Controlled-release oxycodone and naloxone in the treatment of chronic low back pain: a placebo-controlled, randomized study

Identification of Plasma Metabolites Responding to Oxycodone Exposure in Rats

BACKGROUND

Oxycodone has an elevated abuse liability profile compared to other prescription opioid medications. However, many human and rodent metabolomics studies have not been specifically focused on oxycodone.

OBJECTIVES

Investigating metabolomics changes associated with oxycodone exposure can provide insights into biochemical mechanisms of the addiction cycle and prognosis prediction.

METHODS

Plasma samples from 16 rats at pre-exposure and intoxication time points were profiled on the Metabolon platform. A total of 941 metabolites were characterized. We employed a k-Nearest Neighbor imputation to impute metabolites with low levels of missingness and binarized metabolites with moderate levels of missingness, respectively.

RESULTS

Of the 136 binarized metabolites, 6 showed differential abundance (FDR < 0.05), including 5 that were present at pre-exposure but absent at intoxication (e.g., adenine), while linoleamide (18:2n6) exhibited the opposite behavior. Among the 798 metabolites with low levels of missingness, 364 showed significant changes between pre-exposure and intoxication (FDR < 0.01), including succinate, oleamide, and sarcosine. We identified four pathways, including tryptophan metabolism, that were nominally enriched among the metabolites that change with oxycodone exposure (p < 0.05). Furthermore, we identified several metabolites that showed nominal correlations with the Addiction Index (composite of oxycodone behaviors): 17 at pre-exposure and 8 at intoxication. In addition, the changes in abundance between pre-exposure and intoxication time points of 9 metabolites were nominally correlated with the Addiction Index, including sphingomyelins, methylhistidines, and glycerols.

CONCLUSIONS

In summary, not only were we able to capture oxy-induced changes in metabolic pathways using easily accessible blood samples, but we also demonstrated the potential of blood metabolomics to better understand addiction liability.

Effects of pharmacotherapy on sleep-related outcomes in adults with chronic low back pain: A systematic review and meta-analysis of randomised controlled trials

Background

Adults with chronic low back pain (CLBP) suffer impaired sleep. Medications for CLBP can impact sleep which in turn may influence treatment outcomes. This systematic review and meta-analysis examined the effects of pharmacotherapy (any type) on sleep in adults with CLBP.

Methods

In this systematic review and meta-analysis, we searched PubMed, CINAHL, SPORTDiscus, PsycINFO, EMBASE, and CENTRAL from inception to 10 July 2022. Randomised controlled trials that investigated the effects of pharmacotherapy on sleep in adults with CLBP were included. Manual citation search of relevant systematic reviews and included studies were also conducted. Mean change from baseline for sleep outcomes (e.g., sleep quality, total sleep time, wake after sleep onset) was the effect of interest. Pairwise inverse-variance random effect meta-analysis was performed to impute pooled estimates (Hedges' g or risk ratios). The Hartung-Knapp-Sidik-Jonkman method was used where there were ≤5 studies. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was used for evaluating the certainty of evidence. This study was registered with PROSPERO (CRD42022309419).

Findings

Assessment of 3959 records resulted in nine studies (n = 2927) being included. Pharmacotherapy for CLBP management had a small, yet unlikely clinically significant, effect on improving sleep in adults with CLBP, when compared to placebo (g [95% CI]: -0.23 [-0.37, -0.09], p = .0009; I 2  = 30.1%; n = 1433; studies: n = 8; GRADE: low). Notably, no eligible studies investigated the effect of sleep medications in this population, despite being within the scope of this review.

Interpretation

Pharmacotherapy used to manage CLBP provided improvements in sleep in adults with CLBP. Given that these effects were small and unlikely clinically significant, clinicians could consider alternative treatments (e.g., non-pharmacological interventions) for managing sleep in adults with CLBP. However, low to very low certainty of evidence precluded strong conclusions. To improve certainty of evidence and confidence in the effect estimates, future research needs to use robust method to minimise bias. Additional research evaluating multiple sleep characteristics, using both validated objective and subjective measures, is also warranted to further investigate the influence of distinct sleep parameters.

Funding

The Summer Research Scholarship from the Appleton Institute, Central Queensland University, Australia.

An Updated Overview of Low Back Pain Management

We aimed to determine the recommendation level for the treatment of acute and chronic low back pain (LBP). A systematic review (SR) of the literature was performed and all English-language articles that discuss acute and chronic LBP, including MEDLINE and the Cochrane Database of Systematic Reviews, were searched. Of the 873 searched literature reports, 259 articles, including 131 clinical trials, 115 SRs, nine meta-analyses, and four clinical guidelines were analyzed. In these articles, high-quality randomized controlled trials, SRs, and used well-written clinical guidelines were reviewed. The results indicated multiple acute and chronic LBP treatment methods in the literature, and these reports when reviewed included general behavior, pharmacological therapy, psychological therapy, specific exercise, active rehabilitation and educational interventions, manual therapy, physical modalities, and invasive procedures. The Trial conclusions and SRs were classified into four categories of A, B, C, and D. If there were not enough high-quality articles, it was designated as "I" (insufficient). This review and summary of guidelines may be beneficial for physicians to better understand and make recommendations in primary care.

Benefits and harms of treatments for chronic non-specific low back pain without radiculopathy: Systematic review and meta-analysis

BACKGROUND CONTEXT

Currently, there are no published studies that compare non-pharmacological, pharmacological and invasive treatments for chronic low back pain in adults and provide summary statistics for benefits and harms.

PURPOSE

The aim of this review was to compare the benefits and harms of treatments for the management of chronic low back pain without radiculopathy and to report the findings in a format that facilitates direct comparison (Benefit-Harm Scale: level 1 to 7).

DESIGN

Systematic review and meta-analysis of randomized controlled trials, including trial registries, from electronic databases up to 23^rd May 2022.

PATIENT SAMPLE

Adults with non-specific chronic low back pain, excluding radicular pain in any clinical setting.

OUTCOME MEASURES

Comparison of pain at immediate-term (≤2 weeks) and short-term (>2 weeks to ≤12 weeks) and serious adverse events using the Benefit-Harm Scale (level 1 to 7).

METHODS

This was a registered systematic review and meta-analysis of randomized controlled trials. Interventions included non-pharmacological (acupuncture, spinal manipulation), pharmacological and invasive treatments compared to placebo. Best evidence criteria was used. Two independent reviewers conducted eligibility assessment, data extraction and quality appraisal.

RESULTS

The search retrieved 17,362 records. Three studies provided data on the benefits of interventions, and 30 provided data on harms. Studies included interventions of acupuncture (n=8); manipulation (n=2); pharmacological therapies (n=9), including NSAIDs and opioid analgesics; surgery (n=8); and epidural corticosteroid injections (n=3). Acupuncture (standardized mean difference (SMD) -0.51, 95%CI -0.88 to -0.14, n=1 trial, moderate quality of evidence, benefit rating of 3) and manipulation (SMD -0.39, 95%CI -0.56 to -0.21, n=2 trials, moderate quality of evidence, benefit rating of 5) were effective in reducing pain intensity compared to sham. The benefit of the other interventions was scored as uncertain due to not being effective, statistical heterogeneity preventing pooling of effect sizes, or the absence of relevant trials. The harms level warnings were at the lowest (eg, indicating rarer risk of events) for acupuncture, spinal manipulation, NSAIDs, combination ingredient opioids, and steroid injections, while they were higher for single ingredient opioid analgesics (level 4) and surgery (level 6).

CONCLUSIONS

There is uncertainty about the benefits and harms of all the interventions reviewed due to the lack of trials conducted in patients with chronic non-specific low back pain without radiculopathy. From the limited trials conducted, non-pharmacological interventions of acupuncture and spinal manipulation provide safer benefits than pharmacological or invasive interventions. However, more research is needed. There were high harms ratings for opioids and surgery.

Rescaling pain intensity measures for meta-analyses of analgesic medicines for low back pain appears justified: an empirical examination from randomised trials

OBJECTIVE

Meta-analyses of analgesic medicines for low back pain often rescale measures of pain intensity to use mean difference (MD) instead of standardised mean difference for pooled estimates. Although this improves clinical interpretability, it is not clear whether this method is justified. Our study evaluated the justification for this method.

METHODS

We identified randomised clinical trials of analgesic medicines for adults with low back pain that used two scales with different ranges to measure the same construct of pain intensity. We transformed all data to a 0-100 scale, then compared between-group estimates across pairs of scales with different ranges.

RESULTS

Twelve trials were included. Overall, differences in means between pain intensity measures that were rescaled to a common 0-100 scale appeared to be small and randomly distributed. For one study that measured pain intensity on a 0-100 scale and a 0-10 scale; when rescaled to 0-100, the difference in MD between the scales was 0.8 points out of 100. For three studies that measured pain intensity on a 0-10 scale and 0-3 scale; when rescaled to 0-100, the average difference in MD between the scales was 0.2 points out of 100 (range 5.5 points lower to 2.7 points higher). For two studies that measured pain intensity on a 0-100 scale and a 0-3 scale; when rescaled to 0-100, the average difference in MD between the scales was 0.7 points out of 100 (range 6.2 points lower to 12.1 points higher). Finally, for six studies that measured pain intensity on a 0-100 scale and a 0-4 scale; when rescaled to 0-100, the average difference in MD between the scales was 0.7 points (range 5.4 points lower to 8.3 points higher).

CONCLUSION

Rescaling pain intensity measures may be justified in meta-analyses of analgesic medicines for low back pain. Systematic reviewers may consider this method to improve clinical interpretability and enable more data to be included.

STUDY REGISTRATION/DATA AVAILABILITY

Open Science Framework (osf.io/8rq7f).

Pharmacotherapy for Spine-Related Pain in Older Adults

As the population ages, spine-related pain is increasingly common in older adults. While medications play an important role in pain management, their use has limitations in geriatric patients due to reduced liver and renal function, comorbid medical problems, and polypharmacy. This review will assess the evidence basis for medications used for spine-related pain in older adults, with a focus on drug metabolism and adverse drug reactions. A PubMed/OVID search crossing common spine, neck, and back pain terms with key words for older adults and geriatrics was combined with common drug classes and common drug names and limited to clinical trials and age over 65 years. The results were then reviewed with identification of commonly used drugs and drug categories: nonsteroidal anti-inflammatories (NSAIDs), acetaminophen, corticosteroids, gabapentin and pregabalin, antispastic and antispasmodic muscle relaxants, tricyclic antidepressants (TCAs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tramadol, and opioids. Collectively, 138 double-blind, placebo-controlled trials were the focus of the review. The review found a variable contribution of high-quality studies examining the efficacy of medications for spine pain primarily in the geriatric population. There was strong evidence for NSAID use with adjustments for gastrointestinal and renal risk factors. Gabapentin and pregabalin had mixed evidence for neuropathic pain. SNRIs had good evidence for neuropathic pain and a more favorable safety profile than TCAs. Tramadol had some evidence in older patients, but more so in persons aged < 65 years. Rational therapeutic choices based on geriatric spine pain diagnosis are helpful, such as NSAIDs and acetaminophen for arthritic and myofascial-based pain, gabapentinoids or duloxetine for neuropathic and radicular pain, antispastic agents for myofascial-based pain, and combination therapy for mixed etiologies. Tramadol can be well tolerated in older patients, but has risks of cognitive and classic opioid side effects. Otherwise, opioids are typically avoided in the treatment of spine-related pain in older adults due to their morbidity and mortality risk and are reserved for refractory severe pain. Whenever possible, beneficial geriatric spine pain pharmacotherapy should employ the lowest therapeutic doses with consideration of polypharmacy, potentially decreased renal and hepatic metabolism, and co-morbid medical disorders.

Comparative safety review of current treatment options for chronic low back pain and unmet needs: a narrative review

Introduction: The healthcare expenditures in the United States are substantial for the management of refractory, chronic low back pain (CLBP). The objective of this review is to summarize and evaluate the safety profiles of different pharmacological treatment options used in the management of CLBP.Areas covered: The authors conducted a search of randomized controlled trials (RCTs) assessing the safety profiles of different pharmacological agents used in the management of CLBP. This narrative review covered corticosteroids, opioids, antidepressants, gabapentinoids, nonsteroidal anti-inflammatory drugs, muscle relaxants, anti-nerve growth factor antibodies and topical agents, as monotherapy or in combination.Expert opinion: The risk-benefit ratio of a particular treatment is a subject driving the ongoing development of pharmaceuticals. The most commonly reported AEs across all drug classes are of gastrointestinal nature, followed by neurological and skin-related. These AEs include nausea, dizziness, constipation, arthralgia, headache, dry mouth, pruritus, etc. The majority of the AEs reported are not life-threatening, although they may lower patients' quality of life, thus, affecting their compliance. One of the biggest limitations of our review stems from the paucity of safety assessments in published RCTs. Advances in our understanding of the neurobiology of pain will promote development of new therapeutic strategies.

Physical Compatibility and Chemical Stability of Fentanyl and Naloxone Hydrochloride in 0.9% Sodium Chloride Injection Solution for Patient-Controlled Analgesia Administration

Background and Objective

The combination of naloxone hydrochloride (NH) and fentanyl citrate (FC) in patient-controlled analgesia (PCA) is examined to reduce the risk of opioid-induced nausea and vomiting. However, there are no such commercially available drug mixtures, and there is also no published evidence on the compatibility and stability of NH and FC. Thus, the primary purpose of the current research is to investigate the physical compatibility and chemical stability of NH when mixed with FC over a 72-h period in a 0.9% sodium chloride injection solution for PCA administration under storage at 4°C and 25°C.

Methods

Test solutions of 20 μg/mL FC and 4 μg/mL NH were prepared and stored in polyvinyl chloride (PVC) bags or glass bottles with a 0.9% sodium chloride injection solution as the diluent. During the 72-h storage period at 4°C or 25°C without light protection, the concentrations of the test drugs were assayed via high-performance liquid chromatography (HPLC), and the physical compatibility was determined with the naked eye. Furthermore, pH measurement of each sample was also performed with a pH meter.

Results

The percentages of the initial concentrations of FC and NH in the various solutions were maintained at a minimum of 98% over the 72-h study period. All of the mixtures remained clear and colourless throughout the observation period, and no precipitation or turbidity was observed in any of the batches.

Conclusion

The 20 μg/mL FC test solution was physically compatible and chemically stable with the 4 μg/mL NH test solution when stored at 4°C or 25°C in PVC bags or glass bottles containing the 0.9% sodium chloride injection solution.

Guideline summary review: an evidence-based clinical guideline for the diagnosis and treatment of low back pain

BACKGROUND CONTEXT

The North American Spine Society's (NASS) Evidence Based Clinical Guideline for the Diagnosis and Treatment of Low Back Pain features evidence-based recommendations for diagnosing and treating adult patients with nonspecific low back pain. The guideline is intended to reflect contemporary treatment concepts for nonspecific low back pain as reflected in the highest quality clinical literature available on this subject as of February 2016.

PURPOSE

The purpose of the guideline is to provide an evidence-based educational tool to assist spine specialists when making clinical decisions for adult patients with nonspecific low back pain. This article provides a brief summary of the evidence-based guideline recommendations for diagnosing and treating patients with this condition.

STUDY DESIGN

This is a guideline summary review.

METHODS

This guideline is the product of the Low Back Pain Work Group of NASS' Evidence-Based Clinical Guideline Development Committee. The methods used to develop this guideline are detailed in the complete guideline and technical report available on the NASS website. In brief, a multidisciplinary work group of spine care specialists convened to identify clinical questions to address in the guideline. The literature search strategy was developed in consultation with medical librarians. Upon completion of the systematic literature search, evidence relevant to the clinical questions posed in the guideline was reviewed. Work group members utilized NASS evidentiary table templates to summarize study conclusions, identify study strengths and weaknesses, and assign levels of evidence. Work group members participated in webcasts and in-person recommendation meetings to update and formulate evidence-based recommendations and incorporate expert opinion when necessary. The draft guideline was submitted to an internal and external peer review process and ultimately approved by the NASS Board of Directors.

RESULTS

Eighty-two clinical questions were addressed, and the answers are summarized in this article. The respective recommendations were graded according to the levels of evidence of the supporting literature.

CONCLUSIONS

The evidence-based clinical guideline has been created using techniques of evidence-based medicine and best available evidence to aid practitioners in the diagnosis and treatment of adult patients with nonspecific low back pain. The entire guideline document, including the evidentiary tables, literature search parameters, literature attrition flowchart, suggestions for future research, and all of the references, is available electronically on the NASS website at https://www.spine.org/ResearchClinicalCare/QualityImprovement/ClinicalGuidelines.aspx.

Pharmacovigilance in Hospice/Palliative Care: De-Prescribing Combination Controlled Release Oxycodone-Naloxone

Background: Pharmacovigilance studies in hospice/palliative care provide extra information to improve medication safety. Combination controlled release oxycodone-naloxone offers an alternative opioid with less risk of opioid-induced constipation. Objective: To examine why palliative care clinicians chose to cease oxycodone-naloxone and to explore immediate and short-term benefits and harms of this medication change. Design: A consecutive cohort study. Setting: 112 adults from 13 palliative care centers. Measurements: Reasons for ceasing medication and the harms and benefits that followed this 24 and 72 hours later. Symptom burdens were summarised by the National Cancer Institute Common Terminology Criteria for Adverse Events Toxicity Gradings. Results: Combination medication was most commonly ceased because of poor pain control or impaired hepatic function. The last median oral morphine equivalent oxycodone dose before the switch was 45 mg (range 7.5-240 mg) with 76 switched to an alternative long-acting opioid (initial median oral morphine equivalent dose being 45 mg [range 5-210 mg]). Subgroup analysis of those switched because of clinicians' concerns about hepatic dysfunction demonstrated this group were receiving significantly lower opioid doses pre-cessation compared to those switched because of other reasons( p = 0.007). Regardless of why the medication was changed, improvements in pain and constipation scores were seen, the latter associated with an attendant increase in laxatives. Conclusions: This preliminary work suggests that despite theoretical concerns regarding the effect of the naloxone on opioid doses, most people were switched safely to very similar opioid doses with attendant improvements in pain control.

Efficacy and harms of long-term opioid therapy in chronic non-cancer pain: Systematic review and meta-analysis of open-label extension trials with a study duration ≥26 weeks

BACKGROUND AND OBJECTIVE

This updated systematic review evaluated the efficacy, acceptability and safety of long-term opioid therapy (LTOT) for chronic non-cancer pain (CNCP).

DATABASES AND DATA TREATMENT

Clinicaltrials.gov, CENTRAL and MEDLINE until June 2019. We included open-label extension trials with a study duration ≥26 weeks of RCTs with ≥2 weeks duration. Pooled estimates of event rates of categorical data and standardized mean differences (SMD) of continuous variables were calculated using a random effects model.

RESULTS

We added four new studies with 1,154 participants for a total of 15 studies with 3,590 participants. Study duration ranged between 26 and 156 weeks. Studies included patients with low back, osteoarthritis and neuropathic pain. The quality of evidence for every outcome was very low. 31.1% (95% Confidence interval [CI] 23.0%-40.7%) of patients randomized at baseline finished the open label period. 14.1% (95% CI 10.9%-19.4%) of patients dropped out to due adverse events. In 6.3% (95 CI 3.9%-10.1%) of patients serious adverse events and in 2.7% (95% CI 1.5%-4.7%) aberrant drug behaviour were noted. 0.5% (95% CI 0.2%-1.4%) of patients died.

CONCLUSIONS

Within the context of open-label extension studies, opioids maintain reduction of pain and disability and are rather well tolerated and safe. LTOT can be considered in carefully selected and monitored patients with low back, osteoarthritis and neuropathic pain who experience a clinically meaningful pain reduction with at least tolerable adverse events in short-term opioid therapy.

SIGNIFICANCE

There is very low quality evidence of the long-term efficacy, tolerability and safety of opioids for chronic low back, osteoarthritis and diabetic polyneuropathic pain within the context of open-label extension studies of randomized controlled trials. Drop out rate due to adverse events and deaths increase with study duration. One-third of patients profit from LTOT. Long-term opioid therapy can be considered in some carefully selected and monitored patients.

The role of oxycodone/naloxone in the management of patients with pain and opioid-induced constipation

INTRODUCTION

Common opioid adverse effects (AE) of the gastrointestinal tract include opioid-induced constipation (OIC) and opioid-induced bowel dysfunction (OIBD) with traditional laxatives being of limited efficacy, having AEs and not addressing the pathophysiology of OIC or OIBD. Targeted treatment comprises of PAMORA (peripherally acting mu-opioid receptor antagonists) and a combination of an opioid receptor agonist with its antagonist, namely prolonged-release oxycodone with prolonged-release naloxone (OXN) tablets at a fixed ratio of 2:1. Oxycodone provides analgesia, whereas naloxone prevents binding or displaces it from opioid receptors located in the gut wall. Areas covered: The authors review the role of OXN in the management of patients with pain and OIC. A literature search was performed using the search terms 'oxycodone/naloxone' and 'opioid-induced constipation' using the PubMed database up to October 2018. Expert opinion: OXN delivers analgesia comparable (or superior versus placebo and in observational studies) to oxycodone alone and other opioids with a limited or decreased disturbing effect on bowel function. OXN in daily doses of up to 160 mg/80 mg provides effective analgesia with little negative impact on bowel function. OXN may be successfully used in patients with chronic pain, to prevent or treat symptoms of OIC and OIBD.

Opioids for Chronic Noncancer Pain: A Systematic Review and Meta-analysis

IMPORTANCE

Harms and benefits of opioids for chronic noncancer pain remain unclear.

OBJECTIVE

To systematically review randomized clinical trials (RCTs) of opioids for chronic noncancer pain.

DATA SOURCES AND STUDY SELECTION

The databases of CENTRAL, CINAHL, EMBASE, MEDLINE, AMED, and PsycINFO were searched from inception to April 2018 for RCTs of opioids for chronic noncancer pain vs any nonopioid control.

DATA EXTRACTION AND SYNTHESIS

Paired reviewers independently extracted data. The analyses used random-effects models and the Grading of Recommendations Assessment, Development and Evaluation to rate the quality of the evidence.

MAIN OUTCOMES AND MEASURES

The primary outcomes were pain intensity (score range, 0-10 cm on a visual analog scale for pain; lower is better and the minimally important difference [MID] is 1 cm), physical functioning (score range, 0-100 points on the 36-item Short Form physical component score [SF-36 PCS]; higher is better and the MID is 5 points), and incidence of vomiting.

RESULTS

Ninety-six RCTs including 26 169 participants (61% female; median age, 58 years [interquartile range, 51-61 years]) were included. Of the included studies, there were 25 trials of neuropathic pain, 32 trials of nociceptive pain, 33 trials of central sensitization (pain present in the absence of tissue damage), and 6 trials of mixed types of pain. Compared with placebo, opioid use was associated with reduced pain (weighted mean difference [WMD], -0.69 cm [95% CI, -0.82 to -0.56 cm] on a 10-cm visual analog scale for pain; modeled risk difference for achieving the MID, 11.9% [95% CI, 9.7% to 14.1%]), improved physical functioning (WMD, 2.04 points [95% CI, 1.41 to 2.68 points] on the 100-point SF-36 PCS; modeled risk difference for achieving the MID, 8.5% [95% CI, 5.9% to 11.2%]), and increased vomiting (5.9% with opioids vs 2.3% with placebo for trials that excluded patients with adverse events during a run-in period). Low- to moderate-quality evidence suggested similar associations of opioids with improvements in pain and physical functioning compared with nonsteroidal anti-inflammatory drugs (pain: WMD, -0.60 cm [95% CI, -1.54 to 0.34 cm]; physical functioning: WMD, -0.90 points [95% CI, -2.69 to 0.89 points]), tricyclic antidepressants (pain: WMD, -0.13 cm [95% CI, -0.99 to 0.74 cm]; physical functioning: WMD, -5.31 points [95% CI, -13.77 to 3.14 points]), and anticonvulsants (pain: WMD, -0.90 cm [95% CI, -1.65 to -0.14 cm]; physical functioning: WMD, 0.45 points [95% CI, -5.77 to 6.66 points]).

CONCLUSIONS AND RELEVANCE

In this meta-analysis of RCTs of patients with chronic noncancer pain, evidence from high-quality studies showed that opioid use was associated with statistically significant but small improvements in pain and physical functioning, and increased risk of vomiting compared with placebo. Comparisons of opioids with nonopioid alternatives suggested that the benefit for pain and functioning may be similar, although the evidence was from studies of only low to moderate quality.

An Updated Overview of Low Back Pain Management in Primary Care

Currently, guidelines for lower back pain (LBP) treatment are needed. We reviewed the current guidelines and high-quality articles to confirm the LBP guidelines for the Korean Society of Spine Surgery. We searched available databases for high-quality articles in English on LBP published from 2000 to the present year. Literature searches using these guidelines included studies from MEDLINE, the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, and Embase. We analyzed a total of 132 randomized clinical trials, 116 systematic reviews, 9 meta-analyses, and 4 clinical guideline reviews. We adopted the SIGN checklist for the assessment of article quality. Data were subsequently abstracted by a reviewer and verified. Many treatment options exist for LBP, with a variety of recommendation grades. We assessed the recommendation grade for general behavior, pharmacological therapy, psychological therapy, and specific exercises. This information should be helpful to physicians in the treatment of LBP patients.

[Long-term opioid therapy in chronic noncancer pain. A systematic review and meta-analysis of efficacy, tolerability and safety in open-label extension trials with study duration of at least 26 weeks]

BACKGROUND

The efficacy and safety of long-term (≥ 6 months) opioid therapy (LtOT) in chronic noncancer pain (CNCP) is under debate. A systematic review with meta-analysis of the efficacy and harms of opioids in open-label extension studies of randomized controlled trials (RCTs) has not been conducted until now.

METHODS

We screened MEDLINE and clinicaltrials.gov (through to December 2013), as well as reference sections of systematic reviews of long-term RCTs of opioids in CNCP. We included open-label extension trials with a study duration ≥ 26 weeks of RCTs of ≥ 2 weeks duration. Using a random effects model, pooled estimates of event rates for categorical data and standardized mean differences (SMD) for continuous variables were calculated.

RESULTS

We included 11 open-label extension studies with 2445 participants with nociceptive (low back, osteoarthritis) and neuropathic (radicular, polyneuropathy) pain. Median study duration was 26 (range 26-108) weeks. Four studies tested oxycodone, two studies tramadol and buprenorphine; hydromorphone, morphine, oxymorphone and tapentadol were each tested in one study. Of the patients randomized at baseline, 28.5 % (95 % confidence interval, CI, 17.9-39.2 %) finished the open-label period; 53.5 % (95 % CI 38.1-68.2 %) of patients entering the open-label period finished the open-label period. In sum, the total loss was 71.5 % (95 % CI 60.9-83.1 %) of all patients primarily included into the RCT. A total of 4.9 % (95 % CI 2.9-8.2 %) of patients dropped out due lack of efficacy; 16.8 % (95 % CI 11.0-24.8 %) dropped out to due adverse events (AE) in the open-label period and 0.08 % (95 % CI 0.001-0.05 %) of patients died during the open-label period. Only one study systematically assessed aberrant drug behavior of the patients: 5.7 % (95 % CI 3.4-9.6 %) showed aberrant drug behavior in the opinion of the investigators and 2.6 % (95 % CI 1.2-5.8 %) were judged to show aberrant drug behavior by independent expert assessment. There was no significant change (p = 0.50) in pain intensity between the end of the randomized period and the end of open-label phase (SMD 0.19 [- 0.03, 0.41]; six studies with 1360 participants).

CONCLUSION

Only a minority of patients selected for opioid therapy at randomization finished the long-term open-label study. However, sustained effects of pain reduction could be demonstrated in these patients. LtOT can be considered in carefully selected and monitored CNCP patients who experience clinically meaningful pain reduction with at least tolerable AE in short-term opioid therapy. The English full-text version of this article is freely available at SpringerLink (under "Supplementary Material").

[Opioids in chronic low back pain. A systematic review and meta-analysis of efficacy, tolerability and safety in randomized placebo-controlled studies of at least 4 weeks duration]

BACKGROUND

The efficacy and safety of opioid therapy in chronic low back pain (CLBP) is under debate. We updated a recent systematic review on the efficacy and safety of opioids in CLBP.

METHODS

We screened MEDLINE, Scopus and the Cochrane Central Register of Controlled Trials (CENTRAL) up until October 2013, as well as reference sections of original studies and systematic reviews of randomized controlled trials (RCTs) of opioids in CLBP. We included double-blind randomized placebo-controlled studies of at least 4 weeks duration. Using a random effects model, absolute risk differences (RD) were calculated for categorical data and standardized mean differences (SMD) for continuous variables.

RESULTS

We included 12 RCTs with 17 treatment arms and 4375 participants. Median study duration was 12 (4-16) weeks. Of the 17 treatment arms, seven (41.2 %) used oxycodone; four (23.6 %) tramadol; buprenorphine and oxymorphone were each used in two (11.8 %) and hydromorphone and tapentadol each in one (5.8 %). The results for studies with parallel/cross-over design were as follows (with 95 % confidence interval, CI): opioids were superior to placebo in reducing pain intensity (SMD - 0.29 [- 0.37, - 0.21], p < 0.0001; six studies with 2896 participants). Opioids were superior to placebo in 50 % pain reduction (RD 0.05 [0.01, 0.10], p = 0.01; two studies with 1492 participants; number needed to benefit (NNTB) 19 [95 % CI 10-107]). Opioids were not superior to placebo in reports of much or very much improved pain (RD 0.16 [- 0.01, 0.34], p = 0.07; two studies with 1153 participants). Opioids were superior to placebo in improving physical functioning (SMD - 0.22 [- 0.31, - 0.12], p < 0.0001; four studies with 1895 participants). Patients dropped out less frequently with opioids than with placebo due to lack of efficacy (RD - 0.10 [- 0.16, - 0.04], p = 0.001; five studies with 3168 participants; NNTB 10 [8-13]). Patients dropped out more frequently with opioids than with placebo due to adverse events (RD 0.12 [0.05, 0.19], p = 0.0007; six studies with 2910 participants; number needed to harm (NNTH) 7 [95 % CI 6-8]). There was no significant difference between opioids and placebo in terms of the frequency of serious adverse events or deaths.

CONCLUSION

Opioids were superior to placebo in terms of efficacy and inferior in terms of tolerability. Opioids and placebo did not differ in terms of safety during the study period. The conclusion on the safety of opioids compared to placebo is limited by the low number of serious adverse events and deaths. Short-term and intermediate-term opioid therapy may be considered in selected CLBP patients. The English full-text version of this article is freely available at SpringerLink (under "Supplemental").

Efficacy, Tolerability, and Dose-Dependent Effects of Opioid Analgesics for Low Back Pain: A Systematic Review and Meta-analysis

IMPORTANCE

Opioid analgesics are commonly used for low back pain, however, to our knowledge there has been no systematic evaluation of the effect of opioid dose and use of enrichment study design on estimates of treatment effect.

OBJECTIVE

To evaluate efficacy and tolerability of opioids in the management of back pain; and investigate the effect of opioid dose and use of an enrichment study design on treatment effect.

DATA SOURCES

Medline, EMBASE, CENTRAL, CINAHL, and PsycINFO (inception to September 2015) with citation tracking from eligible randomized clinical trials (RCTs).

STUDY SELECTION

Placebo-controlled RCTs in any language.

DATA EXTRACTION AND SYNTHESIS

Two authors independently extracted data and assessed risk of bias. Data were pooled using a random effects model with strength of evidence assessed using the grading of recommendations assessment, development, and evaluation (GRADE).

MAIN OUTCOMES AND MEASURES

The primary outcome measure was pain. Pain and disability outcomes were converted to a common 0 to 100 scale, with effects greater than 20 points considered clinically important.

RESULTS

Of 20 included RCTs of opioid analgesics (with a total of 7925 participants), 13 trials (3419 participants) evaluated short-term effects on chronic low back pain, and no placebo-controlled trials enrolled patients with acute low back pain. In half of these 13 trials, at least 50% of participants withdrew owing to adverse events or lack of efficacy. There was moderate-quality evidence that opioid analgesics reduce pain in the short term; mean difference (MD), -10.1 (95% CI, -12.8 to -7.4). Meta-regression revealed a 12.0 point greater pain relief for every 1 log unit increase in morphine equivalent dose (P = .046). Clinically important pain relief was not observed within the dose range evaluated (40.0-240.0-mg morphine equivalents per day). There was no significant effect of enrichment study design.

CONCLUSIONS AND RELEVANCE

For people with chronic low back pain who tolerate the medicine, opioid analgesics provide modest short-term pain relief but the effect is not likely to be clinically important within guideline recommended doses. Evidence on long-term efficacy is lacking. The efficacy of opioid analgesics in acute low back pain is unknown.

Impact of prolonged-release oxycodone/naloxone on outcomes affecting patients' daily functioning in comparison with extended-release tapentadol: a systematic review

PURPOSE

The objective of this systematic review was to assess the clinical efficacy, safety, tolerability, and health-related quality of life outcomes associated with management of moderate-to-severe chronic pain with oxycodone/naloxone and tapentadol, focusing on the effect of these treatments on patients' daily functioning.

METHODS

Literature from a wide range of sources, including Embase, MEDLINE, MEDLINE In-Process, and the Cochrane Central Register of Controlled Trials, was searched to identify randomized controlled trials investigating tapentadol or oxycodone/naloxone for the treatment of patients with chronic pain. A network meta-analysis was conducted to determine the relative efficacy and safety profiles of these treatments.

FINDINGS

Oxycodone/naloxone was significantly better than tapentadol with respect to the Patient Assessment of Constipation Symptoms total score (risk ratio = -3.60; 95% credible interval, -5.36 to -2.11) and revealed a significantly lower risk of dizziness (risk ratio = 0.72; 95% credible interval, 0.42-0.98). Oxycodone/naloxone was directionally favored, although not significantly superior to tapentadol for headache, fatigue, dry mouth, dyspepsia, and withdrawals due to lack of efficacy. For the AE outcomes of constipation, nausea, and vomiting, as well as pain efficacy and all-cause withdrawals from studies, tapentadol was directionally favored without any statistical difference from oxycodone/naloxone. However, the two treatments were not wholly comparable for the evaluation of pain efficacy because of differences in on-study rescue medication and a higher baseline pain severity in the tapentadol studies.

IMPLICATIONS

Oxycodone/naloxone offers significant improvements in Patient Assessment of Constipation Symptoms total score and dizziness and was directionally favored for fatigue and headache compared with extended-release tapentadol, which may translate to improved patient daily functioning and health-related quality of life.

Injectable peptide hydrogels for controlled-release of opioids

Peptide-based hydrogels as a drug carrier system for the subcutaneous administration of morphine.

Tolerability, Safety, and Quality of Life with Tapentadol Prolonged Release (PR) Compared with Oxycodone/Naloxone PR in Patients with Severe Chronic Low Back Pain with a Neuropathic Component: A Randomized, Controlled, Open-label, Phase 3b/4 Trial

OBJECTIVE

To evaluate tolerability, safety, and quality-of-life outcomes in non-opioid-pretreated patients with severe chronic low back pain with a neuropathic component receiving tapentadol PR vs. oxycodone/naloxone PR.

METHODS

Eligible patients (average pain intensity [numerical rating scale] ≥ 6; painDETECT positive/unclear ratings) were randomized to twice-daily tapentadol PR 50 mg or oxycodone/naloxone PR 10 mg/5 mg. After a 21-day titration (maximum twice-daily doses: tapentadol PR 250 mg, or oxycodone/naloxone PR 40 mg/20 mg plus oxycodone PR 10 mg), target doses were continued for 9 weeks. Change in the Patient Assessment of Constipation Symptoms (PAC-SYM) total score from baseline to final evaluation was a primary endpoint.

RESULTS

For the primary tolerability-related endpoint, the 97.5% exact repeated confidence interval for tapentadol PR minus oxycodone/naloxone PR for the PAC-SYM total score was [-0.259, 0.121], showing noninferiority (upper limit < 0.7). Incidences of constipation and vomiting were significantly lower with tapentadol PR than oxycodone/naloxone PR (P ≤ 0.045). Confirmatory superiority based on formal noninferiority was shown for the primary effectiveness endpoint (change from baseline to final evaluation in pain intensity) for tapentadol PR vs. oxycodone/naloxone PR (presented separately). Improvements in the Short Form-12 physical component summary and EuroQol-5 Dimension health status index and health state assessment were significantly greater with tapentadol PR vs. oxycodone/naloxone PR (P ≤ 0.024).

CONCLUSIONS

Tapentadol PR had a minimal impact on bowel function (noninferior to oxycodone/naloxone PR) and, along with superior effectiveness (presented separately), was associated with significantly lower incidences of constipation and vomiting and significant improvements in quality-of-life measures vs. oxycodone/naloxone PR.

Strong opioids for noncancer pain due to musculoskeletal diseases: Not more effective than acetaminophen or NSAIDs

The classification of morphine as a step III analgesic, based on pharmacological data, creates a strong bias toward a belief in the efficacy of this drug. However, double-blind emergency-room trials showed similar levels of pain relief with intravenous acetaminophen as with intravenous morphine in patients with renal colic, low back pain or acute limb pain. In patients with chronic noncancer low back pain, morphine and other strong opioids in dosages of up to 100mg/day were only slightly more effective than their placebos, no more effective than acetaminophen, and somewhat less effective than nonsteroidal anti-inflammatory drugs (NSAIDs). In patients with osteoarthritis, strong opioids were not more effective than NSAIDs and, in some studies, than placebos. The only randomized controlled trial in patients with sciatica found no difference with the placebo. Chronic use of strong opioids can induce hyperalgesia in some patients. Hyperpathia with increased sensitivity to cold leading the patient to request higher dosages should suggest opioid-induced hyperalgesia. Pain specialists in the US have issued a petition asking that strong opioids be used in dosages no higher than 100mg/day of morphine-equivalent, in an effort to decrease the high rate of mortality due to the misuse and abuse of strong opioids (10,000 deaths/year in the US). Healthcare providers often overestimate the efficacy of step III analgesics, despite pain score decreases of only 0.8 to 1.2 points.

Effectiveness of Tapentadol Prolonged Release (PR) Compared with Oxycodone/Naloxone PR for the Management of Severe Chronic Low Back Pain with a Neuropathic Component: A Randomized, Controlled, Open-Label, Phase 3b/4 Study

OBJECTIVE

To evaluate the effectiveness of tapentadol prolonged release (PR) vs. oxycodone/naloxone PR in non-opioid-pretreated patients with severe chronic low back pain with a neuropathic pain component.

METHODS

Eligible patients (average pain intensity [numerical rating scale-3 (NRS-3)] ≥6; painDETECT positive/unclear) were randomized to twice-daily tapentadol PR 50 mg or oxycodone/naloxone PR 10 mg/5 mg. After a 21-day titration (maximum twice-daily doses: tapentadol PR 250 mg, or oxycodone/naloxone PR 40 mg/20 mg plus oxycodone PR 10 mg), target doses were continued for 9 weeks. The primary effectiveness endpoint was the change in NRS-3 from baseline to final evaluation; the exact repeated confidence interval (RCI) for tapentadol PR minus oxycodone/naloxone PR was used to establish noninferiority (upper limit <1.3) and superiority (confirmatory analyses).

RESULTS

For the primary effectiveness endpoint, tapentadol PR was noninferior to oxycodone/naloxone PR (97.5% RCI: [-1.820, -0.184]; P < 0.001). This exact RCI also yielded evidence of superiority for tapentadol PR vs. oxycodone/naloxone PR (significantly greater reduction in pain intensity; P = 0.003). Improvements (baseline to final evaluation) in painDETECT and Neuropathic Pain Symptom Inventory scores were significantly greater with tapentadol PR vs. oxycodone/naloxone PR (all P ≤ 0.005).

CONCLUSIONS

The study was formally shown to be positive and demonstrated, in the primary effectiveness endpoint, the noninferiority for tapentadol PR vs. oxycodone/naloxone PR. The effectiveness of tapentadol PR was superior to that of oxycodone/naloxone PR by means of clinical relevance and statistical significance (confirmatory evidence of superiority). Tapentadol PR was associated with significantly greater improvements in neuropathic pain-related symptoms and global health status than oxycodone/naloxone PR and with a significantly better gastrointestinal tolerability profile. Tapentadol PR may be considered a first-line option for managing severe chronic low back pain with a neuropathic pain component.

Emerging therapies for patients with symptoms of opioid-induced bowel dysfunction

Opioid-induced bowel dysfunction (OIBD) comprises gastrointestinal (GI) symptoms, including dry mouth, nausea, vomiting, gastric stasis, bloating, abdominal pain, and opioid-induced constipation, which significantly impair patients’ quality of life and may lead to undertreatment of pain. Traditional laxatives are often prescribed for OIBD symptoms, although they display limited efficacy and exert adverse effects. Other strategies include prokinetics and change of opioids or their administration route. However, these approaches do not address underlying causes of OIBD associated with opioid effects on mostly peripheral opioid receptors located in the GI tract. Targeted management of OIBD comprises purely peripherally acting opioid receptor antagonists and a combination of opioid receptor agonist and antagonist. Methylnaltrexone induces laxation in 50%–60% of patients with advanced diseases and OIBD who do not respond to traditional oral laxatives without inducing opioid withdrawal symptoms with similar response (45%–50%) after an oral administration of naloxegol. A combination of prolonged-release oxycodone with prolonged-release naloxone (OXN) in one tablet (a ratio of 2:1) provides analgesia with limited negative effect on the bowel function, as oxycodone displays high oral bioavailability and naloxone demonstrates local antagonist effect on opioid receptors in the GI tract and is totally inactivated in the liver. OXN in daily doses of up to 80 mg/40 mg provides equally effective analgesia with improved bowel function compared to oxycodone administered alone in patients with chronic non-malignant and cancer-related pain. OIBD is a common complication of long-term opioid therapy and may lead to quality of life deterioration and undertreatment of pain. Thus, a complex assessment and management that addresses underlying causes and patomechanisms of OIBD is recommended. Newer strategies comprise methylnaltrexone or OXN administration in the management of OIBD, and OXN may be also considered as a preventive measure of OIBD development in patients who require opioid administration.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

Oxycodone/Naloxone: role in chronic pain management, opioid-induced constipation, and abuse deterrence

The use of opioids in the treatment of chronic pain is widespread; the prevalence of specific opioids varies from country to country and depends on product availability, national formulary systems, and provider preferences. Patients often receive opioids for legitimate treatment of pain conditions, but on the opposite side of the spectrum, nonmedical use of opioids is a significant public health concern. Opioids are associated with several side effects, and constipation is the most commonly reported and persistent symptom. Unlike some adverse effects associated with opioid use, tolerance does not develop to constipation. Opioid-induced constipation (OIC) is the most prevalent patient complaint associated with opioid use and has been associated with declines in various quality of life measures. OIC can be extremely difficult for patients to tolerate and may prompt patients to decrease or discontinue opioid treatment. Current management strategies for OIC are often insufficient. A prolonged-release formulation of oxycodone/naloxone (OXN) has been investigated for the treatment of nonmalignant and cancer pain and mitigation of OIC, and evidence is largely favorable. Studies have demonstrated the capability of OXN to alleviate OIC while maintaining pain control comparable to oxycodone-only regimens. There is insufficient evidence for OXN efficacy for patients with mild OIC or patients maintained on high doses of opioids, and use in these populations is controversial. The reduction of costs associated with OIC may provide overall cost effectiveness with OXN. Additionally, the presence of naloxone may deter abuse/misuse by those seeking to misuse the formulation by modes of administration other than oral ingestion. Most studies to date have occurred in European countries, and phase 3 trials continue in the United States. This review will include current therapeutic options for pain and constipation, unique characteristics of OXN, evidence related to use of OXN and its place in therapy, discussion of opioid abuse/misuse, and various abuse-deterrent mechanisms, and areas of continuing research.

Effectiveness and tolerability of low-dose oral oxycodone/naloxone added to anticonvulsant therapy for noncancer neuropathic pain: an observational analysis

BACKGROUND

Opioids may alleviate chronic neuropathic pain (NP), but are considered second/third-line analgesia due to their poor gastrointestinal (GI) tolerability. A fixed combination of prolonged-release oxycodone and naloxone (OXN) has been developed to overcome the GI effects. The aim of this analysis was to evaluate analgesic effectiveness and tolerability of low-dose OXN in patients with moderate-to-severe noncancer NP despite analgesia.

METHODS

This retrospective observation of consecutive adult patients, treated open-label for 8 weeks at a single Italian centre, evaluated effectiveness (pain intensity numerical rating scale [NRS], Patients' Global Impression of Change [PGIC], Douleur Neuropathique 4 inventory [DN4] and Chronic Pain Sleep Inventory [CPSI]), doses of daily OXN and adjuvant medication, rescue paracetamol use, bowel function index (BFI), laxative use, and safety.

RESULTS

Of 200 patients (mean age 65.9 years; 54% female) with NP included in the analysis; 97% completed 8 weeks' treatment. At the observation start, all patients were taking anticonvulsants and complained of constipation, and 60% were receiving opioids. Pain intensity and DN4 score decreased significantly by endpoint (NRS p < 0.0001; DN4 p < 0.0001) and need for rescue analgesics abated. Reduction in pain intensity throughout the observation was similar regardless of NP aetiology. According to PGIC, 87.8% of patients were much/extremely improved, CPSI (p < 0.0001) and BFI were significantly improved (p < 0.0001) and laxative use decreased. No differences were found between patients <65 years vs those ≥65 years. OXN was generally well tolerated.

STUDY LIMITATIONS

Study limitations including the retrospective observational design, the lack of a control group and the single-centre design may limit the generalizability of our findings.

CONCLUSIONS

Low-dose OXN (25.0 ± 12.5 mg/day) added to anticonvulsants was highly effective in controlling noncancer NP of varied aetiology, with reduced need for rescue analgesia and improved quality of sleep, and was well tolerated, with improved bowel function and reduced laxative use. The efficacy and tolerability of OXN demonstrated in this real-world setting suggest its utility in this difficult to manage patient population.

Efficacy and gastrointestinal tolerability of oral oxycodone/naloxone combination for chronic pain in outpatients with cancer: an observational study

Combination opioid agonist/antagonist therapy has been shown to preserve bowel function in patients with chronic cancer pain. This retrospective study evaluated the efficacy and tolerability of prolonged-released fixed-dose oxycodone-naloxone (PR OXN) in consecutive outpatients with chronic cancer pain. Of 206 patients prescribed PR OXN (mean age 61.3 ± 12.9 years; 52.9% female), 31.5% were opioid naïve. PR OXN was associated with a significant decrease in pain score measured on a visual analogue scale over 28 days (P < .0001), without adverse effects on bowel function, nor change in laxative use. PR OXN efficacy and tolerability were similar in opioid-naïve and -experienced patients, and among age-stratified subgroups. No severe side effects occurred. In a real-life outpatient setting, PR OXN provided analgesia without bowel dysfunction in patients with chronic cancer pain.

Opioids compared to placebo or other treatments for chronic low-back pain

BACKGROUND

The use of opioids in the long-term management of chronic low-back pain (CLBP) has increased dramatically. Despite this trend, the benefits and risks of these medications remain unclear. This review is an update of a Cochrane review first published in 2007.

OBJECTIVES

To determine the efficacy of opioids in adults with CLBP.

SEARCH METHODS

We electronically searched the Cochrane Back Review Group's Specialized Register, CENTRAL, CINAHL and PsycINFO, MEDLINE, and EMBASE from January 2006 to October 2012. We checked the reference lists of these trials and other relevant systematic reviews for potential trials for inclusion.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that assessed the use of opioids (as monotherapy or in combination with other therapies) in adults with CLBP that were at least four weeks in duration. We included trials that compared non-injectable opioids to placebo or other treatments. We excluded trials that compared different opioids only.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data onto a pre-designed form. We pooled results using Review Manager (RevMan) 5.2. We reported on pain and function outcomes using standardized mean difference (SMD) or risk ratios with 95% confidence intervals (95% CI). We used absolute risk difference (RD) with 95% CI to report adverse effects.

MAIN RESULTS

We included 15 trials (5540 participants). Tramadol was examined in five trials (1378 participants); it was found to be better than placebo for pain (SMD -0.55, 95% CI -0.66 to -0.44; low quality evidence) and function (SMD -0.18, 95% CI -0.29 to -0.07; moderate quality evidence). Transdermal buprenorphine (two trials, 653 participants) may make little difference for pain (SMD -2.47, 95%CI -2.69 to -2.25; very low quality evidence), but no difference compared to placebo for function (SMD -0.14, 95%CI -0.53 to 0.25; very low quality evidence). Strong opioids (morphine, hydromorphone, oxycodone, oxymorphone, and tapentadol), examined in six trials (1887 participants), were better than placebo for pain (SMD -0.43, 95%CI -0.52 to -0.33; moderate quality evidence) and function (SMD -0.26, 95% CI -0.37 to -0.15; moderate quality evidence). One trial (1583 participants) demonstrated that tramadol may make little difference compared to celecoxib (RR 0.82, 95% CI 0.76 to 0.90; very low quality evidence) for pain relief. Two trials (272 participants) found no difference between opioids and antidepressants for either pain (SMD 0.21, 95% CI -0.03 to 0.45; very low quality evidence), or function (SMD -0.11, 95% -0.63 to 0.42; very low quality evidence). The included trials in this review had high drop-out rates, were of short duration, and had limited interpretability of functional improvement. They did not report any serious adverse effects, risks (addiction or overdose), or complications (sleep apnea, opioid-induced hyperalgesia, hypogonadism). In general, the effect sizes were medium for pain and small for function.

AUTHORS' CONCLUSIONS

There is some evidence (very low to moderate quality) for short-term efficacy (for both pain and function) of opioids to treat CLBP compared to placebo. The very few trials that compared opioids to non-steroidal anti-inflammatory drugs (NSAIDs) or antidepressants did not show any differences regarding pain and function. The initiation of a trial of opioids for long-term management should be done with extreme caution, especially after a comprehensive assessment of potential risks. There are no placebo-RCTs supporting the effectiveness and safety of long-term opioid therapy for treatment of CLBP.