High-dose opioids for chronic non-cancer pain: an overview of Cochrane Reviews

Data-Driven Identification of Potentially Successful Intervention Implementations Using 5 Years of Opioid Prescribing Data: Retrospective Database Study

BACKGROUND

We have previously demonstrated that opioid prescribing increased by 127% between 1998 and 2016. New policies aimed at tackling this increasing trend have been recommended by public health bodies, and there is some evidence that progress is being made.

OBJECTIVE

We sought to extend our previous work and develop a data-driven approach to identify general practices and clinical commissioning groups (CCGs) whose prescribing data suggest that interventions to reduce the prescribing of opioids may have been successfully implemented.

METHODS

We analyzed 5 years of prescribing data (December 2014 to November 2019) for 3 opioid prescribing measures-total opioid prescribing as oral morphine equivalent per 1000 registered population, the number of high-dose opioids prescribed per 1000 registered population, and the number of high-dose opioids as a percentage of total opioids prescribed. Using a data-driven approach, we applied a modified version of our change detection Python library to identify reductions in these measures over time, which may be consistent with the successful implementation of an intervention to reduce opioid prescribing. This analysis was carried out for general practices and CCGs, and organizations were ranked according to the change in prescribing rate.

RESULTS

We identified a reduction in total opioid prescribing in 94 (49.2%) out of 191 CCGs, with a median reduction of 15.1 (IQR 11.8-18.7; range 9.0-32.8) in total oral morphine equivalence per 1000 patients. We present data for the 3 CCGs and practices demonstrating the biggest reduction in opioid prescribing for each of the 3 opioid prescribing measures. We observed a 40% proportional drop (8.9% absolute reduction) in the regular prescribing of high-dose opioids (measured as a percentage of regular opioids) in the highest-ranked CCG (North Tyneside); a 99% drop in this same measure was found in several practices (44%-95% absolute reduction). Decile plots demonstrate that CCGs exhibiting large reductions in opioid prescribing do so via slow and gradual reductions over a long period of time (typically over a period of 2 years); in contrast, practices exhibiting large reductions do so rapidly over a much shorter period of time.

CONCLUSIONS

By applying 1 of our existing analysis tools to a national data set, we were able to identify rapid and maintained changes in opioid prescribing within practices and CCGs and rank organizations by the magnitude of reduction. Highly ranked organizations are candidates for further qualitative research into intervention design and implementation.

Peripheral Neuroinflammation and Pain: How Acute Pain Becomes Chronic

The number of individuals suffering from severe chronic pain and its social and financial impact is staggering. Without significant advances in our understanding of how acute pain becomes chronic, effective treatments will remain out of reach. This mini review will briefly summarize how critical signaling pathways initiated during the early phases of peripheral nervous system inflammation/ neuroinflammation establish long-term modifications of sensory neuronal function. Together with the recruitment of non-neuronal cellular elements, nociceptive transduction is transformed into a pathophysiologic state sustaining chronic peripheral sensitization and pain. Inflammatory mediators, such as nerve growth factor (NGF), can lower activation thresholds of sensory neurons through posttranslational modification of the pain-transducing ion channels transient-receptor potential TRPV1 and TRPA1. Performing a dual role, NGF also drives increased expression of TRPV1 in sensory neurons through the recruitment of transcription factor Sp4. More broadly, Sp4 appears to modulate a nociceptive transcriptome including TRPA1 and other genes encoding components of pain transduction. Together, these findings suggest a model where acute pain evoked by peripheral injury-induced inflammation becomes persistent through repeated cycles of TRP channel modification, Sp4-dependent overexpression of TRP channels and ongoing production of inflammatory mediators.

Oxycodone: A Current Perspective on Its Pharmacology, Abuse, and Pharmacotherapeutic Developments

Oxycodone, a semisynthetic derivative of naturally occurring thebaine, an opioid alkaloid, has been available for more than 100 years. Although thebaine cannot be used therapeutically due to the occurrence of convulsions at higher doses, it has been converted to a number of other widely used compounds that include naloxone, naltrexone, buprenorphine, and oxycodone. Despite the early identification of oxycodone, it was not until the 1990s that clinical studies began to explore its analgesic efficacy. These studies were followed by the pursuit of several preclinical studies to examine the analgesic effects and abuse liability of oxycodone in laboratory animals and the subjective effects in human volunteers. For a number of years oxycodone was at the forefront of the opioid crisis, playing a significant role in contributing to opioid misuse and abuse, with suggestions that it led to transitioning to other opioids. Several concerns were expressed as early as the 1940s that oxycodone had significant abuse potential similar to heroin and morphine. Both animal and human abuse liability studies have confirmed, and in some cases amplified, these early warnings. Despite sharing a similar structure with morphine and pharmacological actions also mediated by the μ-opioid receptor, there are several differences in the pharmacology and neurobiology of oxycodone. The data that have emerged from the many efforts to analyze the pharmacological and molecular mechanism of oxycodone have generated considerable insight into its many actions, reviewed here, which, in turn, have provided new information on opioid receptor pharmacology. SIGNIFICANCE STATEMENT: Oxycodone, a μ-opioid receptor agonist, was synthesized in 1916 and introduced into clinical use in Germany in 1917. It has been studied extensively as a therapeutic analgesic for acute and chronic neuropathic pain as an alternative to morphine. Oxycodone emerged as a drug with widespread abuse. This article brings together an integrated, detailed review of the pharmacology of oxycodone, preclinical and clinical studies of pain and abuse, and recent advances to identify potential opioid analgesics without abuse liability.

High-dose opioids for chronic non-cancer pain: an overview of Cochrane Reviews

BACKGROUND

This overview was originally published in 2017, and is being updated in 2022.  Chronic pain is typically described as pain on most days for at least three months. Chronic non-cancer pain (CNCP) is any chronic pain that is not due to a malignancy. Chronic non-cancer pain in adults is a common and complex clinical issue, for which opioids are prescribed by some physicians for pain management. There are concerns that the use of high doses of opioids for CNCP lacks evidence of effectiveness, and may increase the risk of adverse events.

OBJECTIVES

To describe the evidence from Cochrane Reviews and overviews regarding the efficacy and safety of high-dose opioids (defined as 200 mg morphine equivalent or more per day) for CNCP.

METHODS

We identified Cochrane Reviews and overviews by searching the Cochrane Database of Systematic Reviews in The Cochrane Library. The date of the last search was 21 July 2022. Two overview authors independently assessed the search results. We planned to analyse data on any opioid agent used at a high dose for two weeks or more for the treatment of CNCP in adults.

MAIN RESULTS

We did not identify any reviews or overviews that met the inclusion criteria. The excluded reviews largely reflected low doses or titrated doses, where all doses were analysed as a single group; we were unable to extract any data for high-dose use only.

AUTHORS' CONCLUSIONS

There is a critical lack of high-quality evidence, in the form of Cochrane Reviews, about how well high-dose opioids work for the management of CNCP in adults, and regarding the presence and severity of adverse events.  No evidence-based argument can be made on the use of high-dose opioids, i.e. 200 mg morphine equivalent or more daily, in clinical practice. Considering that high-dose opioids have been, and are still being used in clinical practice to treat CNCP, knowing about the efficacy and safety of these higher doses is imperative.

Long-term, high-dose opioid prescription for chronic non-cancer pain in primary care: an observational study

BACKGROUND

Opioid prescriptions for chronic pain have risen sharply over the last 25 years; harms associated with these drugs are related to dose and length of use.

AIM

The main aim of this study was to identify patients prescribed long-term, high-dose (LTHD) opioids in the community and to assess the prevalence of such use.

DESIGN & SETTING

An observational study of opioid prescribing in two demographically dissimilar GP practices in North Wales, UK.

METHOD

Details of opioid prescriptions were collected for 22 841 patients, of whom 1488 (6.5%) were being prescribed opioids on the census date. Exhaustive examination of the data identified all patients who were prescribed oral morphine equivalent doses of ≥120 mg/day for ≥1 year.

RESULTS

All these patients were being prescribed ≥120 mg/day, as a single drug, morphine, oxycodone, fentanyl, or buprenorphine, irrespective of opioid polypharmacy. Across both practices, 1.71/1000 patients were identified as LTHD users of opioid medication for chronic non-cancer pain (CNCP). Prevalence was similar in the two practices. Repetition of the process until January 2021 showed no change in the pattern.

CONCLUSION

This study offers confirmation that a significant group of patients are prescribed long-term opioid medication for chronic pain at doses that are unlikely to be effective in reducing pain, but are likely to have harmful consequences. The findings offer a simple, reliable, and practical method of data extraction to identify these patients individually from routinely collected prescribing data, which will help in monitoring and treating individuals and establishing the problem prevalence.

Diagnostic and Predictive Capacity of the Spanish Versions of the Opioid Risk Tool and the Screener and Opioid Assessment for Patients with Pain-Revised: A Preliminary Investigation in a Sample of People with Noncancer Chronic Pain

INTRODUCTION

Accurate assessment of the risk of opioid abuse and misuse in people with noncancer chronic pain is crucial for their prevention. This study aimed to provide preliminary evidence of the diagnostic and predictive capacity of the Spanish versions of the Opioid Risk Tool (ORT) and the Screener and Opioid Assessment for Patients with Pain-Revised (SOAPP-R).

METHODS

We used the Current Opioid Misuse Measure (COMM) as criterion measure to assess the capacity of each tool to identify patients misusing opioids at the time of the assessment. Eighteen months later, we used the COMM and the Drug Abuse Screening Test-10 (DAST-10) to assess their predictive capacity. In total, 147 people with noncancer chronic pain participated in the diagnostic study, and 42 in the predictive study.

RESULTS

Receiver operating curve analysis showed that the SOAPP-R had an excellent capacity to identify participants who were misusing opioids at the time of assessment (area under the curve [AUC] = 0.827). The diagnostic capacity of the ORT was close to acceptable (AUC = 0.649-0.669), whereas its predictive capacity was poor (AUC = 0.522-0.554). The predictive capacity of the SOAPP-R was close to acceptable regarding misuse (AUC = 0.672) and poor regarding abuse (AUC = 0.423).

CONCLUSION

In the setting of Spanish-speaking communities, clinicians should be cautious when using these instruments to make decisions on opioid administration. Further research is needed on the diagnostic and predictive capacity of the Spanish versions of both instruments.

Trends in the Prescription of Strong Opioids for Chronic Non-Cancer Pain in Primary Care in Catalonia: Opicat-Padris-Project

In chronic non-cancer pain (CNCP), evidence of the effectiveness of strong opioids (SO) is very limited. Despite this, their use is increasingly common. To examine SO prescriptions, we designed a descriptive, longitudinal, retrospective population-based study, including patients aged ≥15 years prescribed SO for ≥3 months continuously in 2013–2017 for CNCP in primary care in Catalonia. Of the 22,691 patients included, 17,509 (77.2%) were women, 10,585 (46.6%) were aged >80 years, and most had incomes of <€18,000 per year. The most common diagnoses were musculoskeletal diseases and psychiatric disorders. There was a predominance of transdermal fentanyl in the defined daily dose (DDD) per thousand inhabitants/day, with the greatest increase for tapentadol (312% increase). There was an increase of 66.89% in total DDD per thousand inhabitants/day for SO between 2013 (0.737) and 2017 (1.230). The mean daily oral morphine equivalent dose/day dispensed for all drugs was 83.09 mg. Transdermal fentanyl and immediate transmucosal release were the largest cost components. In conclusion, there was a sustained increase in the prescription of SO for CNCP, at high doses, and in mainly elderly patients, predominantly low-income women. The new SO are displacing other drugs.

OUP accepted manuscript

Objective

To review evidence from longitudinal studies on the association between prescription opioid use and common mood and anxiety symptoms.

Design

We conducted a systematic review and meta-analysis according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Methods

We searched PubMed, Embase, and PsycINFO for search terms related to opioids AND (depression OR bipolar OR anxiety OR post-traumatic stress disorder [PTSD]). Findings were summarized narratively, and random-effects meta-analyses were used to pool effect sizes.

Results

We identified 10,290 records and found 10 articles that met our inclusion criteria. Incidence studies showed that people who used prescription opioids had an elevated risk of any mood outcome (adjusted effect size [aES] = 1.80 [95% confidence interval = 1.40–2.30]) and of an anxiety outcome (aES = 1.40 [1.20–1.80]) compared with those who did not use prescription opioids. Associations with depression were small and not significant after adjustment for potential confounders (aES = 1.18 [0.98–1.41]). However, some studies reported an increased risk of depressive symptoms after increased (aES = 1.58 [1.30–1.93]) or prolonged opioid use (aES = 1.49 [1.19–1.86]).

Conclusions

Mental health should be considered when opioids are prescribed because some patients could be vulnerable to adverse mental health outcomes.

MeCP2 Epigenetic Silencing of Oprm1 Gene in Primary Sensory Neurons Under Neuropathic Pain Conditions

Opioids are the last option for the pharmacological treatment of neuropathic pain, but their antinociceptive effects are limited. Decreased mu opioid receptor (MOR) expression in the peripheral nervous system may contribute to this. Here, we showed that nerve injury induced hypermethylation of the Oprm1 gene promoter and an increased expression of methyl-CpG binding protein 2 (MeCP2) in injured dorsal root ganglion (DRG). The downregulation of MOR in the DRG is closely related to the augmentation of MeCP2, an epigenetic repressor, which could recruit HDAC1 and bind to the methylated regions of the Oprm1 gene promoter. MeCP2 knockdown restored the expression of MOR in injured DRG and enhanced the analgesic effect of morphine, while the mimicking of this increase via the intrathecal infusion of viral vector-mediated MeCP2 was sufficient to reduce MOR in the DRG. Moreover, HDAC1 inhibition with suberoylanilide hydroxamic acid, an HDAC inhibitor, also prevented MOR reduction in the DRG of neuropathic pain mice, contributing to the augmentation of morphine analgesia effects. Mechanistically, upregulated MeCP2 promotes the binding of a high level of HDCA1 to hypermethylated regions of the Oprm1 gene promoter, reduces the acetylation of histone H3 (acH3) levels of the Oprm1 gene promoter, and attenuates Oprm1 transcription in injured DRG. Thus, upregulated MeCP2 and HDAC1 in Oprm1 gene promoter sites, negatively regulates MOR expression in injured DRG, mitigating the analgesic effect of the opioids. Targeting MeCP2/HDAC1 may thus provide a new solution for improving the therapeutic effect of opioids in a clinical setting.

Effectiveness of Oxycodone Hydrochloride (Strong Opioid) vs Combination Acetaminophen and Codeine (Mild Opioid) for Subacute Pain After Fractures Managed Surgically: A Randomized Clinical Trial

IMPORTANCE

Patients with a surgically managed fracture are commonly discharged from the hospital with a strong opioid prescription, but limited evidence exists to support this practice.

OBJECTIVE

To test the hypothesis that strong opioids provide greater analgesia than mild opioids over the first week postdischarge from hospital after fracture surgical treatment.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind, superiority, randomized clinical trial was conducted at a single-center, major trauma hospital in Sydney, Australia. Participants were inpatients who had sustained an acute nonpathological facture of a long bone or the pelvis, patella, calcaneus, or talus who were treated with surgical fixation and enrolled from July 27, 2016, to August 22, 2017. Data were analyzed from June through October 2018.

INTERVENTIONS

Initiation at discharge of oxycodone hydrochloride 5 mg of 10 mg (ie, 1 or 2 tablets) or combination acetaminophen and codeine 500 mg and 8 mg or 1000 mg and 16 mg (ie, 1 or 2 tablets) 4 times daily for a maximum duration of 3 weeks.

MAIN OUTCOMES AND MEASURES

The primary outcome was the mean of daily pain scores collected during week 1 of treatment measured using the Numerical Pain Rating Scale (NRS). Participants were asked to rate their mean pain over the previous 24 hours daily using an NRS score from 0 to 10, with 0 representing no pain and 10 representing the worst pain imaginable. The key secondary outcomes were EuroQol 5-Dimension 5-Level Questionnaire (EQ-5D-5L) responses, worst pain, medication adverse events, global perceived effect, and return to work.

RESULTS

A total of 120 patients with 1 or more acute orthopedic fractures requiring surgical fixation were randomized, including 59 patients in the strong-opioid group (43 [72.9%] men; mean [SD] age, 36.0 [14.1] years; mean oral morphine equivalent for days 1-7 of 32.9 mg) and 61 patients in the mild opioid group (47 [77.1%] men; mean [SD] age, 38.2 [13.5] years; mean oral morphine equivalent for days 1-7 of 5.5 mg). From days 1 to 7 postdischarge, the mean daily NRS mean pain score was 4.04 (95% Cl, 3.67 to 4.41) in the strong opioid group and 4.54 (95% Cl, 4.17 to 4.90) in the mild opioid group. The between-group difference of the primary outcome was not statistically significant (-0.50 [95% Cl, -1.11 to 0.12]; P = .11) despite a 6-fold increased dose of opioids being delivered in the strong opioid group.

CONCLUSIONS AND RELEVANCE

This study found that treatment with strong opioid medication subacutely was not superior to treatment with milder medication for treatment of pain among patients with surgically managed orthopedic fractures. These findings suggest that ongoing first-line strong opioid use after discharge from the hospital should not be supported.

TRIAL REGISTRATION

Australia New Zealand Clinical Trial Registry No.: ACTRN12616000941460.

Shedding Light on the Pharmacological Interactions between μ-Opioid Analgesics and Angiotensin Receptor Modulators: A New Option for Treating Chronic Pain

The current protocols for neuropathic pain management include µ-opioid receptor (MOR) analgesics alongside other drugs; however, there is debate on the effectiveness of opioids. Nevertheless, dose escalation is required to maintain their analgesia, which, in turn, contributes to a further increase in opioid side effects. Finding novel approaches to effectively control chronic pain, particularly neuropathic pain, is a great challenge clinically. Literature data related to pain transmission reveal that angiotensin and its receptors (the AT1R, AT2R, and MAS receptors) could affect the nociception both in the periphery and CNS. The MOR and angiotensin receptors or drugs interacting with these receptors have been independently investigated in relation to analgesia. However, the interaction between the MOR and angiotensin receptors has not been excessively studied in chronic pain, particularly neuropathy. This review aims to shed light on existing literature information in relation to the analgesic action of AT1R and AT2R or MASR ligands in neuropathic pain conditions. Finally, based on literature data, we can hypothesize that combining MOR agonists with AT1R or AT2R antagonists might improve analgesia.

Opioids and Gabapentinoids Utilisation and Their Related-Mortality Trends in the United Kingdom Primary Care Setting, 2010-2019: A Cross-National, Population-Based Comparison Study

Background: There is growing concern over the increasing utilisation trends of opioids and gabapentinoids across but there is lack of data assessing and comparing the utilisation trends across the four United Kingdom countries. We assessed/compared opioids and gabapentinoids utilisation trends across the four United Kingdom countries then evaluated the correlation between their utilisation with related mortality.

Methods: This repeated cross-national study used Prescription Cost Analysis (PCA) datasets (2010–2019). Opioids and gabapentinoids utilisation were measured using number of items dispensed/1,000 inhabitants and defined daily doses (DDDs)/1,000 inhabitant/day. Number of Opioids and gabapentinoids-related mortality were extracted from the United Kingdom Office for National Statistics (2010–2018). Data were analysed using descriptive statistics including linear trend analysis; correlation between the Opioids and gabapentinoids utilisation and their related mortality using Pearson correlation coefficient.

Results: The results illustrated an overall significant increasing trend in the utilisation of opioids (12.5–14%) and gabapentinoids (205–207%) with substantial variations among the four United Kingdom countries. For opioids, Scotland had the highest level of number of items dispensed/1,000 inhabitant (156.6% higher compared to the lowest level in England), whereas in terms of DDD/1,000 inhabitant/day, NI had the highest level. Utilisation trends increased significantly across the four countries ranging from 7.7% in Scotland to 20.5% in NI (p < 0.001). Similarly, for gabapentinoids, there were significant increasing trends ranging from 126.5 to 114.9% in NI to 285.8–299.6% in Wales (p < 0.001) for number of items/1,000 inhabitants and DDD/1,000 inhabitant/day, respectively. Although the utilisation trends levelled off after 2016, this was not translated into comparable reduction in opioids and gabapentinoids-related mortality as the latter continued to increase with the highest level in Scotland (3.5 times more deaths in 2018 compared to England- 280.1 vs. 79.3 deaths/million inhabitants). There were significant moderate-strong positive correlations between opioids and gabapentinoids utilisation trends and their related mortality.

Conclusion: The utilisation trends of opioids and gabapentinoids have increased significantly with substantial variations among the four United Kingdom countries. This coincided with significant increase in their related mortality. Our findings support the call for immediate actions including radical changes in official United Kingdom policies on drug use and effective strategies to promote best clinical practice in opioids and gabapentinoids prescribing.

American Society of Hematology 2020 guidelines for sickle cell disease: management of acute and chronic pain

BACKGROUND

The management of acute and chronic pain for individuals living with sickle cell disease (SCD) is a clinical challenge. This reflects the paucity of clinical SCD pain research and limited understanding of the complex biological differences between acute and chronic pain. These issues collectively create barriers to effective, targeted interventions. Optimal pain management requires interdisciplinary care.

OBJECTIVE

These evidence-based guidelines developed by the American Society of Hematology (ASH) are intended to support patients, clinicians, and other health care professionals in pain management decisions for children and adults with SCD.

METHODS

ASH formed a multidisciplinary panel, including 2 patient representatives, that was thoroughly vetted to minimize bias from conflicts of interest. The Mayo Evidence-Based Practice Research Program supported the guideline development process, including updating or performing systematic reviews. Clinical questions and outcomes were prioritized according to importance for clinicians and patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used, including GRADE evidence-to-decision frameworks, to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel reached consensus on 18 recommendations specific to acute and chronic pain. The recommendations reflect a broad pain management approach, encompassing pharmacological and nonpharmacological interventions and analgesic delivery.

CONCLUSIONS

Because of low-certainty evidence and closely balanced benefits and harms, most recommendations are conditional. Patient preferences should drive clinical decisions. Policymaking, including that by payers, will require substantial debate and input from stakeholders. Randomized controlled trials and comparative-effectiveness studies are needed for chronic opioid therapy, nonopioid therapies, and nonpharmacological interventions.

Rationalisation of long-term high-dose opioids for chronic pain: development of an intervention and conceptual framework

There has been a large increase in the number of prescriptions for opioid drugs in the United Kingdom over the last 20 years or more and the prescribing of opioids in high doses continues to increase. Much opioid prescribing is for chronic non-cancer pain (CNCP) despite serious doubts about the long-term effectiveness of opioids for this indication. Clinical experience is that there are increasing numbers of patients who are on high dosages of opioid drugs over sustained periods which provide limited or no pain relief while having significant negative effects on functioning and quality of life. The aim of this article is to bring readers' attention to some clinical observations of the CNCP population with high doses and to describe an intervention to reduce these doses. Many of these patients have no clinical features of addiction; we suggest that those who show little or no substance misuse behaviours are best understood as a distinct clinical population who have different treatment needs. In order to understand and treat these patients, a model is required which, rather than seeing the problem as lying solely with the patient, focuses on the interaction between the individual and his or her environment and seeks a change in what the patient does every day, rather than a simple, and largely unattainable, goal of symptom elimination. The clinician authors worked together to develop an intervention based upon approaches taken from both pain management and psychiatric practice. A detailed description of this rapid opioid reduction intervention (RORI) is provided along with some preliminary outcome data.

Toward Fair and Humane Pain Policy

Pain policy is not drug policy. If society wants to improve the lives of people in pain and compress the terrible inequalities in its diagnosis and treatment, we have to tailor policy to the root causes driving our problems in treating pain humanely and equitably. In the United States, we do not. Instead, we have proceeded to conflate drug policy with pain policy, relying on arguably magical thinking for the conclusion that by addressing the drug overdose crisis, we are simultaneously addressing the pain crisis. This is a category error, decades of commitment to which have resulted mostly in a worsening of both public health problems. Disentangling our problems in treating pain fairly and equitably from our problems with drugs and substance use is the only path to humane and ethical policy for each.

Examining correlations between opioid dispensing and opioid-related hospitalizations in Canada, 2007-2016

BACKGROUND

High levels of opioid-related mortality, as well as morbidity, contribute to the excessive opioid-related disease burden in North America, induced by high availability of opioids. While correlations between opioid dispensing levels and mortality outcomes are well-established, fewer evidence exists on correlations with morbidity (e.g., hospitalizations).

METHODS

We examined possible overtime correlations between medical opioid dispensing and opioid-related hospitalizations in Canada, by province, 2007-2016. For dispensing, we examined annual volumes of medical opioid dispensing derived from a representative, stratified sample of retail pharmacies across Canada. Raw dispensing information for 'strong opioids' was converted into Defined Daily Doses per 1000 population per day (DDD/1000/day). Opioid-related hospitalization rates referred to opioid poisoning-related admissions by province, for fiscal years 2007-08 to 2016-17, drawn from the national Hospital Morbidity Database. We assessed possible correlations between opioid dispensing and hospitalizations by province using the Pearson product moment correlation; correlation values (r) and confidence intervals were reported.

RESULTS

Significant correlations for overtime correlations between population-levels of opioid dispensing and opioid-related hospitalizations were observed for three provinces: Quebec (r = 0.87, CI: 0.49-0.97; p = 0.002); New Brunswick (r = 0.85;CI: 0.43-0.97; p = 0.004) and Nova Scotia (r = 0.78; CI:0.25-0.95; p = 0.012), with an additional province, Saskatchewan, (r = 0.073; CI:-0.07-0.91;p = 0.073) featuring borderline significance.

CONCLUSIONS

The correlations observed further add to evidence on opioid dispensing levels as a systemic driver of population-level harms. Notably, correlations were not identified principally in provinces with reported high contribution levels (> 50%) of illicit opioids to mortality, which are not captured by dispensing data and so may have distorted or concealed potential correlation effects due to contamination.

Work Environment Factors and Prevention of Opioid-Related Deaths

Opioid use disorder (OUD) and opioid overdose deaths (OODs) are prevalent among US workers, but work-related factors have not received adequate attention as either risk factors or opportunities for OOD prevention. Higher prevalence of OOD in those with heavy physical jobs, more precarious work, and limited health care benefits suggest work environment and organizational factors may predispose workers to the development of OUD.Organizational policies that reduce ergonomic risk factors, respond effectively to employee health and safety concerns, provide access to nonpharmacologic pain management, and encourage early substance use treatment are important opportunities to improve outcomes. Organizational barriers can limit disclosure of pain and help-seeking behavior, and opioid education is not effectively integrated with workplace safety training and health promotion programs.Policy development at the employer, government, and association levels could improve the workplace response to workers with OUD and reduce occupational risks that may be contributing factors.

Factors associated with the prescribing of high-dose opioids in primary care: a systematic review and meta-analysis

BACKGROUND

The risks of harms from opioids increase substantially at high doses, and high-dose prescribing has increased in primary care. However, little is known about what leads to high-dose prescribing, and studies exploring this have not been synthesized. We, therefore, systematically synthesized factors associated with the prescribing of high-dose opioids in primary care.

METHODS

We conducted a systematic review of observational studies in high-income countries that used patient-level primary care data and explored any factor(s) in people for whom opioids were prescribed, stratified by oral morphine equivalents (OME). We defined high doses as ≥ 90 OME mg/day. We searched MEDLINE, Embase, Web of Science, reference lists, forward citations, and conference proceedings from database inception to 5 April 2019. Two investigators independently screened studies, extracted data, and appraised the quality of included studies using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. We pooled data on factors using random effects meta-analyses and reported relative risks (RR) or mean differences with 95% confidence intervals (CI) where appropriate. We also performed a number needed to harm (NNT_H) calculation on factors when applicable.

RESULTS

We included six studies with a total of 4,248,119 participants taking opioids, of whom 3.64% (n = 154,749) were taking high doses. The majority of included studies (n = 4) were conducted in the USA, one in Australia and one in the UK. The largest study (n = 4,046,275) was from the USA. Included studies were graded as having fair to good quality evidence. The co-prescription of benzodiazepines (RR 3.27, 95% CI 1.32 to 8.13, I² = 99.9%), depression (RR 1.38, 95% CI 1.27 to 1.51, I² = 0%), emergency department visits (RR 1.53, 95% CI 1.46 to 1.61, I² = 0%, NNT_H 15, 95% CI 12 to 20), unemployment (RR 1.44, 95% CI 1.27 to 1.63, I² = 0%), and male gender (RR 1.21, 95% CI 1.14 to 1.28, I² = 78.6%) were significantly associated with the prescribing of high-dose opioids in primary care.

CONCLUSIONS

High doses of opioids are associated with greater risks of harms. Associated factors such as the co-prescription of benzodiazepines and depression identify priority areas that should be considered when selecting, identifying, and managing people taking high-dose opioids in primary care. Coordinated strategies and services that promote the safe prescribing of opioids are needed.

STUDY REGISTRATION

PROSPERO, CRD42018088057.

The Modified WHO Analgesic Ladder: Is It Appropriate for Chronic Non-Cancer Pain?

INTRODUCTION

From 1986, the World Health Organization (WHO) analgesic ladder has been used as the simple and valuable pain-relieving guidance in the pharmaceutical pain management, however, with the development of medical history, notions about pain physiology and pain management have already updated. Is the analgesic ladder still appropriate for chronic non-cancer pain (CNCP) patients? This study aims to analyse the current usage of the analgesic ladder in patients with CNCP by evaluating previously published pertinent studies.

METHODS

Literature published in English from January 1980 to April 2019 and cited on PubMed database was included. Analysis on the analgesic ladder, current status of CNCP management, and a new revised ladder model were developed based on relevant literature.

RESULTS

The WHO analgesic ladder for cancer pain is not appropriate for current CNCP management. It is revised into a four-step ladder: the integrative therapies being adopted at each step for reducing or even stopping the use of opioid analgesics; interventional therapies being considered as step 3 before upgrading to strong opioids if non-opioids and weak opioids failed in CNCP management.

DISCUSSION

A simple and valuable guideline in past years, the WHO analgesic ladder is inappropriate for the current use of CNCP control. A revised four-step analgesic ladder aligned with integrative medicine principles and minimally invasive interventions is recommended for control of CNCP.

Risk of opioid misuse in people with cancer and pain and related clinical considerations: a qualitative study of the perspectives of Australian general practitioners

OBJECTIVE

To explore the perspectives of general practitioners (GPs) concerning the risk of opioid misuse in people with cancer and pain and related clinical considerations.

DESIGN

A qualitative approach using semistructured telephone interviews. Analysis used an integrative approach.

SETTING

Primary care.

PARTICIPANTS

Australian GPs with experience of prescribing opioids for people with cancer and pain.

RESULTS

Twenty-two GPs participated, and three themes emerged. Theme 1 (Misuse is not the main problem) contextualised misuse as a relatively minor concern compared with pain control and toxicity, and highlighted underlying systemic factors, including limitations in continuity of care and doctor expertise. Theme 2 ('A different mindset' for cancer pain) captured participants' relative comfort in prescribing opioids for pain in cancer versus non-cancer contexts, and acknowledgement that compassion and greater perceived community acceptance were driving factors, in addition to scientific support for mechanisms and clinical efficacy. Participant attitudes towards prescribing for people with cancer versus non-cancer pain differed most when cancer was in the palliative phase, when they were unconcerned by misuse. Participants were equivocal about the risk-benefit ratio of long-term opioid therapy in the chronic phase of cancer, and were reluctant to prescribe for disease-free survivors. Theme 3 ('The question is always, 'how lazy have you been?') captured participants' acknowledgement that they sometimes prescribed opioids for cancer pain as a default, easier option compared with more holistic pain management.

CONCLUSIONS

Findings highlight the role of specific clinical considerations in distinguishing risk of opioid misuse in the cancer versus non-cancer population, rather than diagnosis per se. Further efforts are needed to ensure continuity of care where opioid prescribing is shared. Greater evidence is needed to guide opioid prescribing in disease-free survivors and the chronic phase of cancer, especially in the context of new treatments for metastatic disease.

Acceptability of a primary care-based opioid and pain review service: a mixed-methods evaluation in England

BACKGROUND

Primary care opioid prescribing to treat chronic non-cancer pain (CNCP) has progressively increased despite a lack of evidence for long-term safety and effectiveness. Developing primary care interventions to reduce opioid dependence in patients with CNCP is a public health priority.

AIM

To report the acceptability of the South Gloucestershire pain and opioid review service for patients with CNCP, which aimed to help patients understand their relationship with prescribed opioids and support non-drug-based pain management strategies.

DESIGN AND SETTING

A mixed-methods evaluation was performed on the service, which was based in two GP practices in South Gloucestershire, England, and delivered by project workers.

METHOD

Descriptive data were collected on delivered-within-service and community-based interventions. Twenty-five semi-structured interviews (n = 18 patients, n = 7 service providers) explored experiences of the service.

RESULTS

The enrolment process, person-centred primary care-based delivery, and service content focused on psychological issues underlying CNCP were found to be acceptable to patients and service providers. Patients welcomed having time to discuss their pain, its management, and related psychological issues. Maintaining a long-term approach was desired as CNCP is a complex issue that takes time to address. GPs recommended that funding was needed to ensure they have dedicated time to support a similar service and to ensure that project workers received adequate clinical supervision.

CONCLUSION

This service model was acceptable and may be a useful means to manage patients with CNCP who develop opioid dependence after long-term use of opioids. A randomised controlled trial is needed to formally test the effectiveness of the service.

ADVERSE EVENTS ASSOCIATED WITH THERAPEUTIC DRY NEEDLING

BACKGROUND

There is a paucity of literature about the adverse events associated with Therapeutic Dry Needling (TDN). Much of the literature surrounding adverse events associated with TDN has been extrapolated from the acupuncture literature. Given that acupuncture and TDN are distinctly different in their application and proposed mechanisms, adverse events associated with TDN should be examined specifically.

PURPOSE

To determine and report the type of adverse events associated with the utilization of TDN.

STUDY DESIGN

Prospective Questionnaire.

METHODS

Four hundred and twenty physical therapists participated in this study. Information related to minor and major adverse events that occurred during 20,464 TDN treatment sessions was collected. Each physical therapist respondent was asked to fill out two weekly self-reported electronic surveys over a six-week period. One survey was related to "minor adverse events" (i.e. pain, bleeding, bruising), while the other was related to "major adverse events" (i.e. pneumothorax, excessive bleeding, prolonged aggravation). Following the six-week period, descriptive statistics were used to describe the adverse events (AE) associated with TDN and calculate the frequencies of those events.

RESULTS

A total of 7,531 minor AE's were reported, indicating that 36.7% of the reported TDN treatments resulted in a minor AE. The top three minor AE's were bleeding (16%), bruising (7.7%), and pain during dry needling (5.9 %). The average ratio of minor AE's for all respondents across all weeks was 0.53 or approximately one event for every two patients. Twenty major AE's were reported out of the 20,494 treatments for a rate of <0.1% (1 per 1,024 TDN treatments). No associations were noted between the frequency of adverse events and the number of patients treated, practitioner age, level of education, years in practice, level of training or months experience with dry needling.

CONCLUSION

Expected minor AE's such as mild bleeding, bruising, and pain during TDN were common and major AE's were rare. Physical therapists and other medical practitioners need to be aware of the risks of TDN. Based on the findings of this study the overall risk of a major adverse event during TDN is small.

LEVEL OF EVIDENCE

3, survey research.

Opioid-sparing effects of 10 kHz spinal cord stimulation: a review of clinical evidence

Chronic pain is a common condition that affects the physical, emotional, and mental well‐being of patients and can significantly diminish their quality of life. Due to growing concerns about the substantial risks of long‐term opioid use, both governmental agencies and professional societies have recommended prioritizing the use of nonpharmacologic treatments, when suitable, in order to reduce or eliminate the need for opioid use. The use of 10 kHz spinal cord stimulation (10 kHz SCS) is one such nonpharmacologic alternative for the treatment of chronic, intractable pain of the trunk and limbs. This review examines published clinical data regarding the efficacy of 10 kHz SCS for decreasing chronic pain in patients and its potential to reduce or eliminate opioid usage. Multiple prospective and retrospective studies in patients with intractable pain demonstrated that 10 kHz SCS treatment provided ≥50% pain relief in >70% patients after at least 1 year of treatment. Pain relief with 10 kHz SCS therapy ranged from 54% to 87% in the studies. More importantly, the mean daily dose of opioids required by patients in these studies was reduced after 10 kHz SCS treatment, and on average over 60% patients in studies either reduced or eliminated opioids at the last follow‐up.

Towards an Effective and Safe Treatment of Inflammatory Pain: A Delphi-Guided Expert Consensus

OBJECTIVE

The clinical management of inflammatory pain requires an optimal balance between effective analgesia and associated safety risks. To date, mechanisms associated with inflammatory pain are not completely understood because of their complex nature and the involvement of both peripheral and central mechanisms. This Expert Consensus document is intended to update clinicians about evolving areas of clinical practice and/or available treatment options for the management of patients with inflammatory pain.

METHOD

An international group of experts in pain management covering the pharmacology, neurology and rheumatology fields carried out an independent qualitative systematic literature search using MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials.

RESULTS

Existing guidelines for pain management provide recommendations that do not satisfactorily address the complex nature of pain. To achieve optimal outcomes, drug choices should be individualized to guarantee the best match between the characteristics of the patient and the properties of the medication. NSAIDs represent an important prescribing choice in the management of inflammatory pain, and the recent results on paracetamol question its appropriate use in clinical practice, raising the need for re-evaluation of the recommendations in the clinical practice guidelines.

CONCLUSIONS

Increasing clinicians' knowledge of the available pharmacologic options to treat different pain mechanisms offers the potential for safe, individualized treatment decisions. We hope that it will help implement the needed changes in the management of inflammatory pain by providing the best strategies and new insights to achieve the ultimate goal of managing the disease and obtaining optimal benefits for patients.

FUNDING

Dompé Farmaceutici SPA and Paolo Procacci Foundation.

10 kHz SCS therapy for chronic pain, effects on opioid usage: Post hoc analysis of data from two prospective studies

Chronic pain, including chronic low back and leg pain are prominent causes of disability worldwide. While patient management aims to reduce pain and improve daily function, prescription of opioids remains widespread despite significant adverse effects. This study pooled data from two large prospective trials on 10 kHz spinal cord stimulation (10 kHz SCS) in subjects with chronic low back pain and/or leg pain and performed post hoc analysis on changes in opioid dosage 12 months post 10 kHz SCS treatment. Patient-reported back and leg pain using the visual analog scale (VAS) and opioid dose (milligrams morphine equivalent/day, MME/day) were compared at 12 months post-10 kHz SCS therapy to baseline. Results showed that in the combined dataset, 39.3% of subjects were taking >90 MME dose of opioids at baseline compared to 23.0% at 12 months post-10 kHz SCS therapy (p = 0.007). The average dose of opioids in >90 MME group was significantly reduced by 46% following 10 kHz SCS therapy (p < 0.001), which was paralleled by significant pain relief (P < 0.001). In conclusion, current analysis demonstrates the benefits of 10 kHz SCS therapy and offers an evidence-based, non-pharmaceutical alternative to opioid therapy and/or an adjunctive therapy to facilitate opioid dose reduction whilst delivering significant pain relief. Healthcare providers involved in management of chronic non-cancer pain can include reduction or elimination of opioid use as part of treatment plan when contemplating 10 kHz SCS.

Prevalent Misconceptions About Opioid Use Disorders in the United States Produce Failed Policy and Public Health Responses

The current opioid crisis in the United States has emerged from higher demand for and prescribing of opioids as chronic pain medication, leading to massive diversion into illicit markets. A peculiar tragedy is that many health professionals prescribed opioids in a misguided response to legitimate concerns that pain was undertreated. The crisis grew not only from overprescribing, but also from other sources, including insufficient research into nonopioid pain management, ethical lapses in corporate marketing, historical stigmas directed against people who use drugs, and failures to deploy evidence-based therapies for opioid addiction and to comprehend the limitations of supply-side regulatory approaches. Restricting opioid prescribing perversely accelerated narco-trafficking of heroin and fentanyl with consequent increases in opioid overdose mortality As injection replaced oral consumption, outbreaks of hepatitis B and C virus and human immunodeficiency virus infections have resulted. This viewpoint explores the origins of the crisis and directions needed for effective mitigation.

Retrospective cohort study of healthcare utilization and opioid use following radiofrequency ablation for chronic axial spine pain in Ontario, Canada

BACKGROUND AND OBJECTIVES

Radiofrequency ablation (RFA) is a common treatment modality for chronic axial spine pain. Controversy exists over its effectiveness, and outcomes in a real-world setting have not been evaluated despite increasing use of RFA. This study examined changes in healthcare utilization and opioid use after RFA in Ontario, Canada.

METHODS

This retrospective cohort study was conducted in Ontario using administrative data. Ontario residents receiving their initial RFA between 1 January 2009 and 31 March 2015 were included. Physician visits, spinal injections, and opioid dosing/prescriptions in the 12-month periods before and after RFA were compared.

RESULTS

The study included 4653 patients. The number of RFA procedures significantly increased from 2009 to 2014 (22.5 cases/1 000 000 person-years to 82.5 cases/1 000 000 person-years). 4465 patients had at least one physician visit pre-RFA; there was a significant 23.89% reduction in physician visits post-RFA (pre-RFA: 29 616 visits; post-RFA: 22 542 visits). All reviewed specialties demonstrated a decrease in physician visits post-RF except neurosurgery. 3445 (85.70%) fewer spinal interventions for axial pain (medial/lateral branch blocks, facet/sacroiliac injections) were performed post-RFA. Significantly fewer epidurals were also performed post-RFA. 198 of 1007 patients (19.66%) on the Ontario Drug Benefit who received opioids pre-RFA did not require a postprocedure opioid prescription. Mean opioid dosing was unchanged post-RFA.

CONCLUSIONS

Healthcare utilization was significantly reduced in the 12 months following RFA, and some patients eliminated opioid use. Selection criteria for RFA are not standardized in Ontario, and appropriate use guidelines for spine interventions may improve outcomes and reduce unnecessary procedures.

Pain Management and Opioid Regulation: Continuing Public Health Challenges

The still-growing US opioid epidemic lies at the intersection of two major public health challenges: reducing suffering from pain and containing the rising toll of harms associated with the use of opioids medications. Responding successfully to these challenges requires a substantial investment in surveillance and research on many fronts and a coordinated policy response by federal and state agencies and stakeholder organizations.A 2017 report of the National Academies of Sciences, Engineering and Medicine (NASEM) called for improved methods of measuring pain and the effects of alternative modalities of treatment as well as intensive surveillance of opioid-related harms; urged a long-term cultural transformation of how pain is perceived, assessed and treated; and outlined a comprehensive and balanced public health framework to guide Food and Drug Administration approval, monitoring, and review of opioids.We, authors of the NASEM report, use the articles published in this special section of AJPH as a platform for commenting on the public health burden of pain, the role of opioids in managing pain, global disparities in access to opioids for pain management, divergent approaches to opioid regulation, and the challenge of striking a reasonable balance between the needs of patients in pain and the prevention of opioid-related harms.

Evidence-Based Pain Management: Building on the Foundations of Cochrane Systematic Reviews

We discuss the history and current status of evidence-based medicine for the prevention and treatment of acute and chronic pain as it has developed in the Cochrane Collaboration's Pain, Palliative and Supportive Care Review Group.To date, the Pain, Palliative and Supportive Care Review Group has published 277 reviews and a further 11 reviews of systematic reviews summarizing the evidence for interventions. The Cochrane Library has readily available high-quality summaries of evidence of pharmacological interventions especially for postsurgical pain but also for chronic musculoskeletal and neuropathic pain. The library covers all forms of intervention, not only pharmacological.The world of evidence-based medicine is changing: most historical trials have been entered into reviews, but the evidence is still not well disseminated and needs to be better translated into decision support. Evidence should be at the heart of policymaking. Much has been achieved in the past 21 years, but there are no grounds for complacency.

Evaluating the early impacts of delisting high-strength opioids on patterns of prescribing in Ontario

INTRODUCTION

Ontario delisted high-strength fentanyl, hydromorphone and morphine from the public drug formulary for non-palliative care prescribers on 31 January, 2017. Our aim is to assess the early impact of this policy on prescribing patterns and to examine whether this impact varied by prescriber type, opioid type and opioid strength.

METHODS

We conducted a population-based, cross-sectional study on palliative and non-palliative care patients dispensed fentanyl, hydromorphone or morphine through the Ontario public drug program between 1 January, 2014, and 31 July, 2017. For each month during the study period, we reported the total number of high-strength opioid recipients stratified by prescriber type, and the total volume of each drug dispensed, stratified by strength. We used interventional autoregressive integrated moving average (ARIMA) models to assess the policy's impact on prescribing patterns.

RESULTS

We observed a 98% decrease in the total number of publicly funded recipients of high-strength opioids between December 2016 and July 2017 (5930 to 133 recipients) for all prescribers. The policy led to a significant decline in the total volume of all three opioids dispensed: hydromorphone from 20 374 621 to 16 952 097 mg (p < .01); morphine from 40 644 190 to 33 555 480 mg (p < .03); and fentanyl from 9 604 913 to 5 842 405 mcg/h (p < .01). For both fentanyl and hydromorphone, this reduction generally corresponded to an increase in the number of low-strength opioids dispensed.

CONCLUSION

Delisting high-strength opioids substantially reduced the number of highstrength opioid recipients and reduced the overall volume of long-acting opioids dispensed in Ontario through the public drug program. Future studies should examine its impact on patient outcomes.

Impact of Dual Use of Department of Veterans Affairs and Medicare Part D Drug Benefits on Potentially Unsafe Opioid Use

OBJECTIVES

To estimate the prevalence and consequences of receiving prescription opioids from both the Department of Veterans Affairs (VA) and Medicare Part D.

METHODS

Among US veterans enrolled in both VA and Part D filling 1 or more opioid prescriptions in 2012 (n = 539 473), we calculated 3 opioid safety measures using morphine milligram equivalents (MME): (1) proportion receiving greater than 100 MME for 1 or more days, (2) mean days receiving greater than 100 MME, and (3) proportion receiving greater than 120 MME for 90 consecutive days. We compared these measures by opioid source.

RESULTS

Overall, 135 643 (25.1%) veterans received opioids from VA only, 332 630 (61.7%) from Part D only, and 71 200 (13.2%) from both. The dual-use group was more likely than the VA-only group to receive greater than 100 MME for 1 or more days (34.3% vs 10.9%; adjusted risk ratio [ARR] = 3.0; 95% confidence interval [CI] = 2.9, 3.1), have more days with greater than 100 MME (42.5 vs 16.9 days; adjusted difference = 16.4 days; 95% CI = 15.7, 17.2), and to receive greater than 120 MME for 90 consecutive days (7.8% vs 3.1%; ARR = 2.2; 95% CI = 2.1, 2.3).

CONCLUSIONS

Among veterans dually enrolled in VA and Medicare Part D, dual use of opioids was associated with more than 2 to 3 times the risk of high-dose opioid exposure.

Adverse events associated with medium- and long-term use of opioids for chronic non-cancer pain: an overview of Cochrane Reviews

BACKGROUND

Chronic pain is common and can be challenging to manage. Despite increased utilisation of opioids, the safety and efficacy of long-term use of these compounds for chronic non-cancer pain (CNCP) remains controversial. This overview of Cochrane Reviews complements the overview entitled 'High-dose opioids for chronic non-cancer pain: an overview of Cochrane Reviews'.

OBJECTIVES

To provide an overview of the occurrence and nature of adverse events associated with any opioid agent (any dose, frequency, or route of administration) used on a medium- or long-term basis for the treatment of CNCP in adults.

METHODS

We searched the Cochrane Database of Systematic Reviews (the Cochrane Library) Issue 3, 2017 on 8 March 2017 to identify all Cochrane Reviews of studies of medium- or long-term opioid use (2 weeks or more) for CNCP in adults aged 18 and over. We assessed the quality of the reviews using the AMSTAR criteria (Assessing the Methodological Quality of Systematic Reviews) as adapted for Cochrane Overviews. We assessed the quality of the evidence for the outcomes using the GRADE framework.

MAIN RESULTS

We included a total of 16 reviews in our overview, of which 14 presented unique quantitative data. These 14 Cochrane Reviews investigated 14 different opioid agents that were administered for time periods of two weeks or longer. The longest study was 13 months in duration, with most in the 6- to 16-week range. The quality of the included reviews was high using AMSTAR criteria, with 11 reviews meeting all 10 criteria, and 5 of the reviews meeting 9 out of 10, not scoring a point for either duplicate study selection and data extraction, or searching for articles irrespective of language and publication type. The quality of the evidence for the generic adverse event outcomes according to GRADE ranged from very low to moderate, with risk of bias and imprecision being identified for the following generic adverse event outcomes: any adverse event, any serious adverse event, and withdrawals due to adverse events. A GRADE assessment of the quality of the evidence for specific adverse events led to a downgrading to very low- to moderate-quality evidence due to risk of bias, indirectness, and imprecision.We calculated the equivalent milligrams of morphine per 24 hours for each opioid studied (buprenorphine, codeine, dextropropoxyphene, dihydrocodeine, fentanyl, hydromorphone, levorphanol, methadone, morphine, oxycodone, oxymorphone, tapentadol, tilidine, and tramadol). In the 14 Cochrane Reviews providing unique quantitative data, there were 61 studies with a total of 18,679 randomised participants; 12 of these studies had a cross-over design with two to four arms and a total of 796 participants. Based on the 14 selected Cochrane Reviews, there was a significantly increased risk of experiencing any adverse event with opioids compared to placebo (risk ratio (RR) 1.42, 95% confidence interval (CI) 1.22 to 1.66) as well as with opioids compared to a non-opioid active pharmacological comparator, with a similar risk ratio (RR 1.21, 95% CI 1.10 to 1.33). There was also a significantly increased risk of experiencing a serious adverse event with opioids compared to placebo (RR 2.75, 95% CI 2.06 to 3.67). Furthermore, we found significantly increased risk ratios with opioids compared to placebo for a number of specific adverse events: constipation, dizziness, drowsiness, fatigue, hot flushes, increased sweating, nausea, pruritus, and vomiting.There was no data on any of the following prespecified adverse events of interest in any of the included reviews in this overview of Cochrane Reviews: addiction, cognitive dysfunction, depressive symptoms or mood disturbances, hypogonadism or other endocrine dysfunction, respiratory depression, sexual dysfunction, and sleep apnoea or sleep-disordered breathing. We found no data for adverse events analysed by sex or ethnicity.

AUTHORS' CONCLUSIONS

A number of adverse events, including serious adverse events, are associated with the medium- and long-term use of opioids for CNCP. The absolute event rate for any adverse event with opioids in trials using a placebo as comparison was 78%, with an absolute event rate of 7.5% for any serious adverse event. Based on the adverse events identified, clinically relevant benefit would need to be clearly demonstrated before long-term use could be considered in people with CNCP in clinical practice. A number of adverse events that we would have expected to occur with opioid use were not reported in the included Cochrane Reviews. Going forward, we recommend more rigorous identification and reporting of all adverse events in randomised controlled trials and systematic reviews on opioid therapy. The absence of data for many adverse events represents a serious limitation of the evidence on opioids. We also recommend extending study follow-up, as a latency of onset may exist for some adverse events.

Morphine for chronic neuropathic pain in adults

BACKGROUND

Neuropathic pain, which is caused by a lesion or disease affecting the somatosensory system, may be central or peripheral in origin. Neuropathic pain often includes symptoms such as burning or shooting sensations, abnormal sensitivity to normally painless stimuli, or an increased sensitivity to normally painful stimuli. Neuropathic pain is a common symptom in many diseases of the nervous system. Opioid drugs, including morphine, are commonly used to treat neuropathic pain. Most reviews have examined all opioids together. This review sought evidence specifically for morphine; other opioids are considered in separate reviews.

OBJECTIVES

To assess the analgesic efficacy and adverse events of morphine for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase for randomised controlled trials from inception to February 2017. We also searched the reference lists of retrieved studies and reviews, and online clinical trial registries.

SELECTION CRITERIA

We included randomised, double-blind trials of two weeks' duration or longer, comparing morphine (any route of administration) with placebo or another active treatment for neuropathic pain, with participant-reported pain assessment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with substantial pain relief (at least 50% pain relief over baseline or very much improved on Patient Global Impression of Change scale (PGIC)), or moderate pain relief (at least 30% pain relief over baseline or much or very much improved on PGIC). Where pooled analysis was possible, we used dichotomous data to calculate risk ratio (RR) and number needed to treat for an additional beneficial outcome (NNT) or harmful outcome (NNH). We assessed the quality of the evidence using GRADE and created 'Summary of findings' tables.

MAIN RESULTS

We identified five randomised, double-blind, cross-over studies with treatment periods of four to seven weeks, involving 236 participants in suitably characterised neuropathic pain; 152 (64%) participants completed all treatment periods. Oral morphine was titrated to maximum daily doses of 90 mg to 180 mg or the maximum tolerated dose, and then maintained for the remainder of the study. Participants had experienced moderate or severe neuropathic pain for at least three months. Included studies involved people with painful diabetic neuropathy, chemotherapy-induced peripheral neuropathy, postherpetic neuralgia criteria, phantom limb or postamputation pain, and lumbar radiculopathy. Exclusions were typically people with other significant comorbidity or pain from other causes.Overall, we judged the studies to be at low risk of bias, but there were concerns over small study size and the imputation method used for participants who withdrew from the studies, both of which could lead to overestimation of treatment benefits and underestimation of harm.There was insufficient or no evidence for the primary outcomes of interest for efficacy or harm. Four studies reported an approximation of moderate pain improvement (any pain-related outcome indicating some improvement) comparing morphine with placebo in different types of neuropathic pain. We pooled these data in an exploratory analysis. Moderate improvement was experienced by 63% (87/138) of participants with morphine and 36% (45/125) with placebo; the risk difference (RD) was 0.27 (95% confidence interval (CI) 0.16 to 0.38, fixed-effects analysis) and the NNT 3.7 (2.6 to 6.5). We assessed the quality of the evidence as very low because of the small number of events; available information did not provide a reliable indication of the likely effect, and the likelihood that the effect will be substantially different was very high. A similar exploratory analysis for substantial pain relief on three studies (177 participants) showed no difference between morphine and placebo.All-cause withdrawals in four studies occurred in 16% (24/152) of participants with morphine and 12% (16/137) with placebo. The RD was 0.04 (-0.04 to 0.12, random-effects analysis). Adverse events were inconsistently reported, more common with morphine than with placebo, and typical of opioids. There were two serious adverse events, one with morphine, and one with a combination of morphine and nortriptyline. No deaths were reported. These outcomes were assessed as very low quality because of the limited number of participants and events.

AUTHORS' CONCLUSIONS

There was insufficient evidence to support or refute the suggestion that morphine has any efficacy in any neuropathic pain condition.