Immunomodulatory effects of pharmaceutical opioids and antipyretic analgesics: Mechanisms and relevance to infection

Understanding how pharmaceutical opioids and antipyretic analgesics interact with the immune system potentially has major clinical implications for management of patients with infectious diseases and surgical and critical care patients. An electronic search was carried out on MEDLINE, EMBASE, PsycINFO, CENTRAL and the Cochrane library to identify reports describing the immunomodulatory effects of opioid analgesics and antipyretic analgesics, and their effects in infectious diseases. In adaptive immunity, nonsteroidal anti-inflammatory drugs have divergent effects: augmenting cell-mediated immunity but inhibiting humoral immunity. Nonsteroidal anti-inflammatory drugs have demonstrated a beneficial role in Mycobacterium tuberculosis infection and histoplasmosis in animals, and may be plausible adjuvants to antimicrobial agents in these diseases. There is a need to evaluate these findings rigorously in human clinical trials. There is preliminary evidence demonstrating antiviral effects of indomethacin in SARS CoV-2 in vitro; however, uncertainty regarding its clinical benefit in humans needs to be resolved in large clinical trials. Certain opioid analgesics are associated with immunosuppressive effects, with a developing understanding that fentanyl, morphine, methadone and buprenorphine suppress innate immunity, whilst having diverse effects on adaptive immunity. Morphine suppresses key cells of the innate immunity and is associated with greater risk of infection in the postsurgical setting. Efforts are needed to achieve adequate analgesia whilst avoiding suppression of the innate immunity in the immediate postoperative period caused by certain opioids, particularly in cancer surgery.

Advice and education provide small short-term improvements in pain and disability in people with non-specific spinal pain: a systematic review

QUESTIONS

What is the effect of advice/education compared with placebo or no advice/education on pain and disability in people with non-specific spinal pain? To what extent do characteristics of the patients, trial or intervention modify the estimate of the treatment effects?

DESIGN

A systematic review with meta-analyses of randomised controlled trials.

PARTICIPANTS

Adults with non-specific back and/or neck pain with or without radiating leg/arm pain of any duration were included. Trials recruiting pregnant women or surgical patients in the immediate postoperative phase were ineligible.

INTERVENTION

Advice or education.

OUTCOME MEASURES

The primary outcomes were self-reported pain and disability, and the secondary outcome was adverse events. The following potential effect modifiers were examined: risk of bias, duration of pain, location of pain, intensity of intervention and mode of intervention.

RESULTS

Twenty-seven trials involving 7,006 participants were included. Eighteen of the included trials were assessed as being at low risk of bias (≥ 6 on the PEDro scale). There was low-quality evidence that advice had a small effect on pain (MD -8.2, 95% CI -12.5 to -3.9, n = 2,241) and moderate-quality evidence that advice had a small effect on disability (MD -4.5, 95% CI -7.9 to -1.0, n = 2,579) compared with no advice or placebo advice in the short-term. None of the items that were assessed modified the treatment effects.

CONCLUSION

Advice provides short-term improvements in pain and disability in non-specific spinal pain, but the effects are small and may be insufficient as the sole treatment for patients with spinal pain.

REGISTRATION

PROSPERO CRD42020162008.

Systematic review with meta-analysis: The effects of non-steroidal anti-inflammatory drugs and anti-platelet therapy on the incidence and recurrence of hepatocellular carcinoma

BACKGROUND

Chemoprevention with NSAIDs, including aspirin, and anti-platelet therapy (APT), has been suggested to reduce the incidence and recurrence of hepatocellular carcinoma (HCC).

AIM

To determine by meta-analysis whether NSAIDs and APT use affected HCC incidence, HCC recurrence and liver-related mortality in at-risk populations with chronic liver disease.

METHOD

Electronic databases including Pubmed, Scopus, Medline, Embase and Cochrane Library were searched (from inception to 31 May 2021) for eligible studies evaluating the impacts of NSAID or APT use on HCC incidence, recurrence and mortality. Data on HCC incidence, recurrence, liver-related mortality or bleeding complications had to be available. Studies were included if they evaluated adults with hepatitis B virus (HBV), hepatitis C virus (HCV), alcohol-related liver disease (ALD) or nonalcoholic steatohepatitis that were administered at least one NSAID or APT for a defined period of time and were followed for at least 6 months. The primary outcome was HCC incidence. Secondary outcomes included: HCC recurrence, liver-related mortality and bleeding complications. Data were pooled using a random effects model with hazard ratios (HRs) or odds ratio (OR), and 95% confidence intervals (CIs) presented.

RESULTS

Of 3773 articles screened, 19 studies were included, with a total of 147 283 participants. Aspirin use reduced the risk of HCC incidence (HR: 0.51, 95% CI: 0.36-0.72); and improved liver-related mortality (OR: 0.32, 95% CI: 0.15-0.70), with a small increased risk of gastrointestinal bleeding events (OR: 1.32, 95% CI: 1.08-1.94). With respect to HCC recurrence following treatment, analysis of all aspirin and NSAID treatment (including; aspirin only; non-aspirin NSAIDs only; and combination NSAIDs groups) was associated with a decreased risk of HCC recurrence (HR: 0.80, 95% CI: 0.75-0.86). By stratified analysis, only the non-aspirin NSAID group showed significant risk reduction (HR: 0.73, 95% CI: 0.63-0.84).

CONCLUSION

The study supports the use of aspirin in at-risk individuals to reduce the incidence of HCC and liver-related mortality. HCC recurrence following treatment was lower with NSAID treatment.

The efficacy and safety of paracetamol for pain relief: an overview of systematic reviews

OBJECTIVE

To evaluate the efficacy and safety of paracetamol as an analgesic medication in a range of painful conditions.

STUDY DESIGN

Systematic review of systematic reviews of the analgesic effects of paracetamol in randomised, placebo-controlled trials. Conduct of systematic reviews was assessed with AMSTAR-2; confidence in effect estimates (quality of evidence) was assessed with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria.

DATA SOURCES

MEDLINE, EMBASE, PsycINFO, Cochrane Database of Systematic Reviews; systematic reviews published 1 January 2010 - 30 April 2020.

DATA SYNTHESIS

We extracted pain and adverse events outcomes from 36 systematic reviews that assessed the efficacy of paracetamol in 44 painful conditions. Continuous pain outcomes were expressed as mean differences (MDs; standardised 0-10-point scale); dichotomous outcomes were expressed as risk ratios (RRs). There is high quality evidence that paracetamol provides modest pain relief for people with knee or hip osteoarthritis (MD, -0.3 points; 95% CI, -0.6 to -0.1 points) and after craniotomy (MD, -0.8 points; 95% CI, -1.4 to -0.2 points); there is moderate quality evidence for its efficacy in tension-type headache (pain-free at 2 hours: RR, 1.3; 95% CI, 1.1-1.4) and perineal pain soon after childbirth (patients experiencing 50% pain relief: RR, 2.4; 95% CI, 1.5-3.8). There is high quality evidence that paracetamol is not effective for relieving acute low back pain (MD, 0.2 points; 95% CI, -0.1 to 0.4 points). Evidence regarding efficacy in other conditions was of low or very low quality. Frequency of adverse events was generally similar for people receiving placebo or paracetamol, except that transient elevation of blood liver enzyme levels was more frequent during repeated administration of paracetamol to patients with spinal pain (RR, 3.8; 95% CI, 1.9-7.4).

CONCLUSIONS

For most conditions, evidence regarding the effectiveness of paracetamol is insufficient for drawing firm conclusions. Evidence for its efficacy in four conditions was moderate to strong, and there is strong evidence that paracetamol is not effective for reducing acute low back pain. Investigations that evaluate more typical dosing regimens are required.

PROSPERO REGISTRATION

CRD42015029282 (prospective).

OASIS-a randomised, placebo-controlled trial of oral glucocorticoids for leg pain in patients with acute sciatica: trial protocol

INTRODUCTION

Sciatica is a lower spine condition characterised by radiating leg pain below the knee. It may be accompanied by motor and sensory loss in the distribution of a spinal nerve. There are few effective treatments for sciatica. Orally administered glucocorticoids have shown some promise, however, any beneficial effects need to be confirmed and weighed against drug safety and cost-effectiveness, in a high-quality, definitive trial.

METHODS AND ANALYSIS

The Oral Steroids In Sciatica (OASIS) trial is a randomised, placebo-controlled, double-blind trial that will evaluate a tapering regimen of oral prednisolone in 200 participants with acute sciatica. Participants will be recruited on presentation to general practice, specialist outpatient clinics or hospital emergency departments and randomised to receive orally administered prednisolone 50 mg per day, up to 3 days then tapering to cessation over 10 days, or placebo, for a maximum of 13 days, in addition to guideline advice. Participants will be followed for 1 year. The primary endpoint will be leg pain intensity at 2 weeks. Secondary outcomes will include back pain intensity, disability, time to recovery, quality of life and treatment success rate. Adverse events will be assessed and a cost-effectiveness analysis will be conducted.

ETHICS AND DISSEMINATION

Ethical approval has been granted from the Human Research Ethics Committee, The University of Sydney. Trial results will be disseminated by publications and conference presentations and via the media.

TRIAL REGISTRATION NUMBER

ACTRN12619001716156.

An Electronic Clinical Decision Support System for the Management of Low Back Pain in Community Pharmacy: Development and Mixed Methods Feasibility Study

Background

People with low back pain (LBP) in the community often do not receive evidence-based advice and management. Community pharmacists can play an important role in supporting people with LBP as pharmacists are easily accessible to provide first-line care. However, previous research suggests that pharmacists may not consistently deliver advice that is concordant with guideline recommendations and may demonstrate difficulty determining which patients require prompt medical review. A clinical decision support system (CDSS) may enhance first-line care of LBP, but none exists to support the community pharmacist–client consultation.

Objective

This study aimed to develop a CDSS to guide first-line care of LBP in the community pharmacy setting and to evaluate the pharmacist-reported usability and acceptance of the prototype system.

Methods

A cross-platform Web app for the Apple iPad was developed in conjunction with academic and clinical experts using an iterative user-centered design process during interface design, clinical reasoning, program development, and evaluation. The CDSS was evaluated via one-to-one user-testing with 5 community pharmacists (5 case vignettes each). Data were collected via video recording, screen capture, survey instrument (system usability scale), and direct observation.

Results

Pharmacists’ agreement with CDSS-generated self-care recommendations was 90% (18/20), with medicines recommendations was 100% (25/25), and with referral advice was 88% (22/25; total 70 recommendations). Pharmacists expressed uncertainty when screening for serious pathology in 40% (10/25) of cases. Pharmacists requested more direction from the CDSS in relation to automated prompts for user input and page navigation. Overall system usability was rated as excellent (mean score 92/100, SD 6.5; 90th percentile compared with similar systems), with acceptance rated as good to excellent.

Conclusions

A novel CDSS (high-fidelity prototype) to enhance pharmacist care of LBP was developed, underpinned by clinical practice guidelines and informed by a multidisciplinary team of experts. User-testing revealed a high level of usability and acceptance of the prototype system, with suggestions to improve interface prompts and information delivery. The small study sample limits the generalizability of the findings but offers important insights to inform the next stage of system development.

Efficacy and harms of orally, intramuscularly or intravenously administered glucocorticoids for sciatica: A systematic review and meta-analysis

BACKGROUND

Sciatica can be a debilitating condition and there is limited guidance on the use of glucocorticoids administered via the oral, intramuscular or intravenous route for this condition. These represent viable treatment options in the primary care setting.

OBJECTIVE

To evaluate the evidence on efficacy and harms of oral, IM and IV glucocorticoid administration for sciatica.

DATABASES AND DATA TREATMENT

MEDLINE, EMBASE, CENTRAL, CINAHL, PsycINFO (inception to October 2018) were searched for randomised placebo-controlled trials evaluating oral, IV or IM glucocorticoid administration for sciatica. Two authors extracted outcomes data. Continuous pain and disability outcomes were converted to a 0 (no pain/disability) to 100 (worst pain/disability) scale. Data were pooled using a random effects model. Overall quality of evidence was assessed using GRADE. Primary outcomes were leg pain and disability. Primary follow-up period was the immediate-term (<2 weeks from administration). We also considered adverse events.

RESULTS

Nine trials were eligible. One study [n = 27] provided low quality evidence of a small reduction in disability with early administration of oral prednisone (within 1 week); MD -13.4 [-23.3, -3.5] but not for pain MD -2.5 [-16.9, 11.9]. There was low quality evidence from one study [n = 78] of moderate reduction in disability and small reduction in pain with early (within 72 hr of symptom onset) single intramuscular administration of methylprednisolone acetate; MD -24.5 [-38.8, -10.2] and -14.0 [-27.4, -0.6], respectively. There were no immediate-term benefits with IV administration.

CONCLUSION

The effects of glucocorticoids on immediate-term leg pain or disability are uncertain. Future large high quality trials are needed to resolve this uncertainty.

Is the use of metformin in patients undergoing dialysis hazardous for life? A systematic review of the safety of metformin in patients undergoing dialysis

AIMS

Metformin may have clinical benefits in dialysis patients; however, its safety in this population is unknown. This systematic review evaluated the safety of metformin in dialysis patients.

METHODS

MEDLINE, Embase, CENTRAL, PsycINFO and the Cochrane Library were searched for randomised controlled trials and observational studies evaluating metformin use in dialysis patients. Three authors reviewed the studies and extracted data. The primary outcomes were mortality, occurrence of lactic acidosis and myocardial infarction (MI) in patients taking metformin during dialysis treatment for ≥12 months (long term). Risk of bias was assessed using Risk Of Bias In Nonrandomised Studies of Interventions (ROBINS-1). Overall quality of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

Fifteen observational studies were eligible; 7 were prospective observational studies and 8 were case reports/case series. No randomised controlled trials were identified. The 7 prospective observational studies (n = 194) reported on cautious metformin use in patients undergoing maintenance dialysis. Only 3 provided long-term follow-up data. In 2 long-term studies of metformin therapy (≤1000 mg/d) in patients undergoing peritoneal dialysis (PD), 1 reported 6 deaths (6/83; 7%) due to major cardiovascular events (3 MI) and the other reported no deaths (0/35). One long-term study of metformin therapy (250 mg to 500 mg thrice weekly) in patients undergoing haemodialysis reported 4 deaths (4/61; 7%) due to major cardiovascular events (2 MI). These findings provide very low-quality evidence as they come from small observational studies.

CONCLUSION

The evidence regarding the safety of metformin in people undergoing dialysis is inconclusive. Appropriately designed randomised controlled trials are needed to resolve this uncertainty.

Management of low back pain in Australian emergency departments

Background

To describe the diagnoses of people who present to the emergency department (ED) with low back pain (LBP), the proportion of people with a lumbar spine condition who arrived by ambulance, received imaging, opioids and were admitted to hospital; and to explore factors associated with these four outcomes.

Methods

In this retrospective study, we analysed electronic medical records for all adults presenting with LBP at three Australian EDs from January 2016 to June 2018. Outcomes included discharge diagnoses and key aspects of care (ambulance transport, lumbar spine imaging, provision of opioids, admission). We explored factors associated with these care outcomes using multilevel mixed-effects logistic regression models and reported data as ORs.

Results

There were 14 024 presentations with a ‘visit reason’ for low back pain, of which 6393 (45.6%) had a diagnosis of a lumbar spine condition. Of these, 31.4% arrived by ambulance, 23.6% received lumbar imaging, 69.6% received opioids and 17.6% were admitted to hospital. Older patients (OR 1.79, 95% CI 1.56 to 2.04) were more likely to be imaged. Opioids were less used during working hours (OR 0.81, 95% CI 0.67 to 0.98) and in patients with non-serious LBP compared with patients with serious spinal pathology (OR 1.65, 95% CI 1.07 to 2.55). Hospital admission was more likely to occur during working hours (OR 1.74, 95% CI 1.48 to 2.05) and for those who arrived by ambulance (OR 2.98, 95% CI 2.53 to 3.51).

Conclusion

Many ED presentations of LBP were not due to a lumbar spine condition. Of those that were, we noted relatively high rates of lumbar imaging, opioid use and hospital admission.

Transcutaneous electric nerve stimulation (TENS) for acute low back pain: systematic review

Background and aims There has been no comprehensive evaluation of the efficacy of transcutaneous electric nerve stimulation (TENS) for acute low back pain (LBP). The aim of this systematic review was to investigate the efficacy and safety of TENS for acute LBP. Methods We searched MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, CENTRAL, CINAHL and PsycINFO (inception to May 2018) for randomised placebo controlled trials. The primary outcome measure was pain relief in the immediate term (within 2-weeks of administration) assessed using the 100 mm visual analogue scale. A mean difference of at least 10 points on the 100-point pain scale was considered clinically significant. Methodological quality of the eligible studies was assessed using the PEDro scale and overall quality assessment rating was assessed using GRADE. Results Three placebo controlled studies (n = 192) were included. One low quality trial (n = 63) provides low quality evidence that ~30 min treatment with TENS in an emergency-care setting provides clinically worthwhile pain relief for moderate to severe acute LBP in the immediate term compared with sham TENS [Mean Difference (MD) - 28.0 (95% CI - 32.7, -23.3)]. Two other studies which administered a course of TENS over 4-5 weeks, in more usual settings provide inconclusive evidence; MD -2.75 (95% CI -11.63, 6.13). There was limited data on adverse events or long term follow-up. Conclusions The current evidence is insufficient to support or dismiss the use of TENS for acute LBP. Implications There is insufficient evidence to guide the use of TENS for acute LBP. There is low quality evidence of moderate improvements in pain with a short course of TENS (~30 min) during emergency transport of patients to the hospital. Future research should evaluate whether TENS has an opioid sparing role in the management of acute LBP.

Combination Therapy with an SGLT2 Inhibitor as Initial Treatment for Type 2 Diabetes: A Systematic Review and Meta-Analysis

Background: Guidelines differ with regard to indications for initial combination pharmacotherapy for type 2 diabetes. Aims: To compare the efficacy and safety of (i) sodium-glucose cotransporter 2 (SGLT2) inhibitor combination therapy in treatment-naïve type 2 diabetes adults; (ii) initial high and low dose SGLT2 inhibitor combination therapy. Methods: PubMed, Embase and Cochrane Library were searched for randomised controlled trials (RCTs) of initial SGLT2 combination therapy. Mean difference (MD) for changes from baseline (HbA1c, weight, blood pressure) after 24–26 weeks of treatment and relative risks (RR, safety) were calculated using a random-effects model. Risk of bias and quality of evidence was assessed. Results: In 4 RCTs (n = 3749) there was moderate quality evidence that SGLT2 inhibitor/metformin combination therapy resulted in a greater reduction in HbA1c (MD (95% CI); −0.55% (−0.67, −0.43)) and weight (−2.00 kg (−2.34, −1.66)) compared with metformin monotherapy, and a greater reduction in HbA1c (−0.59% (−0.72, −0.46)) and weight (−0.57 kg (−0.89, −0.25)) compared with SGLT2 inhibitor monotherapy. The high dose SGLT2 inhibitor/metformin combination resulted in a similar HbA1c but greater weight reduction; −0.47 kg (−0.88, −0.06) than the low dose combination therapy. The RR of genital infection with combination therapy was 2.22 (95% CI 1.33, 3.72) and 0.69 (95% CI 0.50, 0.96) compared with metformin and SGLT2 inhibitor monotherapy, respectively. The RR of diarrhoea was 2.23 (95% CI 1.46, 3.40) with combination therapy compared with SGLT2 inhibitor monotherapy. Conclusions: Initial SGLT2 inhibitor/metformin combination therapy has glycaemic and weight benefits compared with either agent alone and appears relatively safe. High dose SGLT2 inhibitor/metformin combination therapy appears to have modest weight, but no glycaemic benefits compared with the low dose combination therapy.

Clinicopathologic and Prognostic Significance of Programmed Cell Death Ligand 1 Expression in Patients with Non-Medullary Thyroid Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Evidence has shown that programmed cell death ligand 1 (PD-L1) overexpression is associated with poor prognosis and resistance to immune therapies in several human cancers. However, data on the prognostic significance of PD-L1 expression in thyroid cancer are limited and remain controversial. This systematic review and meta-analysis aimed to evaluate comprehensively the clinicopathologic significance and prognostic value of PD-L1 expression in non-medullary thyroid cancers.

METHODS

Electronic databases, including Medline/PubMed, EMBASE, and the Cochrane Library, were searched up until July 5, 2017. In total, seven comparisons (from six articles) comprising 1421 patients were included in the pooled analysis.

RESULTS

There was moderate quality evidence from four studies (n = 721) that shows positive PD-L1 expression was significantly associated with poor survival among thyroid cancer patients (pooled hazard ratio = 3.73 [confidence interval (CI) 2.75-5.06]). Increased PD-L1 expression was also found to be significantly associated with disease recurrence (odds ratio = 1.95 [CI 1.15-3.32]) and concurrent thyroiditis (odds ratio = 1.65 [CI 1.09-2.51]).

CONCLUSIONS

The results confirm the prognostic significance of PD-L1 expression in thyroid cancer patients. PD-L1 expression has the potential to be implemented as a prognostic biomarker used to guide clinicians in identifying patients with more aggressive cancers, and for the selection of individuals that would derive durable clinical benefit from anti-PD-1/PD-L1 immunotherapy. Prospective clinical trials will be useful to support these findings.

Comparison of effect sizes between enriched and nonenriched trials of analgesics for chronic musculoskeletal pain: a systematic review

AIMS

To investigate the use of an enriched study design on the estimates of treatment effect in analgesic trials for chronic musculoskeletal pain.

METHODS

Database searches were conducted from 2004 to 2014. We included randomized placebo-controlled trials evaluating pain medications for chronic musculoskeletal pain. Methodological quality was assessed using the PEDro scale. The estimates of treatment effect on pain and adverse events were compared between enriched and nonenriched designs. Metaregression was used to assess the association between the effect size estimate and the study design controlling for analgesic dose and methodological quality.

RESULTS

We included 108 trials, of which 99 were included in the meta-analysis (n = 44 171). There were no overall differences in effect sizes between enriched and nonenriched designs for pain intensity. There was a significant difference for a reduction in any adverse events favouring enriched designs for opioids, but not for other analgesics or the outcome serious adverse events. There was an association between effect size and methodological quality, with failure to blind the outcome assessor and failure to use intention-to-treat analysis being associated with larger effect sizes.

CONCLUSIONS

There is no evidence that the use of an enriched study design changes the treatment effect size estimate for pain. There is some evidence that clinical trials that employ enriched designs report a reduced risk of adverse events in trials for chronic musculoskeletal pain, but it is unclear whether enriched designs influence estimates of serious adverse events. Features of trial design and study quality were associated with treatment effect estimates.

Pharmacists' views on implementing a disease state management program for low back pain

Pharmacists have the potential to take a lead role in the primary care management of people with acute low back pain. The aim of this study was to investigate pharmacists' views on implementing a care program for people with acute low back pain in the community pharmacy. Recruitment of pharmacists for this study took place between July 2012 and March 2013. A convenience sample of 30 pharmacists who collaborated in recruiting participants for a low back pain clinical trial in Sydney (n=15 pharmacist recruiters and n=15 non-recruiters) completed an open-ended questionnaire. There was no marked variation in responses between the two groups. Participating pharmacists were receptive to the idea of implementing a care program for people with low back pain, highlighting the need for adequate reimbursement and adequate training of staff to ensure it is successful. Pharmacists identified that the follow up of people receiving such a service is dependent on several factors such as effective reminder systems and the proximity of patients to the pharmacy.

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.