Pharmacologic management of chronic low back pain: synthesis of the evidence

Low-back pain at the emergency department: still not being managed?

Background

Low-back pain (LBP) affects about 40% of people at some point in their lives. In the presence of “red flags”, further tests must be done to rule out underlying problems; however, biomedical imaging is currently overused. LBP involves large in-hospital and out-of-hospital economic costs, and it is also the most common musculoskeletal disorder seen in emergency departments (EDs).

Patients and methods

This retrospective observational study enrolled 1,298 patients admitted to the ED, including all International Classification of Diseases 10 diagnosis codes for sciatica, lumbosciatica, and lumbago. We collected patients’ demographic data, medical history, lab workup and imaging performed at the ED, drugs administered at the ED, ED length of stay (LOS), numeric rating scale pain score, admission to ward, and ward LOS data. Thereafter, we performed a cost analysis.

Results

Mean numeric rating scale scores were higher than 7/10. Home medication consisted of no drug consumption in up to 90% of patients. Oxycodone–naloxone was the strong opioid most frequently prescribed for the home. Once at the ED, nonsteroidal anti-inflammatory drugs and opiates were administered to up to 72% and 42% of patients, respectively. Imaging was performed in up to 56% of patients. Mean ED LOS was 4 hours, 14 minutes. A total of 43 patients were admitted to a ward. The expense for each non-ward-admitted patient was approximately €200 in the ED, while the mean expense for ward-admitted patients was €9,500, with a mean LOS of 15 days.

Conclusion

There is not yet a defined therapeutic care process for the patient with LBP with clear criteria for an ED visit. It is to this end that we need a clinical pathway for the prehospital management of LBP syndrome and consequently for an in-hospital time-saving therapeutic approach to the patient.

Analgecine, the extracts of Vaccinia-inoculated rabbit skin, effectively alleviates the chronic low back pain with little side effect - A randomized multi-center double-blind placebo-controlled phase 3 clinical trial

Background

Chronic low back pain affects daily activities at home and workplaces and causes a huge economic burden. Current therapeutic options are very limited and the effects of available pharmacological agents are less than satisfactory. While NSAIDs might be effective for the short term and opioids might help with urgent pain relief and improving the life quality, their long-term use is associated with significant side effects and drug misuse or abuse. To seek alternative pharmacological agents for effective treatment, we examined the therapeutic potential of the extracts of Vaccinia variola-inoculated rabbit skin (Analgecine, abbreviated as AGC) in patients with chronic low back pain due to degenerative vertebral disorders.

Methods

In this randomized multi-center double-blind placebo-controlled phase 3 clinical trial (Chinese Clinical Trial Registry number 2009L01498), we enrolled patients (aged 26-70 years) with chronic low back pain for at least 3 months due to degenerative spinal (vertebral) disorders from 7 medical centers in China, and randomly allocated 459 participants to receive oral AGC or placebo for 28 days to study the efficacy and safety of AGC. Randomization was performed according to a centralized randomization schedule, which was blocked by study sites and generated by an unmasked statistician independent of study conduct and data analysis. Both participants and staff at each study site were masked to treatment assignment. The primary efficacy endpoint was the change of the mean pain intensity, based on an 11-point numerical rating scale, between the baseline and the last week of treatment, with the primary efficacy analysis of intention to treat. The ratio between exposed and unexposed groups was designed to be 3:1 in order to increase the likelihood of demonstrating the AGC effect upon repeated measures.

Results

347 patients were assigned to receive AGC (4 units/tablet; 2 tablets twice a day) and 112 patients were to take placebo. Among them, 324 patients taking AGC and 112 receiving placebo completed the assessment. Patients receiving AGC reported significant pain relief at the end of week 2 and 3 compared to those taking placebo, with mean reduction of the pain scores as 1.7 vs. 0.9 at week 2 (p < 0.0001) and 2.8 vs. 1.2 at week 3 (p < 0.0001). A total of 47 AGC-treated patients reported 85 treatment emergent adverse events while 16 patients taking placebo reported 26 events, but no serious side effects were found to be related to AGC treatment.

Conclusion

Analgecine (AGC, 8 units twice daily) effectively alleviates chronic low back pain due to degenerative vertebral disorders when compared to placebo and is well tolerated by tested individuals, and can be considered as a first-line treatment for chronic low pain due to degenerative vertebral diseases.

An update on the management of chronic lumbar discogenic pain

Lumbar degenerative disc disease without disc herniation, also known as discogenic pain, is an elusive diagnosis of chronic low back pain. Lumbar provocation discography and fusion surgery have been frequently utilized for several decades as the gold standards for the diagnosis and treatment of symptomatic lumbar discogenic pain, though controversial, based on conjecture, rather than evidence. In addition to lumbar fusion, various other operative and nonoperative modalities of treatments are available in managing chronic lumbar discogenic pain. This review provides an updated assessment of the management of chronic lumbar discogenic pain with a critical look at the many modalities of treatments that are currently available.

Treatment of discogenic back pain with autologous bone marrow concentrate injection with minimum two year follow-up

PURPOSE

The purpose of this study is to assess safety and feasibility of intradiscal bone marrow concentrate (BMC) injections to treat discogenic pain as an alternative to surgery.

METHODS

A total of 26 patients (11 male, 15 female, aged 18-61 years, 13 single level, 13 two level) that met inclusion criteria of chronic (> 6 months) discogenic low back pain, degenerative disc pathology assessed by magnetic resonance imaging (MRI) with modified Pfirrmann grade of IV-VII at one or two levels, candidate for surgical intervention (failed conservative treatment and radiologic findings) and a visual analogue scale (VAS) pain score of 40 mm or more at initial visit. Initial Oswestry Disability Index (ODI) and VAS pain score average was 56.5 % and 80.1 mm (0-100), respectively. Adverse event reporting, ODI score, VAS pain score, MRI radiographic changes, progression to surgery and cellular analysis of BMC were noted. Retrospective cell analysis by flow cytometry and colony forming unit-fibroblast (CFU-F) assays were performed to characterise each patient's BMC and compare with clinical outcomes. The BMC was injected into the nucleus pulposus of the symptomatic disc(s) under fluoroscopic guidance. Patients were evaluated clinically prior to treatment and at three, six, 12 and 24 months and radiographically prior to treatment and at 12 months.

RESULTS

There were no complications from the percutaneous bone marrow aspiration or disc injection. Of 26 patients, 24 (92 %) avoided surgery through 12 months, while 21 (81 %) avoided surgery through two years. Of the 21 surviving patients, the average ODI and VAS scores were reduced to 19.9 and 27.0 at three months and sustained to 18.3 and 22.9 at 24 months, respectively (p ≤ 0.001). Twenty patients had follow-up MRI at 12 months, of whom eight had improved by at least one Pfirrmann grade, while none of the discs worsened. Total and rate of pain reduction were linked to mesenchymal stem cell concentration through 12 months. Only five of the 26 patients elected to undergo surgical intervention (fusion or artificial disc replacement) by the two year milestone.

CONCLUSIONS

This study provides evidence of safety and feasibility in the non-surgical treatment of discogenic pain with autologous BMC, with durable pain relief (71 % VAS reduction) and ODI improvements (> 64 %) through two years.

The Effect of Motivational Interviewing on Prescription Opioid Adherence Among Older Adults With Chronic Pain

PURPOSE

To test the effect of office-based motivational interviewing (MI) on prescription opioid adherence in older adults with chronic pain.

DESIGN AND METHODS

Pre- and post-design was used. Thirty chronic pain patients participated in a 4-week MI in two outpatient settings.

FINDINGS

Participants demonstrated a significantly reduced risk of prescription opioid misuse, decreased substance use, increased self-efficacy, increased motivation to change, and decreased depression at both the post-test and 1-month follow-up.

PRACTICE IMPLICATION

MI can be effectively delivered in outpatient settings for older adults who are at risk for opioid misuse. Clinicians could incorporate MI techniques to enhance prescription opioid adherence.

HTLV-1-associated myelopathy/tropical spastic paraparesis

Human T-lymphotropic virus 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a progressive disease of the CNS that causes weakness or paralysis of the legs, lower back pain and urinary symptoms. HAM/TSP was first described in Jamaica in the nineteenth century, but the aetiology of the condition, infection with the retrovirus HTLV-1, was only identified in the 1980s. HAM/TSP causes chronic disability and, accordingly, imposes a substantial health burden in areas where HTLV-1 infection is endemic. Since the discovery of the cause of HAM/TSP, considerable advances have been made in the understanding of the virology, immunology, cell biology and pathology of HTLV-1 infection and its associated diseases. However, progress has been limited by the lack of accurate animal models of the disease. Moreover, the treatment of HAM/TSP remains highly unsatisfactory: antiretroviral drugs have little impact on the infection and, although potential disease-modifying therapies are widely used, their value is unproved. At present, clinical management is focused on symptomatic treatment and counselling. Here, we summarize current knowledge on the epidemiology, pathogenesis and treatment of HAM/TSP and identify areas in which further research is needed. For an illustrated summary of this Primer, visit: http://go.nature.com/tjZCFM.

Clinical management of radicular pain

This review provides an overview of the diagnosis and treatment strategies for the management of radicular pain. While it is not as common as axial spinal pain, radicular pain combines the advantage of leveraging appropriate diagnostic strategies and definitive treatments with well-informed outcome measures. Multiple diagnostic measures include not only history and physical examination, but also imaging. The treatment modalities include pharmacologic management, physical and rehabilitation measures, interventional techniques and surgical treatments. Here, the authors describe the prevalence and pathophysiology of radicular pain, risk factors, diagnostic strategies, treatment modalities and the evidence for these management strategies. Finally, the authors show the efficacy of conservative management, despite surgical management being the gold standard.

Are Physicians Safely Prescribing Opioids for Chronic Noncancer Pain? A Systematic Review of Current Evidence

BACKGROUND

With rising prescription of opioid medications for chronic noncancer pain (CNCP) in the past years, opioid abuse and overdose deaths have increased in parallel. To ensure adequate treatment outcomes and reduce the risks linked with the chronic use of opioids, practitioner's adherence to treatment guidelines is essential. This study summarizes published recommendations about the strategies to reduce the risks associated with the chronic use of opioids and evaluates the adherence of physicians to these recommendations.

METHOD

A systematic literature search was undertaken in May 2014 using major databases. Studies were included if they examined the adherence of practitioners with at least one form of opioid risk reduction strategy. Benchmark guidelines cited in these studies were also reviewed.

RESULTS

The search yielded 683 records, 14 of which were found to evaluate adherence of physicians to opioid risk reduction strategies. Nine benchmark guidelines were found. Almost all physicians consider opioid therapy only when other safer approaches have failed and do not prescribe opioids at doses greater than 200 mg/day of morphine equivalent. Unfortunately, less than 50% assess pain intensity using a pain scale; they often consider transdermal fentanyl safe for opioid-naïve patients and fail to discontinue opioids if they were ineffective in relieving patients' pain.

CONCLUSIONS

Substantial practice and knowledge gaps were identified, including the use of pain scales and prescription of transdermal fentanyl in opioid-naïve patients, which have important implications for patient's safety. Guidelines more practical to physicians' settings and further education of physicians are warranted.

Epidemiology, diagnosis, and treatment of neck pain

Neck pain is the fourth leading cause of disability, with an annual prevalence rate exceeding 30%. Most episodes of acute neck pain will resolve with or without treatment, but nearly 50% of individuals will continue to experience some degree of pain or frequent occurrences. History and physical examination can provide important clues as to whether the pain is neuropathic or mechanical and can also be used to identify "red flags" that may signify serious pathology, such as myelopathy, atlantoaxial subluxation, and metastases. Magnetic resonance imaging is characterized by a high prevalence of abnormal findings in asymptomatic individuals but should be considered for cases involving focal neurologic symptoms, pain refractory to conventional treatment, and when referring a patient for interventional treatment. Few clinical trials have evaluated treatments for neck pain. Exercise treatment appears to be beneficial in patients with neck pain. There is some evidence to support muscle relaxants in acute neck pain associated with muscle spasm, conflicting evidence for epidural corticosteroid injections for radiculopathy, and weak positive evidence for cervical facet joint radiofrequency denervation. In patients with radiculopathy or myelopathy, surgery appears to be more effective than nonsurgical therapy in the short term but not in the long term for most people.

Mesenchymal stem cell tracking in the intervertebral disc

Low back pain is a common clinical problem, which leads to significant social, economic and public health costs. Intervertebral disc (IVD) degeneration is accepted as a common cause of low back pain. Initially, this is characterized by a loss of proteoglycans from the nucleus pulposus resulting in loss of tissue hydration and hydrostatic pressure. Conservative management, including analgesia and physiotherapy often fails and surgical treatment, such as spinal fusion, is required. Stem cells offer an exciting possible regenerative approach to IVD disease. Preclinical research has demonstrated promising biochemical, histological and radiological results in restoring degenerate IVDs. Cell tracking provides an opportunity to develop an in-depth understanding of stem cell survival, differentiation and migration, enabling optimization of stem cell treatment. Magnetic Resonance Imaging (MRI) is a non-invasive, non-ionizing imaging modality with high spatial resolution, ideally suited for stem cell tracking. Furthermore, novel MRI sequences have the potential to quantitatively assess IVD disease, providing an improved method to review response to biological treatment. Superparamagnetic iron oxide nanoparticles have been extensively researched for the purpose of cell tracking. These particles are biocompatible, non-toxic and act as excellent MRI contrast agents. This review will explore recent advances and issues in stem cell tracking and molecular imaging in relation to the IVD.

Antinociceptive properties of physalins from Physalis angulata

Pain is the most common reason a patient sees a physician. Nevertheless, the use of typical painkillers is not completely effective in controlling all pain syndromes; therefore further attempts have been made to develop improved analgesic drugs. The present study was undertaken to evaluate the antinociceptive properties of physalins B (1), D (2), F (3), and G (4) isolated from Physalis angulata in inflammatory and centrally mediated pain tests in mice. Systemic pretreatment with 1-4 produced dose-related antinociceptive effects on the writhing and formalin tests, traditional screening tools for the assessment of analgesic drugs. On the other hand, only 3 inhibited inflammatory parameters such as hyperalgesia, edema, and local production of TNF-α following induction with complete Freund's adjuvant. Treatment with 1, 3, and 4 produced an antinociceptive effect on the tail flick test, suggesting a centrally mediated antinociception. Reinforcing this idea, 2-4 enhanced the mice latency reaction time during the hot plate test. Mice treated with physalins did not demonstrate motor performance alterations. These results suggest that 1-4 present antinociceptive properties associated with central, but not anti-inflammatory, events and indicate a new pharmacological property of physalins.

Involvement of nitridergic and opioidergic pathways in the antinociception of gabapentin in the orofacial formalin test in mice

BACKGROUND

Pain is one of the most common problems in clinical medicine. There is considerable evidence that pharmacologic approaches are the most widely used therapeutic options to ameliorate persistent or chronic pain. In this study it was evaluated the effect of l-NAME and naltrexone in the antinociception induced by administration of gabapentin in the orofacial formalin test of mice.

METHODS

The algesiometer assay was performed by the administration of 20 μl of 2% formalin solution injected into the upper right lip of each mouse.

RESULTS

The dose of gabapentin that produces the 50% of the maximum possible effect (ED50) was significantly increased by the pretreatment with l-NAME or naltrexone.

CONCLUSIONS

These results suggest that gabapentin produce antinociception partly via the activation nitridergic pathways and opioid system.

Advice from professional societies: appropriate use of NSAIDs

OBJECTIVE

Non-steroidal anti-inflammatory drugs (NSAIDs) are some of the most commonly used medications due to their well-known analgesic, anti-inflammatory, and antipyretic actions. Due to their known benefits and inherent risks, there have been multiple guidelines from national professional societies that suggest appropriate use to provide both maximum benefit and mitigate risk of adverse events, particularly in older individuals.

DESIGN

A literature search was undertaken using PubMed and search terms including pain, aging, treatment, non-steroidal anti-inflammatory drugs, arthritis, older patient, and guidelines. Practice guideline reviews were conducted from the following sources: American Geriatric Society, American College of Rheumatology, and the European League Against Rheumatism suggesting the appropriate and safer use of NSAIDs, along with references to guidelines product by Osteoarthritis Research International, the American Gastroenterological Association.

CONCLUSIONS

Literature-based and professional society guidelines provides clinicians with means optimize efficacy and safety of NSAIDs in clinical practice. Summary recommendations are provided in this review.

Chronic pain treatment with opioid analgesics: benefits versus harms of long-term therapy

Chronic non-cancer pain (CNCP) is a disabling chronic condition with a high prevalence rate around the world. Opioids are routinely prescribed for treatment of chronic pain (CP). In the past two decades there has been a massive increase in the number of opioid prescriptions, prescribed daily opioid doses and overall opioid availability. Many more patients with CNCP receive high doses of long-acting opioids on a long-term basis. Yet CP and related disability rates remain high, and majority of the patients with CNCP are dissatisfied with their treatments. Intersecting with the upward trajectory in opioid use are the increasing trends in opioid related adverse effects, especially prescription drug abuse, addiction and overdose deaths. This complex situation raises questions on the relevance of opioid therapy in the treatment of CNCP. This article reviews current evidence on opioid effectiveness, the benefits and harms of long-term therapy in CNCP.

Epidural steroids: a comprehensive, evidence-based review

Epidural steroid injections (ESIs) are the most widely utilized pain management procedure in the world, their use supported by more than 45 placebo-controlled studies and dozens of systematic reviews. Despite the extensive literature on the subject, there continues to be considerable controversy surrounding their safety and efficacy. The results of clinical trials and review articles are heavily influenced by specialty, with those done by interventional pain physicians more likely to yield positive findings. Overall, more than half of controlled studies have demonstrated positive findings, suggesting a modest effect size lasting less than 3 months in well-selected individuals. Transforaminal injections are more likely to yield positive results than interlaminar or caudal injections, and subgroup analyses indicate a slightly greater likelihood for a positive response for lumbar herniated disk, compared with spinal stenosis or axial spinal pain. Other factors that may increase the likelihood of a positive outcome in clinical trials include the use of a nonepidural (eg, intramuscular) control group, higher volumes in the treatment group, and the use of depo-steroid. Serious complications are rare following ESIs, provided proper precautions are taken. Although there are no clinical trials comparing different numbers of injections, guidelines suggest that the number of injections should be tailored to individual response, rather than a set series. Most subgroup analyses of controlled studies show no difference in surgical rates between ESI and control patients; however, randomized studies conducted by spine surgeons, in surgically amenable patients with standardized operative criteria, indicate that in some patients the strategic use of ESI may prevent surgery.

Pharmacological Interventions Including Medical Injections for Neck Pain: An Overview as Part of the ICON Project

OBJECTIVES

To conduct an overview (review-of-reviews) on pharmacological interventions for neck pain.

SEARCH STRATEGY

Computerized databases and grey literature were searched from 2006 to 2012.

SELECTION CRITERIA

Systematic reviews of randomized controlled trials (RCT) in adults with acute to chronic neck pain reporting effects of pharmacological interventions including injections on pain, function/disability, global perceived effect, quality of life and patient satisfaction.

DATA COLLECTION & ANALYSIS

Two independent authors selected articles, assessed risk of bias and extracted data The GRADE tool was used to evaluate the body of evidence and an external panel provided critical review.

MAIN RESULTS

We found 26 reviews reporting on 47 RCTs. Most pharmacological interventions had low to very low quality methodologic evidence with three exceptions. For chronic neck pain, there was evidence of: a small immediate benefit for eperison hydrochloride (moderate GRADE, 1 trial, 157 participants);no short-term pain relieving benefit for botulinum toxin-A compared to saline (strong GRADE; 5 trial meta-analysis, 258 participants) nor for subacute/chronic whiplash (moderate GRADE; 4 trial meta-analysis, 183 participants) including reduced pain, disability or global perceived effect; andno long-term benefit for medial branch block of facet joints with steroids (moderate GRADE; 1 trial, 120 participants) over placebo to reduce pain or disability;

REVIEWERS' CONCLUSIONS

While in general there is a lack of evidence for most pharmacological interventions, current evidence is against botulinum toxin-A for chronic neck pain or subacute/chronic whiplash; against medial branch block with steroids for chronic facet joint pain; but in favour of the muscle relaxant eperison hydrochloride for chronic neck pain.

Buprenorphine transdermal system and quality of life in opioid-experienced patients with chronic low back pain

OBJECTIVES

To evaluate the impact of 12 weeks of treatment with Butrans® (buprenorphine) transdermal system (BTDS) on the health-related quality of life (HRQoL) for patients with chronic low back pain (CLBP), and the maintenance of effects over 52 weeks.

RESEARCH DESIGN AND METHODS

A multicenter, enriched, double-blind (DB), randomized trial comparing BTDS 20 μg/h (BTDS 20) against 5 μg/h (BTDS 5) for treatment of opioid-experienced patients with moderate-to-severe CLBP, including a 52-week open-label (OL) extension phase.

MAIN OUTCOME MEASURES

QoL was measured with the SF-36v2 survey before and after an OL run-in period with BTDS 20, three times during the DB phase, and seven times over the extension phase. This post hoc analysis tested for SF-36v2 score differences between treatment groups during the DB phase and maintenance of effects over the extension phase.

RESULTS

At 12 weeks, BTDS 20 produced larger improvements than BTDS 5 in role limitations due to physical health, bodily pain and overall physical QoL (p < 0.01). Treatment group differences in overall physical QoL were sustained throughout the DB phase. Quality-of-life improvements associated with BTDS 20 persisted through the extension phase.

CONCLUSIONS

These data suggest that opioid-experienced moderate-to-severe CLBP patients receiving BTDS 20 exhibited better QoL than patients receiving BTDS 5.

The outcomes of manipulation or mobilization therapy compared with physical therapy or exercise for neck pain: a systematic review

Study Design Systematic review. Study Rationale Neck pain is a prevalent condition. Spinal manipulation and mobilization procedures are becoming an accepted treatment for neck pain. However, data on the effectiveness of these treatments have not been summarized. Objective To compare manipulation or mobilization of the cervical spine to physical therapy or exercise for symptom improvement in patients with neck pain. Methods A systematic review of the literature was performed using PubMed, the National Guideline Clearinghouse Database, and bibliographies of key articles, which compared spinal manipulation or mobilization therapy with physical therapy or exercise in patients with neck pain. Articles were included based on predetermined criteria and were appraised using a predefined quality rating scheme. Results From 197 citations, 7 articles met all inclusion and exclusion criteria. There were no differences in pain improvement when comparing spinal manipulation to exercise, and there were inconsistent reports of pain improvement in subjects who underwent mobilization therapy versus physical therapy. No disability improvement was reported between treatment groups in studies of acute or chronic neck pain patients. No functional improvement was found with manipulation therapy compared with exercise treatment or mobilization therapy compared with physical therapy groups in patients with acute pain. In chronic neck pain subjects who underwent spinal manipulation therapy compared to exercise treatment, results for short-term functional improvement were inconsistent. Conclusion The data available suggest that there are minimal short- and long-term treatment differences in pain, disability, patient-rated treatment improvement, treatment satisfaction, health status, or functional improvement when comparing manipulation or mobilization therapy to physical therapy or exercise in patients with neck pain. This systematic review is limited by the variability of treatment interventions and lack of standardized outcomes to assess treatment benefit.

Opioid use among low back pain patients in primary care: Is opioid prescription associated with disability at 6-month follow-up?

Opioid prescribing for chronic noncancer pain is increasing, but there is limited knowledge about longer-term outcomes of people receiving opioids for conditions such as back pain. This study aimed to explore the relationship between prescribed opioids and disability among patients consulting in primary care with back pain. A total of 715 participants from a prospective cohort study, who gave consent for review of medical and prescribing records and completed baseline and 6 month follow-up questionnaires, were included. Opioid prescription data were obtained from electronic prescribing records, and morphine equivalent doses were calculated. The primary outcome was disability (Roland-Morris Disability Questionnaire [RMDQ]) at 6 months. Multivariable linear regression was used to examine the association between opioid prescription at baseline and RMDQ score at 6 months. Analyses were adjusted for potential confounders using propensity scores reflecting the probability of opioid prescription given baseline characteristics. In the baseline period, 234 participants (32.7%) were prescribed opioids. In the final multivariable analysis, opioid prescription at baseline was significantly associated with higher disability at 6-month follow-up (P < .022), but the magnitude of this effect was small, with a mean RMDQ score of 1.18 (95% confidence interval: 0.17 to 2.19) points higher among those prescribed opioids compared to those who were not. Our findings indicate that even after adjusting for a substantial number of potential confounders, opioids were associated with slightly worse functioning in back pain patients at 6-month follow-up. Further research may help us to understand the mechanisms underlying these findings and inform clinical decisions regarding the usefulness of opioids for back pain.

The hidden effects of blinded, placebo-controlled randomized trials: an experimental investigation

The knowledge of having only a 50% chance of receiving an active drug can result in reduced efficacy in blinded randomized clinical trials (RCTs) compared to clinical practice (reduced external validity). Moreover, minor onset sensations associated with the drug (but not with an inert placebo) can further challenge the attribution of group differences to drug-specific efficacy (internal validity). We used a randomized experimental study with inert placebos (inert substance) vs active placebos (inducing minor sensations), and different instructions about group allocation (probability of receiving drug: 0%, 50%, 100%). One hundred forty-four healthy volunteers were informed that a new application method for a well-known painkiller would be tested. Pain thresholds were assessed before and after receiving nasal spray. Half of the nasal sprays were inert placebos (sesame oil), while the other half were active placebos inducing prickling nasal sensations (sesame oil with 0.014% capsaicin). The major outcome was pain threshold after placebo application. A substantial expectation effect was found for the inert placebo condition, with participants who believed they had received an active drug reporting the highest pain thresholds. Active placebos show substantial differences to passive placebos in the 50% chance group. Therefore, patient expectations are significantly different in placebo-controlled clinical trials (50% chance) vs clinical practice (100% chance). Moreover, minor drug onset sensations can challenge internal validity. Effect sizes for these mechanisms are medium, and can substantially compete with specific drug effects. For clinical trials, new study designs are needed that better control for these effects.

Impact of homologous and non-homologous recombination in the genomic evolution of Escherichia coli

Background

Escherichia coli is an important species of bacteria that can live as a harmless inhabitant of the guts of many animals, as a pathogen causing life-threatening conditions or freely in the non-host environment. This diversity of lifestyles has made it a particular focus of interest for studies of genetic variation, mainly with the aim to understand how a commensal can become a deadly pathogen. Many whole genomes of E. coli have been fully sequenced in the past few years, which offer helpful data to help understand how this important species evolved.

Results

We compared 27 whole genomes encompassing four phylogroups of Escherichia coli (A, B1, B2 and E). From the core-genome we established the clonal relationships between the isolates as well as the role played by homologous recombination during their evolution from a common ancestor. We found strong evidence for sexual isolation between three lineages (A+B1, B2, E), which could be explained by the ecological structuring of E. coli and may represent on-going speciation. We identified three hotspots of homologous recombination, one of which had not been previously described and contains the aroC gene, involved in the essential shikimate metabolic pathway. We also described the role played by non-homologous recombination in the pan-genome, and showed that this process was highly heterogeneous. Our analyses revealed in particular that the genomes of three enterohaemorrhagic (EHEC) strains within phylogroup B1 have converged from originally separate backgrounds as a result of both homologous and non-homologous recombination.

Conclusions

Recombination is an important force shaping the genomic evolution and diversification of E. coli, both by replacing fragments of genes with an homologous sequence and also by introducing new genes. In this study, several non-random patterns of these events were identified which correlated with important changes in the lifestyle of the bacteria, and therefore provide additional evidence to explain the relationship between genomic variation and ecological adaptation.

Antineuropathic and antinociceptive drugs combination in patients with chronic low back pain: a systematic review

Purpose. Chronic low back pain (LBP) is often characterized by both nociceptive and neuropathic components. While various monotherapies have been reported of only limited efficacy, combining drugs with different mechanisms of action and targets appears a rational approach. Aim of this systematic review is to assess the efficacy and safety of different combined pharmacological treatments, compared to monotherapy or placebo, for the pharmacological treatment of chronic LBP. Methods. Published papers, written or abstracted in English from 1990 through 2011, comparing combined pharmacological treatments of chronic LBP to monotherapy or placebo were reviewed. Results. Six articles met the inclusion criteria. Pregabalin combined with celecoxib or opioids was shown to be more effective than either monotherapy. Oxycodone-paracetamol versus previous treatments and tramadol-paracetamol versus placebo were also reported as effective, while morphine-nortriptyline did not show any benefit over any single agent. Conclusions. In spite of theoretical advantages of combined pharmacological treatments of chronic LBP, clinical studies are remarkably few. Available data show that combined therapy, including antinociceptive and antineuropathic agents is more effective than monotherapy, with similar side effects.

Morphine and clonidine synergize to ameliorate low back pain in mice

Chronic low back pain (LBP) is a debilitating condition associated with signs of axial and radiating pain. In humans with chronic LBP, opioids are often prescribed with varying outcomes and a multitude of side effects. Combination therapies, in which multiple pharmacological agents synergize to ameliorate pain without similar potentiation of adverse reactions, may be useful in improving therapeutic outcome in these patients. The SPARC-null mouse model of low back pain due to disc degeneration was used to assess the effects of opioid (morphine) and α₂-adrenergic agonist (clonidine) coadministration on measures of axial and radiating pain. The results indicate that systemic morphine and clonidine, coadministered at a fixed dose of 100 : 1 (morphine : clonidine), show a synergistic interaction in reversing signs of axial LBP, in addition to improving the therapeutic window for radiating LBP. Furthermore, these improvements were observed in the absence of synergy in assays of motor function which are indicative of side effects such as sedation and motor incoordination. These data show that the addition of low-dose systemic clonidine improves therapeutic outcome in measures of both axial and radiating pain. Combination therapy could be of enormous benefit to patients suffering from chronic LBP.

Chronic low back pain: a heterogeneous condition with challenges for an evidence-based approach

"Chronic" low back pain (LBP), defined as present for 3 or more months, has become a major socioeconomic problem insufficiently addressed by five major entities largely working in isolation from one another - procedural based specialties, strength based rehabilitation, cognitive behavioral therapy, pain management and manipulative care. As direct and indirect costs continue to rise, many authors have systematically evaluated the body of evidence in an effort to demonstrate the effectiveness (or lack thereof) for various diagnostic and therapeutic interventions. The objective of this Spine Focus issue is not to replicate previous work in this area. Rather, our expert panel has chosen a set of potentially controversial topics for more in-depth study and discussion. A recurring theme is that chronic LBP is a heterogeneous condition, and this affects the way it is diagnosed, classified, treated, and studied. The efficacy of some treatments may be appreciated only through a better understanding of heterogeneity of treatment effects (i.e., identification of clinically relevant subgroups with differing responses to the same treatment). Current clinical guidelines and payer policies for LBP are systematically compared for consistency and quality. Novel approaches for data gathering, such as national spine registries, may offer a preferable approach to gain meaningful data and direct us towards a "results-based medicine." This approach would require more high-quality studies, more consistent recording for various phenotypes and exploration of studies on genetic epidemiologic undertones to guide us in the emerging era of "results based medicine."