' supply," with other days' supply cut-off points (>30, >60, or >70) each appearing in <5% of total studies. COT was defined by number of prescriptions in 63 studies, with 16.3% and 11.0% using number of initiations or refills, respectively. Few studies explicitly distinguished acute treatment and COT. Episode duration/dosage criteria was used in 90 studies, with 7.5% by Morphine Milligram Equivalents + days' supply and 32.2% by other "episode" combination definitions. COT definitions were applied in musculoskeletal CNCP (60.8%) most often, and typically in adults aged 18 to 64 (69.6%). The usage of ">90 days' supply" COT definitions increased from 3.2 publications/year before 2016 to 20.7 publications/year after 2016. An increasing proportion of studies define COT as ">90 days' supply." The most recent literature trends toward shorter duration criteria, suggesting that contemporary COT definitions are increasingly conservative. PERSPECTIVE: This study summarized the most common, current definition criteria for chronic opioid therapy (COT) and recommends adoption of consistent definition criteria to be utilized in practice and research. The most recent literature trends toward shorter duration criteria overall, suggesting that COT definition criteria are increasingly stringent.

Long-term Opioids Linked to Hypogonadism and the Role of Testosterone Supplementation Therapy

Opioids play a pivotal role in managing chronic pain with increasing prescription rates over the last few years. Hence, it is crucial to focus on the adverse effects of narcotics, and one of the lesser-known side effects is hypogonadism. Opioids act on the hypothalamus, pituitary, and directly on the gonads affecting serum testosterone levels. Narcotic-induced androgen insufficiency contributes to sexual dysfunction, infertility, hyperalgesia, and involving various body functions overall, affecting the quality of life. Opioid-induced hypogonadism is very challenging to diagnose for the clinicians, as the patients often under-report the symptoms. There are no established guidelines to analyze androgen insufficiency and dealing with their manifestations successfully. We did a substantial search in PubMed and Google Scholar, using various combinations of keywords to collect data to evaluate the impacts of opioids on serum testosterone levels. This study aims to highlight the clinical significance of opioid-induced androgen deficiency and the diagnostic techniques to recognize and credible treatment alternatives, including testosterone replacement therapy. Health care providers should screen the patients routinely for the signs and symptoms and monitor them often for the hormonal changes to select the patients cautiously for testosterone replacement therapy.

The association between the supply of select nonpharmacologic providers for pain and use of nonpharmacologic pain management services and initial opioid prescribing patterns for Medicare beneficiaries with persistent musculoskeletal pain

OBJECTIVE

To test the relationship between the supply of select nonpharmacologic providers (physical therapy (PT) and mental health (MH)) and use of nonpharmacologic services among older adults with a persistent musculoskeletal pain (MSP) episode.

DATA SOURCES/STUDY SETTING

Claims data from a 5 percent random sample of Medicare beneficiaries enrolled fee-for-service (2007-2014) and the Area Health Resource File (AHRF).

STUDY DESIGN

This retrospective study used generalized estimating equations to estimate the association between the county nonpharmacologic provider supply and individual service use with opioid prescriptions filled during Phase 1 (first three months of an episode) and Phase 2 (three months following Phase 1).

DATA COLLECTION/EXTRACTION METHODS

We identified beneficiaries (>65 years) with ≥2 MSP diagnoses ≥90 days apart and no opioid prescription six months before the first pain diagnosis (N = 69 456). Beneficiaries' county characteristics were assigned using the AHRF.

PRINCIPAL FINDINGS

About 13.9 percent of beneficiaries used PT, 1.8 percent used MH services, and 10.7 percent had an opioid prescription during the first three months of a persistent MSP episode. An additional MH provider/10 000 people/county [aOR: 0.97, 95% CI: 0.96-0.98] and PT/10 000 people/county [aOR: 0.98, 95% CI: 0.97-1.00] was associated with lower odds of filling an opioid prescription in Phase 1. An additional MH provider/10 000 people/county [aOR: 0.97, 95% CI: 0.96-0.98] and PT use in Phase 1 [aOR: 0.62, 95% CI: 0.58-0.67] were associated with lower odds of filling an opioid prescription in Phase 2. The associations between the supply of providers and nonpharmacologic service use in Phase 1 and Phase 1 opioid prescriptions significantly differed by metropolitan and rural counties (P-value: .019).

CONCLUSIONS

Limited access to nonpharmacologic services is associated with opioid prescriptions at the onset of a persistent MSP episode. Initiating PT at the onset of an episode may reduce future opioid use. Strategies for engaging beneficiaries in nonpharmacologic services should be tailored for metropolitan and rural counties.

Long-Term Opioid Therapy in Spine Center Outpatients: Protocol for the Spinal Pain Opioid Cohort (SPOC) Study

Background

Spinal pain is the leading cause of patient-years lived with chronic pain and disability worldwide. Although opioids are well documented as an effective short-term pain-relieving medication, more than a few weeks of treatment may result in a diminishing clinical effect as well as the development of addictive behavior. Despite recognition of opioid addiction in pain patients as a major problem commonly experienced in the clinic, no reference material exists on the scope of long-term problems in novel opioid users and the link to clinical outcomes.

Objective

The main aims of this study are to describe baseline and follow-up characteristics of the Spinal Pain Opioid Cohort (SPOC), to evaluate the general use of opioids in spinal pain when an acute pain episode occurs, and to demonstrate the prevalence of long-term opioid therapy (LTOT).

Methods

Prospective clinical registry data were collected from an outpatient spine center setting during 2012-2013 including patients with a new spinal pain episode lasting for more than 2 months, aged between 18 and 65 years who had their first outpatient visit in the center. Variables include demographics, clinical data collected in SpineData, the Danish National Patient Register, and The Danish National Prescription Registry. The primary outcome parameter is long-term prescription opioid use registered from 4 years before the first spine center visit to 5 years after.

Results

This is an ongoing survey. It is estimated that more than 8000 patients fulfill the SPOC inclusion criteria. In 2019, we began the intellectual process of identifying the most relevant supplementary data available from the wide range of existing national registries available in Denmark. We have now begun merging SpineData with relevant opioid data from Danish national registers and will continue to extract data up to 2021-2022. We will also be looking at data regarding somatic or psychiatric hospitalization patterns, patient usage of health care resources, as well as their working status and disability pensions.

Conclusions

To our knowledge, this survey will be the first to document the scope of long-term problems regarding LTOT and opioid addiction following new spinal pain episodes and comparing descriptive follow-up data between substance users and nonusers.

Trial Registration

ISRCTN Registry ISRCTN69685117; http://www.isrctn.com/ISRCTN69685117

International Registered Report Identifier (IRRID)

DERR1-10.2196/21380

Long-term opioid therapy definitions and predictors: A systematic review

PURPOSE

This review sought to (a) describe definitions of long-term opioid therapy (LTOT) outcome measures, and (b) identify the predictors associated with the transition from short-term opioid use to LTOT for opioid-naïve individuals.

METHODS

We conducted a systematic review of the peer-reviewed literature (January 2007 to July 2018). We included studies examining opioid use for more than 30 days. We classified operationalization of LTOT based on criteria used in the definitions. We extracted LTOT predictors from multivariate models in studies of opioid-naïve individuals.

RESULTS

The search retrieved 5,221 studies, and 34 studies were included. We extracted 41 unique variations of LTOT definitions. About 36% of definitions required a cumulative duration of opioid use of 3 months. Only 17% of definitions considered consecutive observation periods, 27% used days' supply, and no definitions considered dose. We extracted 76 unique predictors of LTOT from seven studies of opioid-naïve patients. Common predictors included pre-existing comorbidities (21.1%), non-opioid prescription medication use (13.2%), substance use disorders (10.5%), and mental health disorders (10.5%).

CONCLUSIONS

Most LTOT definitions aligned with the chronic pain definition (pain more than 3 months), and used cumulative duration of opioid use as a criterion, although most did not account for consistent use. Definitions were varied and rarely accounted for prescription characteristics, such as days' supply. Predictors of LTOT were similar to known risk factors of opioid abuse, misuse, and overdose. As LTOT becomes a central component of quality improvement efforts, researchers should incorporate criteria to identify consistent opioid use to build the evidence for safe and appropriate use of prescription opioids.

Long-term use of hydrocodone vs. oxycodone in primary care

BACKGROUND

Hydrocodone and oxycodone are the Schedule II opioids most often prescribed in primary care. Notwithstanding the dangers of prescription opioid use, the likelihood of long-term use with either drug is presently unknown.

METHODS

Using a retrospective cohort design and data from a commerical healthcare claims repository, we compared the likelihood of long-term use of hydrocodone and oxycodone in primary care patients presenting with acute back pain. Treatment was categorized as long-term if the prescription dates spanned ≥90 days from initial prescription to the run-out date of the last prescription, and included ≥120 days' supply or ≥10 fills. Instrumental variable methods and probit regression were used to model the effect of drug choice on long-term use, estimate the average treatment effect, and correct for confounding by indication.

RESULTS

A total of 3,983 patients who were prescribed only hydrocodone or only oxycodone were followed for 270 days in 2016. Long-term opioid use was observed in 320 patients (8%). Controlling for potential confounders including morphine milligram equivalents and dosage, an estimated 12% (95 CI, 10%-14%) treated with hydrocodone transitioned to long-term use vs. 2% (95 CI, 1%-3%) on oxycodone. Among patients who received more than one prescription (n = 1,866), an estimated 23% (95 CI, 19%-26%) treated with hydrocodone transitioned to long-term use vs. 5% (95 CI, 3%-7%) on oxycodone. The difference between drugs was supported in sensitivity and subgroup analyses. Sample selection bias was not detected.

CONCLUSIONS

Long-term use was substantially greater for patients treated with hydrocodone than oxycodone, despite equianalgesia.

EULAR recommendations for the management of Sjögren’s syndrome with topical and systemic therapies

The therapeutic management of Sjögren syndrome (SjS) has not changed substantially in recent decades: treatment decisions remain challenging in clinical practice, without a specific therapeutic target beyond the relief of symptoms as the most important goal. In view of this scenario, the European League Against Rheumatism (EULAR) promoted and supported an international collaborative study (EULAR SS Task Force) aimed at developing the first EULAR evidence and consensus-based recommendations for the management of patients with SjS with topical and systemic medications. The aim was to develop a rational therapeutic approach to SjS patients useful for healthcare professionals, physicians undergoing specialist training, medical students, the pharmaceutical industry and drug regulatory organisations following the 2014 EULAR standardised operating procedures. The Task Force (TF) included specialists in rheumatology, internal medicine, oral health, ophthalmology, gynaecology, dermatology and epidemiology, statisticians, general practitioners, nurses and patient representatives from 30 countries of the 5 continents. Evidence was collected from studies including primary SjS patients fulfilling the 2002/2016 criteria; when no evidence was available, evidence from studies including associated SjS or patients fulfilling previous sets of criteria was considered and extrapolated. The TF endorsed the presentation of general principles for the management of patients with SjS as three overarching, general consensus-based recommendations and 12 specific recommendations that form a logical sequence, starting with the management of the central triplet of symptoms (dryness, fatigue and pain) followed by the management of systemic disease. The recommendations address the use of topical oral (saliva substitutes) and ocular (artificial tear drops, topical non-steroidal anti-inflammatory drugs, topical corticosteroids, topical CyA, serum tear drops) therapies, oral muscarinic agonists (pilocarpine, cevimeline), hydroxychloroquine, oral glucocorticoids, synthetic immunosuppressive agents (cyclophosphamide, azathioprine, methotrexate, leflunomide and mycophenolate), and biological therapies (rituximab, abatacept and belimumab). For each recommendation, levels of evidence (mostly modest) and TF agreement (mostly very high) are provided. The 2019 EULAR recommendations are based on the evidence collected in the last 16 years in the management of primary 2002 SjS patients and on discussions between a large and broadly international TF. The recommendations synthesise current thinking on SjS treatment in a set of overarching principles and recommendations. We hope that the current recommendations will be broadly applied in clinical practice and/or serve as a template for national societies to develop local recommendations.

Sinomenine facilitates the efficacy of gabapentin or ligustrazine hydrochloride in animal models of neuropathic pain

Management of chronic pain is restricted by the lack of effective tools. This study evaluated the efficacies of sinomenine combined gabapentin or ligustrazine hydrochloride in treating peripheral and central chronic neuropathic pain. The study was conducted in mice with photochemically induced sciatic nerve injury, and in rats with photochemically induced spinal cord injury. For assessing the effectiveness of combined therapy, sinomenine, gabapentin or ligustrazine hydrochloride was injected intraperitoneally (i.p.), and pain behavioral tests were performed. At sub-effective dosages, pre-administration of sinomenine (for 60 min) plus gabapentin or ligustrazine hydrochloride, generated significant anti-allodynic effects in mice or rats with peripheral or central neuropathic pain. However, these effects were abolished when gabapentin or ligustrazine hydrochloride was pre-administered, and then sinomenine was given 60 min later. The combined efficacies of sinomenine and gabapentin or ligustrazine hydrochloride, cannot be blocked or reversed by the naloxone, suggesting the underlying mechanism is not mediated by opioid receptors. Moreover, following repeated treatments, sinomenine and gabapentin combination increased the baseline mechanical threshold, while generating prolonged analgesia, without introducing notable side effects. Sinomenine can enhance the efficacy of gabapentin or ligustrazine hydrochloride in rodent models of peripheral or central neuropathic pain, without introducing tolerance or other notable side effects. Findings of current study suggest that combing sinomenine and gabapentin or ligustrazine hydrochloride could be highly beneficial in neuropathic pain therapies.

Withdrawing attempt and its related factors among Iranian substance users: a case-control study

Background

Substance dependence is considered as an important health disorder with a wide and serious range of psychosocial effects. With regard to the large number of people with substance dependency in Iran and high failure rate of quitting attempts, the aim of this study was to identify contributing factors to quitting substance dependency among patients in Yasuj the capital of Kohgilooyeh and Boyerahmad province.

Methods

This case-control study was conducted on 150 current substance users (as control group) and 187 patients who voluntarily introduced themselves to governmental and private residential treatment camps (as case group). The participants in the case group were selected via two stage cluster sampling among those admitted to residential treatment camps. Those in the control group were selected via snowball sampling among current substance users.

Results

Based on the results from multiple logistic regression analysis, significant associations were observed between attempting to withdraw substance use and father’s education (OR _{high school or university /illiterate} = 0.36, 95%CI: 0.18 to 0.72, P = 0.004) and smoking (OR _yes/no = 4.26, 95%CI = 1.90 to 9.57, P < 0.001) were identified.

Conclusions

This study introduced father’s education as an obstacle to attempting to quit substance dependency. This finding can be justified by easier access to money and therefore less financial pressure in providing drugs among those with wealthier families. Also, smoking was more common among those who registered with the camps. This is possibly due to the quitters attempt to replace the drugs with cigar smoking as an alternative. Training families in helping their members in preventing or quitting substance dependency is a potentially useful approach. Studies are needed to define whether the common belief that smoking helps in withdrawing substance use is helpful.

Risk factors of opioid-induced adverse reactions in elderly male outpatients of Korea Veterans Hospital

Background

Risk factors associated with opioid-induced adverse reactions (OIARs) in the elderly population have not been well defined. The objective of this study was to determine effects of various risk factors on incidence of OIARs in male elderly patients.

Methods

A retrospective cohort study in Korea Veterans Hospital was performed. Data were analyzed in male patients aged 65 years and older who received morphine, oxycodone, or codeine. Binomial variables describing patient-related and drug-related characteristics were constructed. Associations between these variables and frequency of OIARs were determined. Odds ratio (OR) and adjusted odds ratio (AOR) were calculated from univariate and multivariable analyses, respectively. Attributable risk was obtained by (1–1/OR)*100%.

Results

Of 316 patients, 28% experienced at least one adverse event. The most common adverse events were gastrointestinal problems (n = 59) and central nerve system adverse effects (n = 20). The odds of OIARs in patients with opioid use ≥12 weeks was increased by 80% compared to those with opioid use < 12 weeks. Attributable risk of GABA analogues was 64~78% in constructed Models. Compared to codeine users, patients using morphine and oxycodone had 653 and 473% increased odds for OIARs, respectively. MME ≥ 60 mg/day had a 317% increased odds for OIARs (95% CI: 1.92–9.04) compared to MME < 60 mg/day. Opioid combination therapy had a 139% increased odds for OIARs compared to monotherapy.

Conclusions

These findings have significant implications for clinical use of opioid in elderly patients. Our study suggests that low dose short-term use will pose less risk of OIARs for the elderly, whereas concomitant use of GABA analogues, strong opioids and dual-opioid therapy may increase the risk of OIARs. Therefore, clinician should carefully monitor patients when starting opioid therapy in older population.

The Adjective Rating Scale for Withdrawal: Validation of its ability to assess severity of prescription opioid misuse

BACKGROUND

Withdrawal symptoms have been widely shown to be a useful indicator of the severity of opioid dependence. One of the most used instruments to assess them is the Adjective Rating Scale for Withdrawal (ARSW). However, there is a lack of adaptations and validations for its use with prescription opioids, even less for chronic pain patients under treatment with these analgesics. Thus, the aims of this study were to analyse the psychometric properties and invariance across gender of the ARSW in a sample of chronic noncancer pain patients.

METHODS

Data were collected from 208 consumers of opioid medication, chronic noncancer pain patients. Participants completed sociodemographic, ARSW, prescription opioid dependence (DSM-IV-TR) and prescription opioid-use disorder (DSM-5) measurements. Gender invariance was assessed through multigroup confirmatory factor analysis (CFA).

RESULTS

The ARSW showed a unidimensional factor structure and high internal consistency (Cronbach's alpha = 0.85). Multigroup CFA showed configural, metric, scalar and strict invariances of ARSW across gender. Predictive validity analyses indicated that ARSW has good capacity for identifying the severity of prescription opioid-use disorder, using both DSM-IV-TR and DSM-5 criteria.

CONCLUSIONS

These findings show that the ARSW is a valid and reliable tool for use in the assessment of the withdrawal of prescription opioids in chronic pain patients under treatment with these analgesics, regardless of their gender.

SIGNIFICANCE

Findings supported the reliability and validity of the ARSW to assess withdrawal of prescription opioids in individuals with chronic noncancer pain. The instrument can be applied indistinctly in men and women. An increase in the ARSW scores could be used as an indicator of potential risk of prescription opioid-use disorder during long-term treatments.

Nicotinic modulation of descending pain control circuitry

Along with the well-known rewarding effects, activation of nicotinic acetylcholine receptors (nAChRs) can also relieve pain, and some nicotinic agonists have analgesic efficacy similar to opioids. A major target of analgesic drugs is the descending pain modulatory pathway, including the ventrolateral periaqueductal gray (vlPAG) and the rostral ventromedial medulla (RVM). Although activating nAChRs within this circuitry can be analgesic, little is known about the subunit composition and cellular effects of these receptors, particularly within the vlPAG. Using electrophysiology in brain slices from adult male rats, we examined nAChR effects on vlPAG neurons that project to the RVM. We found that 63% of PAG-RVM projection neurons expressed functional nAChRs, which were exclusively of the α7-subtype. Interestingly, the neurons that express α7 nAChRs were largely nonoverlapping with those expressing μ-opioid receptors (MOR). As nAChRs are excitatory and MORs are inhibitory, these data suggest distinct roles for these neuronal classes in pain modulation. Along with direct excitation, we also found that presynaptic nAChRs enhanced GABAergic release preferentially onto neurons that lacked α7 nAChRs. In addition, presynaptic nAChRs enhanced glutamatergic inputs onto all PAG-RVM projection neuron classes to a similar extent. In behavioral testing, both systemic and intra-vlPAG administration of the α7 nAChR-selective agonist, PHA-543,613, was antinociceptive in the formalin assay. Furthermore, intra-vlPAG α7 antagonist pretreatment blocked PHA-543,613-induced antinociception via either administration method. Systemic administration of submaximal doses of the α7 agonist and morphine produced additive antinociceptive effects. Together, our findings indicate that the vlPAG is a key site of action for α7 nAChR-mediated antinociception.

Work Enabling Opioid Management

OBJECTIVE

This study describes the relationship between opioid prescribing and ability to work.

METHODS

The opioid prescription patterns of 4994 claimants were studied. Three groups were constructed: 1) at least 3 consecutive months prescribed (chronic opioid therapy; COT); 2) less than 3 consecutive months prescribed (acute opioid therapy; AOT); and 3) no opioids prescribed. Variables included sex, age, daily morphine equivalent dose (MED), days opioids were prescribed, temporary total days (TTDs), and medical/indemnity/total costs.

RESULTS

The COT versus AOT claimants had higher opioid costs ($8618 vs $94), longer TTD (636.2 vs 182.3), and average MED (66.8 vs 34.9). Only 2% of the COT cohort were not released to work. Fifty-seven percent of patients in the COT category (64 of 112) were released to work while still receiving opioids.

CONCLUSION

COT does not preclude ability to work when prescribing within established guidelines.

Functional Magnetic Resonance Imaging Evaluation of Auricular Percutaneous Electrical Neural Field Stimulation for Fibromyalgia: Protocol for a Feasibility Study

Background

Fibromyalgia is a chronic pain state that includes widespread musculoskeletal pain, fatigue, psychiatric symptoms, cognitive and sleep disturbances, and multiple somatic symptoms. Current therapies are often insufficient or come with significant risks, and while there is an increasing demand for non-pharmacologic and especially non-opioid pain management such as that offered through complementary and alternative medicine therapies, there is currently insufficient evidence to recommend these therapies. Percutaneous electrical neural stimulation (PENS) is an evidence-based treatment option for pain conditions that involves electrical current stimulation through needles inserted into the skin. Percutaneous electrical neural field stimulation (PENFS) of the auricle is similar to PENS, but instead of targeting a single neurovascular bundle, PENFS stimulates the entire ear, covering all auricular branches of the cranial nerves, including the vagus nerve. The neural mechanisms of PENFS for fibromyalgia symptom relief are unknown.

Objective

We hypothesize that PENFS treatment will decrease functional brain connectivity between the default mode network (DMN) and right posterior insula in fibromyalgia patients. We expect that the decrease in functional connectivity between the DMN and insula will correlate with patient-reported analgesic improvements as indicated by the Defense and Veterans Pain Rating Scale (DVPRS) and will be anti-correlated with patient-reported analgesic medication consumption. Exploratory analyses will be performed for further hypothesis generation.

Methods

A total of 20 adults from the Atlanta Veterans Affairs Medical Center diagnosed with fibromyalgia will be randomized into 2 groups: 10 subjects to a control (standard therapy) group and 10 subjects to a PENFS treatment group. The pragmatic, standard therapy group will include pharmacologic treatments such as anticonvulsants, non-steroidal anti-inflammatory drugs, topical agents and physical therapy individualized to patient comorbidities and preferences, prescribed by a pain management practitioner. The PENFS group will include the above therapies in addition to the PENFS treatments. The PENFS subject group will have the Neuro-Stim System placed on the ear for 5 days then removed and replaced once per week for 4 weeks. The primary outcome will be resting functional magnetic resonance imaging connectivity between DMN and insula, which will also be correlated with pain relief and functional improvements. This connectivity will be analyzed utilizing functional connectivity magnetic resonance imaging (fcMRI) and will be compared with patient-reported analgesic improvements as indicated by the DVPRS and patient-reported analgesic medication consumption. Pain and function will be further evaluated using Patient-Reported Outcomes Measurement Information System measures and measures describing a person’s functional status from Activity and Participation section of the International Classification of Functioning Disability and Health.

Results

This trial has been funded by the Veterans Health Administration Program Office. This study attained approval by the Emory University/Veterans Affairs (VA) institutional review board and VA Research & Development committee. Institutional review board expedited approval was granted on 2/7/17 (IRB00092224). The study start date is 6/1/17 and estimated completion date is 5/31/20. The recruitment started in June 2017.

Conclusions

This is a feasibility study that is meant to demonstrate the practicality of using fcMRI to study the neural correlates of PENFS outcomes and provide information regarding power calculations in order to design and execute a larger randomized controlled clinical trial to determine the efficacy of PENFS for improving pain and function.

Trial Registration

ClinicalTrials.gov NCT03008837; https://clinicaltrials.gov/ct2/show/NCT03008837 (Archived by WebCite at http://www.webcitation.org/6wrY3NmaQ).

Misuse of Opioids in Orthopaedic Postoperative Patients

OBJECTIVE

In light of the recent uptrend in the prescription of opioids, this study seeks to identify patterns of opioid misuse among orthopaedic postoperative patients and principal external sources in obtaining these medications.

DESIGN

Ten-month survey-based study.

SETTING

Two Level I trauma centers (urban and suburban).

PATIENTS/PARTICIPANTS

Two hundred seven patients between the ages of 18 and 89 years who underwent surgical fixation of fractures involving the pelvis, long bones, or periarticular regions of the knee, ankle, elbow, and wrist.

MAIN OUTCOME MEASUREMENTS

Patients who believed they were undermedicated, used prescribed opioids at higher than recommended doses, and took extra opioids in addition to their prescribed analgesics were analyzed by age, employment, income, education, controlled substance use, pain interference with activities of daily living, and anatomic surgical site.

RESULTS

One hundred eighty-two patients completed the survey; 19.2% of patients (n = 35) felt undermedicated [unemployed (P < 0.05), low income (P < 0.05), and self-reported controlled substance users (P < 0.05)]; 12.6% of patients (n = 23) admitted to using pain medications at a higher dose than prescribed [unemployed (P < 0.05), lower income (P < 0.05), nonhigh school graduates (P < 0.05), and previous controlled substance users (P < 0.05)]; 9.3% (n = 17) admitted to using external opioids [unemployed patients (P < 0.05) and self-reported controlled substance users (P < 0.05)]. Major sources of extraneous opioids include family/friends (n = 5) and other doctors (n = 4).

CONCLUSION

Unemployed and lower-income patients were significantly more likely to believe that their surgeon was not prescribing them enough pain medications as well as use their prescribed opioid medications at a higher than recommended dose compared with their employed counterparts with higher incomes. Unemployed patients were also significantly more likely to use additional opioid analgesics in addition to those prescribed to them by their primary surgeon. Surgeon awareness of a patient's socioeconomic background and associated risk of opioid misuse is crucial to prescribe the safest most effective pain regimen.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Anti-nerve growth factor therapy increases spontaneous day/night activity in mice with orthopedic surgery-induced pain

Total knee arthroplasty (TKA) and total hip arthroplasty (THA) are 2 of the most common and successful surgical interventions to relieve osteoarthritis pain. Control of postoperative pain is critical for patients to fully participate in the required physical therapy which is the most influential factor in effective postoperative knee rehabilitation. Currently, opiates are a mainstay for managing postoperative orthopedic surgery pain including TKA or THA pain. Recently, issues including efficacy, dependence, overdose, and death from opiates have made clinicians and researchers more critical of use of opioids for treating nonmalignant skeletal pain. In the present report, a nonopiate therapy using a monoclonal antibody raised against nerve growth factor (anti-NGF) was assessed for its ability to increase the spontaneous activity of the operated knee joint in a mouse model of orthopedic surgery pain-induced by drilling and coring the trochlear groove of the mouse femur. Horizontal activity and velocity and vertical rearing were continually assessed over a 20 hours day/night period using automated activity boxes in an effort to reduce observer bias and capture night activity when the mice are most active. At days 1 and 3, after orthopedic surgery, there was a marked reduction in spontaneous activity and vertical rearing; anti-NGF significantly attenuated this decline. The present data suggest that anti-NGF improves limb use in a rodent model of joint/orthopedic surgery and as such anti-NGF may be useful in controlling pain after orthopedic surgeries such as TKA or THA.

Estimating the health care burden of prescription opioid abuse in five European countries

Background

Opioid abuse, including abuse of prescription opioids (“RxOs”) and illicit substances like heroin, is a serious public health issue in Europe. Currently, there is limited data on the magnitude of RxO abuse in Europe, despite increasing public and scientific interest in the issue. The purpose of this study was to use the best-available data to derive comparable estimates of the health care burden of RxO abuse in France, Germany, Italy, Spain, and the United Kingdom (EU5).

Methods

Published data on the prevalence of problem opioid use and the share of opioid abuse patients reporting misuse of non-heroin opioids were used to estimate the prevalence of RxO abuse in the EU5 countries. The costs of RxO abuse were calculated by applying published estimates of the incremental health care costs of opioid abuse to country-specific estimates of the costs of chronic pain conditions. These estimates were input into an economic model that quantified the health care burden of RxO abuse in each of the EU5 countries. Sensitivity analyses examined key assumptions.

Results

Based on best-available current data, prevalence estimates of RxO abuse ranged from 0.7 to 13.7 per 10,000 individuals across the EU5 countries. Estimates of the incremental health care costs of RxO abuse ranged from €900 to €2,551 per patient per year. The annual health care cost burden of RxO abuse ranged from €6,264 to €279,927 per 100,000 individuals across the EU5 countries.

Conclusion

This study suggests that RxO abuse imposes a cost burden on health systems in the five largest European countries. The extent of RxO abuse in Europe should be monitored given the potential for change over time. Continued efforts should be made to collect reliable data on the prevalence and costs of RxO abuse in Europe to facilitate an accurate characterization of the extent of this potentially growing problem.

Opioid Analgesics

Chronic pain is an international health issue of immense importance that is influenced by both physical and psychological factors. Opioids are useful in treating chronic pain but have accompanying complications. It is important for clinicians to understand the basics of opioid pharmacology, the benefits and adverse effects of opioids, and related problematic issues of tolerance, dependence, and opioid-induced hyperalgesia. In this article, the role of psychiatric comorbidity and the use of validated assessment tools to identify individuals who are at the greatest risk for opioid misuse are discussed. Additionally, interventional treatment strategies for patients with chronic pain who are at risk for opioid misuse are presented. Specific behavioral interventions designed to improve adherence with prescription opioids among persons treated for chronic pain, such as frequent monitoring, periodic urine screens, opioid therapy agreements, opioid checklists, and motivational counseling, are also reviewed. Use of state-sponsored prescription drug monitoring programs is also encouraged. Areas requiring additional investigation are identified, and the future role of abuse-deterrent opioids and innovative technology in addressing issues of opioid therapy and pain are presented.

Opioids for low back pain

Back pain affects most adults, causes disability for some, and is a common reason for seeking healthcare. In the United States, opioid prescription for low back pain has increased, and opioids are now the most commonly prescribed drug class. More than half of regular opioid users report back pain. Rates of opioid prescribing in the US and Canada are two to three times higher than in most European countries. The analgesic efficacy of opioids for acute back pain is inferred from evidence in other acute pain conditions. Opioids do not seem to expedite return to work in injured workers or improve functional outcomes of acute back pain in primary care. For chronic back pain, systematic reviews find scant evidence of efficacy. Randomized controlled trials have high dropout rates, brief duration (four months or less), and highly selected patients. Opioids seem to have short term analgesic efficacy for chronic back pain, but benefits for function are less clear. The magnitude of pain relief across chronic non-cancer pain conditions is about 30%. Given the brevity of randomized controlled trials, the long term effectiveness and safety of opioids are unknown. Loss of long term efficacy could result from drug tolerance and emergence of hyperalgesia. Complications of opioid use include addiction and overdose related mortality, which have risen in parallel with prescription rates. Common short term side effects are constipation, nausea, sedation, and increased risk of falls and fractures. Longer term side effects may include depression and sexual dysfunction. Screening for high risk patients, treatment agreements, and urine testing have not reduced overall rates of opioid prescribing, misuse, or overdose. Newer strategies for reducing risks include more selective prescription of opioids and lower doses; use of prescription monitoring programs; avoidance of co-prescription with sedative hypnotics; and reformulations that make drugs more difficult to snort, smoke, or inject.

Plasticity of α2-adrenergic spinal antinociception following nerve injury: selective, bidirectional interaction with the delta opioid receptor

Interactions of opioid receptors with other receptor families can be made use of to improve analgesia and reduce adverse effects of opioid analgesics. We investigated interactions of the α2-adrenergic receptor (α2AR) with opioid receptors of the mu (MOR) and delta (DOR) types in the spinal dorsal horn in an animal model of neuropathic pain induced by spinal nerve ligation. Nine days after nerve injury, immunoreactivity for the α2AR subtype A (α2AAR) was increased both in tissue homogenates and at pre- and post-synaptic sites in transverse sections. The efficacy of spinally administered α2AAR agonist guanfacine at reducing C-fiber-evoked field potentials was increased in nerve-ligated rats. This reducing effect was impaired by simultaneous administration of DOR antagonist naltrindole, but not MOR antagonist CTOP, suggesting that concurrent DOR activation was required for α2AAR-mediated inhibition. While DOR agonist deltorphin II and MOR agonist DAMGO both effectively depressed C-fiber-evoked spinal field potentials, DOR- but not MOR-mediated depression was enhanced by subclinical guanfacine. In conscious, nerve-ligated rats, chronically administered deltorphin II produced stable thermal and mechanical antinociception over the 9 following days after nerve injury without apparent signs of habituation. Such an effect was dramatically enhanced by co-administration of a low dose of guanfacine, which reversed thermal and mechanical thresholds to levels near those prior to injury. The results suggest that spinal, α2AAR-mediated antinociception is increased after nerve injury and based on DOR co-activation. We demonstrate in vivo that α2AAR/DOR interaction can be exploited to provide effective behavioral antinociception during neuropathic pain.

A pain research agenda for the 21st century

Chronic pain represents an immense clinical problem. With tens of millions of people in the United States alone suffering from the burden of debilitating chronic pain, there is a moral obligation to reduce this burden by improving the understanding of pain and treatment mechanisms, developing new therapies, optimizing and testing existing therapies, and improving access to evidence-based pain care. Here, we present a goal-oriented research agenda describing the American Pain Society's vision for pain research aimed at tackling the most pressing issues in the field.

PERSPECTIVE

This article presents the American Pain Society's view of some of the most important research questions that need to be addressed to advance pain science and to improve care of patients with chronic pain.

Repeated sinomenine administration alleviates chronic neuropathic pain-like behaviours in rodents without producing tolerance

Background and aims We have previously reported that systemic administration of sinomenine produced antinociception in various experimental pain conditions in rodents, particularly in models of neuropathic pain. In the present study we assessed the effects of repeated administration of sinomenine in two rodent models of neuropathic pain in order to study the development of tolerance. Methods The analgesic effect of sinomenine was tested in female Sprague-Dawley rats that exhibited mechanical and cold hypersensitivity following ischaemic injury to the spinal cord and in male C57/BL6 mice that developed mechanical hypersensitivity after ischaemic injury to the sciatic nerve. Briefly, the animals were anaesthetized and injected i.v. with the photosensitizing dye erythrosine B. Vertebral segments T12 to T13 in rats or the sciatic nerve in mice were exposed and irradiated under an argon ion laser for 10min or 45s, respectively. In rats, mechanical hypersensitivity to pressure with von Frey hairs, the response to brushing and decreasing cold temperature were tested in the flanks or upper back areas. In mice, mechanical hypersensitivity on the hind paw to von Frey hairs and response to cold following a drop of acetone were measured. Sinomenine was administered i.p. in rats and p.o. in mice at 10:00 and 16:00, twice a day for 5 days. Response threshold before and 2h after drug administration at 10.00h was recorded. Results Repeated administration of sinomenine at 10 or 20mg/kg twice a day, doses that have no analgesic effect as single injection, alleviated mechanical, but not cold allodynia in spinally injured rats and the effect was maintained during the 5 day treatment period with no signs of tolerance. Furthermore, the pre-drug response threshold was significantly elevated during repeated treatment with 20mg/kg sinomenine. Sinomenine administered at 40mg/kg twice a day for 5 days significantly reduced mechanical and cold alldoynia, elevated pre-drug response threshold without tolerance development in spinally injured rats. Similarly, sinomenine at 80mg/kg twice a day for 5 days significantly reduced mechanical allodynia in mice with sciatic nerve injury and increased pre-drug response threshold with no sign of tolerance. The effect of sinomenine on response threshold persisted for days after termination of the 5 day drug administration. Conclusions The results suggest that repeated administration of simomenine produced an enhanced anti-allodynic effect without tolerance in rodent models of neuropathic pain. Implications Sinomenine may be tested as a novel analgesic in treating some forms of chronic neuropathic pain in patients.

Costs and Consequences: A Review of Discharge Opioid Prescribing for ongoing Management of Acute Pain

Over recent years there has been a growing need for patients to be sent home from hospital with prescribed opioids for ongoing management of their acute pain. Increasingly complex surgery is being performed on a day-stay or 23-hour-stay basis and inpatients after major surgery and trauma are now discharged at a much earlier stage than in the past. However, prescription of opioids to be self-administered at home is not without risk. In addition to the potential for acute adverse effects, including opioid-induced ventilatory impairment and impairment of driving skills, a review of the literature shows that opioid use continues in some patients for some years after surgery. There are also indications that over-prescription of discharge opioids occur with a significant amount not consumed, resulting in a potentially large pool of unused opioid available for later use by either the patient or others in the community. Concerns about the potential for harm arising from prescription of opioids for ongoing acute pain management after discharge are relatively recent. However, at a time when serious problems resulting from the non-medical use of opioids have reached epidemic proportions in the community, all doctors must be aware of the potential risks and be able to identify and appropriately manage patients where there might be a risk of prolonged opioid use or misuse. Anaesthetists are ideally placed to exercise stewardship over the use of opioids, so that these drugs can maintain their rightful place in the post-discharge analgesic pharmacopoeia.