An Updated Systematic Review and Meta-analysis of Duloxetine for Knee Osteoarthritis Pain

Systematic reviews and meta-analyses in regional anesthesia and pain medicine (Part I): guidelines for preparing the review protocol

Comprehensive resources exist on how to plan a systematic review and meta-analysis. The objective of this article is to provide guidance to authors preparing their systematic review protocol in the fields of regional anesthesia and pain medicine. The focus is on systematic reviews of healthcare interventions, with or without an aggregate data meta-analysis. We describe and discuss elements of the systematic review methodology that review authors should prespecify, plan, and document in their protocol before commencing the review. Importantly, authors should explain their rationale for planning their systematic review and describe the PICO framework-participants (P), interventions (I),comparators (C), outcomes (O)-and related elements central to constructing their clinical question, framing an informative review title, determining the scope of the review, designing the search strategy, specifying the eligibility criteria, and identifying potential sources of heterogeneity. We highlight the importance of authors defining and prioritizing the primary outcome, defining eligibility criteria for selecting studies, and documenting sources of information and search strategies. The review protocol should also document methods used to evaluate risk of bias, quality (certainty) of the evidence, and heterogeneity of results. Furthermore, the authors should describe their plans for managing key data elements, the statistical construct used to estimate the intervention effect, methods of evidence synthesis and meta-analysis, and conditions when meta-analysis may not be possible, including the provision of practical solutions. Authors should provide enough detail in their protocol so that the readers could conduct the study themselves.

Systematic Reviews and Meta-analyses in Regional Anesthesia and Pain Medicine (Part I): Guidelines for Preparing the Review Protocol

Comprehensive resources exist on how to plan a systematic review and meta-analysis. The objective of this article is to provide guidance to authors preparing their systematic review protocol in the fields of regional anesthesia and pain medicine. The focus is on systematic reviews of health care interventions, with or without an aggregate data meta-analysis. We describe and discuss elements of the systematic review methodology that review authors should prespecify, plan, and document in their protocol before commencing the review. Importantly, authors should explain their rationale for planning their systematic review and describe the PICO framework-participants (P), interventions (I), comparators (C), outcomes (O)-and related elements central to constructing their clinical question, framing an informative review title, determining the scope of the review, designing the search strategy, specifying the eligibility criteria, and identifying potential sources of heterogeneity. We highlight the importance of authors defining and prioritizing the primary outcome, defining eligibility criteria for selecting studies, and documenting sources of information and search strategies. The review protocol should also document methods used to evaluate risk of bias, quality (certainty) of the evidence, and heterogeneity of results. Furthermore, the authors should describe their plans for managing key data elements, the statistical construct used to estimate the intervention effect, methods of evidence synthesis and meta-analysis, and conditions when meta-analysis may not be possible, including the provision of practical solutions. Authors should provide enough detail in their protocol so that the readers could conduct the study themselves.

Central Sensitization and Pain: Pathophysiologic and Clinical Insights

Central sensitization is an increased responsiveness of nociceptive neurons in the central nervous system to their normal or subthreshold afferent input.

AIM

To explain how the notion of central sensitization has changed our understanding of pain conditions, discuss how this knowledge can be used to improve the management of pain, and highlight knowledge gaps that future research needs to address.

METHODS

Overview of definitions, assessment methods, and clinical implications.

RESULTS

Human pain models, and functional and molecular imaging have provided converging evidence that central sensitization occurs and is clinically relevant. Measures to assess central sensitization in patients are available; however, their ability to discriminate sensitization of central from peripheral neurons is unclear. Treatments that attenuate central sensitization are available, but the limited understanding of molecular and functional mechanisms hampers the development of target-specific treatments. The origin of central sensitization in human pain conditions that are not associated with tissue damage remains unclear.

CONCLUSION

The knowledge of central sensitization has revolutionized our neurobiological understanding of pain. Despite the limitations of clinical assessment in identifying central sensitization, it is appropriate to use the available tools to guide clinical decisions towards treatments that attenuate central sensitization. Future research that elucidates the causes, molecular and functional mechanisms of central sensitization would provide crucial progress towards the development of treatments that target specific mechanisms of central sensitization.

[Concept for integrative pain treatment of osteoarthritis of the knee based on the evidence for conservative and complementary therapies]

BACKGROUND

Osteoarthritis of the knee (gonarthritis) represents a medical challenge.

RESEARCH QUESTION

What is the evidence with respect to approaches of complementary medicine and their integration into multimodal pain management concepts?

MATERIAL AND METHODS

Qualitative nonsystematic literature search on the epidemiology and pathophysiology as well as informative clinical trials, meta-analyses and clinical guidelines about conservative treatment including complementary therapy for gonarthritis.

RESULTS

Osteoarthritis of the knee is a frequent condition with biopsychosocial risks factors for chronification. The German S2k clinical guideline (k = consensus-based, not based on scientific systematic literature searches) published by the Association of the Scientific Medical Societies in Germany (AWMF) in 2017 has not yet been updated. The current guidelines of the American College of Rheumatology (ACR) date from 2020. Both guidelines recommend exercise therapy, weight reduction, short-term analgesics, topical therapy, intra-articular corticoid injections and acupuncture with variable strengths. Furthermore, transcutaneous electrical nerve stimulation (TENS), laser and other electrophysical therapies, shock waves, traction treatment, ergotherapy, comfrey poultices and mudpacks can also be used. Current research supports the benefits of tai chi/qigong and medicinal leaches.

CONCLUSION

Complementary treatment approaches, such as acupuncture, tai chi/qigong, topical naturopathic self-treatment and leeches (with limitations) can, in addition to behavioral changes, exercise therapy and short-term pharmacological treatment, be important evidence-based components of integrative pain management concepts, e.g. in terms of an interdisciplinary multimodal pain treatment (IMPT). Besides pain reduction and functional improvement they promote the internal control conviction through the possibility of self-treatment and self-exercise.

The efficacy and safety of duloxetine for the treatment of patients after TKA or THA: A systematic review and meta-analysis

BACKGROUND

Duloxetine, a serotonin-norepinephrine dual reuptake inhibitor, may improve analgesia after total joint arthroplasty (TJA). However, there is still no consensus on its effectiveness and safety. We conducted the meta-analysis to investigate the analgesic effect and safety of duloxetine for the treatment of patients received total knee or hip arthroplasty.

METHODS

Pubmed, Cochrane Central Registry for Clinical Trials, Embase, OVID, Web of Science, and Google Scholar were searched using a predetermined search strategy from inception to September 21, 2022. Only randomized controlled trials of duloxetine in treatment of patients after total knee or hip arthroplasty were included. Data collection and extraction, quality assessment, and data analyses were performed according to the Cochrane standards.

RESULTS

A total of 8 randomized controlled trials with 739 patients were included in the literature review of postoperative pain and adverse effects. The result of meta-analysis showed statistically significant lower opioid requirement with duloxetine (P < .05) for the different postoperative period. Duloxetine group had significant reductions in visual analog score for the 24-hour (walking: WMD = -0.98; 95% confidence interval [CI] = -1.69 to -0.26, P = .007; resting: WMD = -1.06; 95%CI = -1.85 to -0.27, P = .008) and 1-week (walking: WMD = -0.96; 95%CI = -1.42 to -0.50, P < .001; resting: WMD = -0.69; 95%CI = -1.22 to -0.16, P = .01); knee injury and osteoarthritis outcome score over 3-month (WMD = 2.94; 95%CI = -0.30 to 6.18, P = .008) and complication (odds ratio = 4.74; 95%CI = 0.23 to 96.56, P = .01) postoperative period compared with the control group. However, no difference on numeric rating scale (P > .05) for the different postoperative period; visual analog score (P > .05) for the 6-week or 3-month and knee injury and osteoarthritis outcome score (P > .05) for the 6-week postoperative period. Furthermore, it did not increase the incidence of adverse effects (odds ratio = 0.87; 95%CI = 0.72 to 1.05, P = .15).

CONCLUSION

Duloxetine could decrease the opioids consumption and relieve early postoperative pain without increasing the risk of adverse medication effects in patients undergoing total knee or hip arthroplasty. Considering the ongoing opioid epidemic, duloxetine could act as a good supplement in multimodal pain management protocol for patients undergoing total joint arthroplasty.

Predicting pain after standard pain therapy for knee osteoarthritis - the first steps towards personalized mechanistic-based pain medicine in osteoarthritis

OBJECTIVES

The prevalence of osteoarthritis (OA) is rising, and pain is the hallmark symptom of OA. Pain in OA is complicated and can be influenced by multiple joint-related factors and factors related to, e.g., physiological, epigenetic, and pain sensory profiles. Increasing evidence suggests that a subset of patients with OA are pain sensitive. This can be assessed using quantitative sensory testing (QST). Common treatments of OA are total knee arthroplasty (TKA) and administration of 3-weeks of non-steroidal anti-inflammatory drugs (NSAIDs), which provide pain relief to many patients with OA. However, approx. 20% of patients experience chronic postoperative pain after TKA, whereas NSAIDs provide an average pain relief of approx. 25%. The current topical review focuses on the emerging evidence linking pretreatment QST to the treatment response of TKA and NSAID treatments.

CONTENT

MEDLINE was systematically searched for all studies from 2000 to 2022 on pretreatment QST, TKA, and NSAIDs. Pre-clinical studies, reviews, and meta-analyses were excluded.

SUMMARY

Currently, 14 studies on TKA and four studies on NSAIDs have been published with the aim to attempt prediction of the treatment response. The QST methodologies in the studies are inconsistent, but 11/14 (79%) studies on TKA and 4/4 (100%) studies on NSAIDs report statistically significant associations between pretreatment QST and chronic postoperative pain after TKA or analgesic effect after NSAID treatment. The strength of the associations remains low-to-moderate. The most consistent pretreatment QST predictors are pressure pain thresholds, temporal summation of pain, and conditioned pain modulation.

OUTLOOK

The use of QST as predictors of standard OA treatment is interesting, but the predictive strength remains low-to-moderate. A transition of QST from a research-based setting and into the clinic is not advised until the predictive strength has been improved and the methodology has been standardized.

The Effectiveness of Duloxetine for Knee Osteoarthritis: An Overview of Systematic Reviews

Background: Knee osteoarthritis (KOA) has become a public health problem. Several systematic reviews (SRs) have reported that duloxetine may be an effective treatment for improving pain and depressive symptoms in patients with KOA.

Aim: To evaluate the available results and provide scientific evidence for the efficacy and safety of duloxetine for KOA.

Methods: A comprehensive search strategy was conducted across eight databases from inception to 31 December 2021. Two researchers independently selected eligible studies, collected data and evaluated those included SRs’ quality. For assessing methodological quality, the Assessing the Methodological Quality of Systematic Reviews 2 (AMSTAR 2) was employed. Risk of Bias in Systematic Reviews (ROBIS) was used to assess the risk of bias. Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) was utilized for assessing reporting quality. In addition, the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to determine primary outcome indicators’ evidence quality.

Results: Totally 6 SRs were contained in this overview. After assessment based on AMSTAR 2, ROBIS, and PRISMA, unsatisfactory results in terms of methodological quality, risk of bias as well as reporting quality, were obtained. Limitations included a search of grey literature, the reasons for selecting the study type, an excluded study list and the specific reasons, reporting bias assessment, and reporting of potential sources of conflict of interest. According to the GRADE results, the evidence quality was high in 0, moderate in 5, low in 19, and very low in 36. Limitations were the most commonly downgraded factor, followed by publication bias and inconsistency.

Conclusion: Duloxetine may be an effective treatment for improving pain and depressive symptoms in KOA patients with acceptable adverse events. However, due to the low quality of the available evidence, the original study design and the quality of evidence from SRs should be further improved, so as to provide strong scientific evidence for definitive conclusions.

Systematic Review Registration: PROSPERO; (http://www.crd.york.ac.uk/PROSPERO/), identifier (CRD42021289823).

The Effect of Duloxetine on Mechanistic Pain Profiles, Cognitive Factors, and Clinical Pain in Patients with Painful Knee Osteoarthritis - A Randomized, Double-Blind, Placebo-Controlled, Crossover Study

BACKGROUND

Duloxetine is indicated in the management of pain in osteoarthritis. Evidence suggests that duloxetine modulate central pain mechanisms and cognitive factors, and these factors are assumed contributing to the analgesic effect. This proof-of-mechanism, randomized, placebo-controlled, crossover, double-blinded trial evaluated the effect of duloxetine on quantitative sensory testing (QST), cognitive factors, and clinical pain in patients with osteoarthritis and to predict the analgesic effect.

METHODS

Twenty-five patients completed this cross-over study with either 18-weeks duloxetine (maximum 60 mg/daily) followed by placebo or vice-versa. Pressure pain thresholds, temporal summation of pain, and conditioned pain modulation were assessed using cuff algometry. The Hospital Anxiety and Depression Scale and the Pain Catastrophizing Scale evaluated cognitive factors. Clinical pain was assessed using Brief Pain Inventory and Western Ontario and McMaster Universities Osteoarthritis Index. Linear regression models were used to predict the analgesic effect of duloxetine.

RESULTS

Depending on the clinical pain outcome, 40-68% of patients were classified as responders to duloxetine. Linear regression models predicted the analgesic effect (predictive value of 45-75% depending on clinical pain outcome parameter) using a combination of pre-treatment QST parameters, cognitive factors, and clinical pain. No significant changes were found for QST, cognitive factors, or clinical pain on a group level when comparing duloxetine to placebo.

CONCLUSION

A combination of pre-treatment QST, cognitive factors, and clinical pain was able to predict the analgesic response of duloxetine. However, in this relatively small study, duloxetine did not selectively modulate QST, cognitive factors, or clinical pain intensity when compared with placebo.

A mechanism-based proof of concept study on the effects of duloxetine in patients with painful knee osteoarthritis

BACKGROUND

The global burden of osteoarthritis (OA) is steadily increasing due to demographic and lifestyle changes. The nervous system can undergo peripheral and central neuroplastic changes (sensitization) in patients with OA impacting the options to manage the pain adequately. As a result of sensitization, patients with OA show lower pressure pain thresholds (PPTs), facilitated temporal summation of pain (TSP), and impaired conditioned pain modulation (CPM). As traditional analgesics (acetaminophen and non-steroidal anti-inflammatory drugs) are not recommended for long-term use in OA, more fundamental knowledge related to other possible management regimes are needed. Duloxetine is a serotonin-noradrenalin reuptake inhibitor, and analgesic effects are documented in patients with OA although the underlying fundamental mechanisms remain unclear. The descending pain inhibitory control system is believed to be dependent on serotonin and noradrenalin. We hypothesized that the analgesic effect of duloxetine could act through these pathways and consequently indirectly reduce pain and sensitization. The aim of this mechanistic study is to investigate if PPTs, TSP, CPM, and clinical pain parameters are modulated by duloxetine.

METHODS

This proof of concept study is a randomized, placebo-controlled, double-blinded, crossover trial, which compares PPTs, TSP, and CPM before and after 18 weeks of duloxetine and placebo in forty patients with knee OA. The intervention periods include a titration period (2 weeks), treatment period (60 mg daily for 14 weeks), and a discontinuation period (2 weeks). Intervention periods are separated by 2 weeks.

DISCUSSION

Duloxetine is recommended for the treatment of chronic pain, but the underlying mechanisms of the analgesic effects are currently unknown. This study will investigate if duloxetine can modify central pain mechanisms and thereby provide insights into the underlying mechanisms of the analgesic effect.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04224584 . Registered on January 6, 2020. EudraCT 2019-003437-42 . Registered on October 22, 2019. The North Denmark Region Committee on Health Research Ethics N-20190055. Registered on October 31, 2019.