Placebo effects in low back pain: A systematic review and meta-analysis of the literature

Are some people more susceptible to placebos? A systematic review and meta-analysis of inter-individual variability in musculoskeletal pain

Existing data suggest placebo responses to treatments are small, but some people may be more likely to respond. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) on interindividual variability in response to placebo interventions MEDLINE, EMBASE, CINAHL, Web of Science Core Collection, CENTRAL, and SPORTDiscus were searched from inception to September 2023. Trial registry searches, citation tracking, and searches for prior systematic reviews were completed. The PEDro scale assessed study quality. Random effects robust variance estimation estimated the log variability ratio (VR), identifying subgroups with varying responses. Twenty-six studies were included, comprising various musculoskeletal pain conditions. Analysis of pain intensity (VR: 1.06, 95%-confidence interval (CI):[0.97; 1.16], 95%-prediction interval (PI):[0.75; 1.51], p = 0.17, k = 26 studies, N = 52 outcomes, GRADE: low), physical function (VR: 1.14, 95%-CI:[0.97; 1.34], 95%-PI:[0.62; 2.11], p = 0.11, k = 19, N = 40, GRADE: low), and health-related quality of life (VR: 1.14, 95%-CI:[0.91; 1.41], 95%-PI:[0.72; 1.80], p = 0.19, k = 7, N = 13, GRADE: low) outcomes revealed minimal, non-statistically significant variability in placebo response compared to control. However, wide prediction intervals suggest uncertainty regarding individual response patterns. There are likely no distinct subgroups of people who are more likely to respond to placebo interventions in musculoskeletal pain; although the available data limits the certainty of this assessment. Future work should consider individual participant data meta-analyses to better elucidate potential responder subgroups and optimize treatment strategies for musculoskeletal pain. PERSPECTIVE: This study systematically reviewed and analyzed RCTs to assess interindividual variability in placebo responses for musculoskeletal pain. Findings suggest minimal variability in placebo response, with no distinct subgroups more likely to respond. Wide prediction intervals indicate uncertainty, highlighting the need for future individual participant data meta-analyses to better elucidate potential responder subgroups.

The impact of contextual effects in exercise therapy for low back pain: a systematic review and meta-analysis

BACKGROUND

Low back pain is the leading cause of global disability for which exercise therapy is a widely recommended treatment. Research indicates that contextual factors may also influence treatment outcomes in low back pain. Examples include the patient-therapist relationship and other treatment-related circumstances that affect patient expectations. By focusing on the specific treatment effect, clinical trials often ignore the effect of contextual factors, thereby contributing to the so-called efficacy paradox. This means that treatment effects observed in clinical practice are often greater than those reported in clinical trials. This systematic review aims to investigate the proportion of improvement in pain and disability that can be attributed to contextual effects in the outcome of exercise therapy for patients with low back pain.

METHODS

A meta-analysis was conducted. PubMed, Embase, and the Cochrane database were searched for eligible articles reporting randomized controlled trials that compared exercise therapy to placebo interventions. Risk of bias was assessed with the Revised Cochrane Risk of Bias Tool. Outcomes of interest were pain and disability. Meta-analysis was carried out to calculate the proportion attributable to contextual effects for both pain and disability. The body of evidence was assessed using the GRADE methodology.

RESULTS

Eight studies met the inclusion criteria and were included in the meta-analysis. Five studies were rated as having a moderate risk of bias and two studies had a low risk of bias. Proportion attributable to contextual effects was 0.60 (95% CI 0.40-0.89) for pain and 0.69 (95% CI 0.48-1.00) for disability. Certainty of the evidence as assessed with the GRADE methodology was low.

CONCLUSIONS

A large extent of pain and disability improvement after exercise therapy in low back pain is attributable to contextual effects although this conclusion is based on low certainty evidence.

Pain, mindfulness, and placebo: a systematic review

Introduction

Pain is a complex phenomenon influenced by psychosocial variables, including the placebo effect. The effectiveness of mindfulness-based interventions (MBIs) for pain has been demonstrated in experimental studies and systematic reviews, but the mechanisms of action are only starting to be established. Whether the expectations of individuals experiencing pain can be manipulated during MBIs remains to be systematically evaluated, and what role placebo effects might play remains to be explored.

Methods

To evaluate the literature analyzing placebo effects in MBIs for pain, we performed a systematic review based on searches conducted in PubMed, Web of Science, and SCOPUS databases. Our search revealed a total of 272 studies, of which only 19 studies were included (10 acute pain and nine chronic pain), considering the inclusion and exclusion criteria related to expectations and placebo effects.

Results

From the 19 included studies, six measured placebo effects only in relation to the pharmacological intervention used in the study and not to an MBI.

Discussion

The results of the few studies that focused on the placebo effects of the MBIs indicate that placebo and expectations play a role in the MBIs' effects on pain. Although expectations and placebo effects are frequently discussed in the context of mindfulness and pain research, these results show that these factors are still not routinely considered in experimental designs. However, the results of the few studies included in this systematic review highlight a clear role for placebo and expectancy effects in the overall effects of MBIs for both acute and chronic pain, suggesting that routine measurement and further consideration in future studies are warranted. Additional research in this fascinating and challenging field is necessary to fully understand the connection between MBIs, placebo/expectations, and their effects on pain relief.

Reduction of Chronic Primary Low Back Pain by Spinal Manipulative Therapy is Accompanied by Decreases in Segmental Mechanical Hyperalgesia and Pain Catastrophizing: A Randomized Placebo-controlled Dual-blind Mixed Experimental Trial

Chronic primary low back pain (CPLBP) refers to low back pain that persists over 3 months, that cannot be explained by another chronic condition, and that is associated with emotional distress and disability. Previous studies have shown that spinal manipulative therapy (SMT) is effective in relieving CPLBP, but the underlying mechanisms remain elusive. This randomized placebo-controlled dual-blind mixed experimental trial (NCT05162924) aimed to investigate the efficacy of SMT to improve CPLBP and its underlying mechanisms. Ninety-eight individuals with CPLBP and 49 controls were recruited. Individuals with CPLBP received SMT (n = 49) or a control intervention (n = 49), 12 times over 4 weeks. The primary outcomes were CPLBP intensity (0-100 on a numerical rating scale) and disability (Oswestry Disability Index). Secondary outcomes included pressure pain thresholds in 4 body regions, pain catastrophizing, Central Sensitization Inventory, depressive symptoms, and anxiety scores. Individuals with CPLBP showed widespread mechanical hyperalgesia (P < .001) and higher scores for all questionnaires (P < .001). SMT reduced pain intensity compared with the control intervention (mean difference: -11.7 [95% confidence interval, -11.0 to -12.5], P = .01), but not disability (P = .5). Similar mild to moderate adverse events were reported in both groups. Mechanical hyperalgesia at the manipulated segment was reduced after SMT compared with the control intervention (P < .05). Pain catastrophizing was reduced after SMT compared with the control intervention (P < .05), but this effect was not significant after accounting for changes in clinical pain. Although the reduction of segmental mechanical hyperalgesia likely contributes to the clinical benefits of SMT, the role of pain catastrophizing remains to be clarified. PERSPECTIVE: This randomized controlled trial found that 12 sessions of SMT yield greater relief of CPLBP than a control intervention. These clinical effects were independent of expectations, and accompanied by an attenuation of hyperalgesia in the targeted segment and a modulation of pain catastrophizing.

Can observational learning reinforce open-label placebo hypoalgesia?

ABSTRACT

Previous research has indicated that an open-label placebo can reduce pain in both healthy participants and patients with chronic pain. Because nondeceptive placebos seem to be an effective and more ethical alternative to deceptive placebos, optimizing this kind of treatment is essential. Observational learning was previously shown to induce the deceptive placebo effect; therefore, this study aimed to verify its effectiveness in fortifying the open-label placebo effect. Healthy volunteers (N = 117) were randomly assigned to 4 groups: open-label placebo with observational learning (OLP + OBL), open-label placebo (OLP), deceptive placebo with observational learning (OBL), or control group. Participants underwent baseline and testing measurements, during which they self-reported pain induced by heat stimulation. Between assessments, placebo cream was openly administered in the OLP and OLP + OBL groups. The OLP + OBL group next watched a model experiencing hypoalgesia after cream application. In the OBL group, participants received placebo cream with no information about its effect, and then they watched the model. The placebo effect was successfully evoked in all experimental groups (OLP + OBL, OLP, and OBL), which confirms the effectiveness of both open-label and deceptive placebo interventions for pain reduction. However, the hypoalgesic effect was of similar magnitude in the OLP and OLP + OBL groups, which indicates that observation did not contribute to the effect. The results showed that reinforcing the open-label placebo by observational learning may be redundant, but more research is needed to confirm these findings.

The importance of context (placebo effects) in conservative interventions for musculoskeletal pain: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVE

Contextual effects (e.g. patient expectations) may play a role in treatment effectiveness. This study aimed to estimate the magnitude of contextual effects for conservative, non-pharmacological interventions for musculoskeletal pain conditions. A systematic review and meta-analysis of randomized controlled trials (RCTs) that compared placebo conservative non-pharmacological interventions to no treatment for musculoskeletal pain. The outcomes assessed included pain intensity, physical functioning, health-related quality of life, global rating of change, depression, anxiety and sleep at immediate, short-, medium- and/or long-term follow-up.

DATABASES AND DATA TREATMENT

MEDLINE, EMBASE, CINAHL, Web of Science Core Collection, CENTRAL and SPORTDiscus were searched from inception to September 2021. Trial registry searches, backward and forward citation tracking and searches for prior systematic reviews were completed. The Cochrane risk of bias 2 tool was implemented.

RESULTS

The study included 64 RCTs (N = 4314) out of 8898 records. For pain intensity, a mean difference of (MD: -5.32, 95% confidence interval (CI): -7.20, -3.44, N = 57 studies with 74 outcomes, GRADE: very low) was estimated for placebo interventions. A small effect in favour of the placebo interventions for physical function was estimated (SMD: -0.22, 95% CI: -0.35, -0.09; N = 37 with 48 outcomes, GRADE: very low). Similar results were found for a broad range of patient-reported outcomes. Meta-regression analyses did not explain heterogeneity among analyses.

CONCLUSION

The study found that the contextual effect of non-pharmacological conservative interventions for musculoskeletal conditions is likely to be small. However, given the known effect sizes of recommended evidence-based treatments for musculoskeletal conditions, it may still contribute an important component.

SIGNIFICANCE

Contextual effects of non-pharmacological conservative interventions for musculoskeletal conditions are likely to be small for a broad range of patient-reported outcomes (pain intensity, physical function, quality of life, global rating of change and depression). Contextual effects are unlikely, in isolation, to offer much clinical care. But these factors do have relevance in an overall treatment context as they provide almost 30% of the minimally clinically important difference.

Placebo analgesia in physical and psychological interventions: Systematic review and meta-analysis of three-armed trials

BACKGROUND

The magnitude of placebo effects from physical and psychological 'sham' is unknown but could impact efficacy trials and treatment understanding. To quantify placebo effects, this systematic review of three-armed randomised controlled trials (RCTs) of physical and psychological interventions for pain compared outcomes in 'sham' control intervention and non-exposure arms.

METHODS

RCTs with treatment, 'sham' control intervention, and non-exposure groups were included, enrolling adults with any pain. A protocol was pre-registered (PROSPERO: CRD42023413324), and twelve databases searched from 2008 to July 2023. Trial methods and blinding were analysed descriptively and risk of bias assessed. Meta-analysis of pain measures at short-, medium- and long-term was performed with random-effects models of standardised mean differences (SMD).Studies were sub-grouped according to control intervention type.

RESULTS

Seventeen RCTs were included. The average short-term placebo effect was small (0.21 SMD, 0.1-0.33 95% CI, p = 0.0002, 1440 participants). It showed no heterogeneity (Tau2  = 0.1, I2  = 11%, p = 0.3), preventing meta-regression analyses of effect modifiers. However, sub-group analyses revealed larger placebo effects in manual control interventions compared to disabled devices and miscellaneous control interventions. Overall, placebo analgesia accounted for 39% of treatments' short-term effectiveness. No placebo effects were found at medium-term (7 RCTs, 381 participants) or long-term follow-up (3 RCTs, 173 participants).

CONCLUSIONS

The observed placebo analgesia has mechanistic and methodological implications, though its clinical importance may be limited. Control intervention design affects placebo effects, highlighting the importance of considering methodology in RCT interpretation. Review limitations include a small number of long-term studies and sample heterogeneity.

SIGNIFICANCE

This systematic review directly quantifies placebo effects from physical and psychological 'sham' control interventions and compares them to treatments' overall effectiveness. By doing so, the review enhances our understanding of placebo effects, their relative contribution in clinical trials, and their susceptibly to trial design. It poses further questions regarding the influence of blinding, participant expectations, and features of the therapeutic context. Overall, the insights provided by this review carry methodological significance and are important for the interpretation and synthesis of efficacy trials in this field.

Effects of MLS Laser on pain, function, and disability in chronic non-specific low back pain: A double-blind placebo randomized-controlled trial

BACKGROUND

Among non-pharmacological interventions, Multiwave Locked System (MLS) Laser therapy has been used in patients with several musculoskeletal pathologies and in combination with other therapeutical interventions. The effects of sole MLS therapy on pain and function in patients with chronic non-specific low-back pain are unknown.

OBJECTIVE

The objective of this study was to investigate the effects of MLS Laser therapy on pain, function, and disability in patients with chronic non-specific low back pain in comparison to a placebo treatment group.

METHODS

Forty-five patients were randomized into two groups: the MLS Laser group and the Sham Laser group, undergoing 8 sessions of either a MLS Laser therapy or a Sham Laser therapy, respectively. At the beginning of the therapy (T0), at the end of the therapy (T1), and 1 month after the end of therapy (T2) patients were assessed for low back pain (by means of a VAS scale), function (by means of kinematic and electromyographic assessment of a forward bending movement) and self-reported disability (by means of the Roland-Morris and Oswestry Disability questionnaires).

RESULTS

There was a significant reduction of pain and disability in both groups at T1 and T2 in comparison with T0. At T2 patients in the MLS group showed a significantly lower pain in comparison with patients in the Sham group (VAS = 2.2 ± 2 vs. 3.6 ± 2.4; p< 0.05). No differences between the two groups were found for function and disability.

CONCLUSION

Both MLS Laser and Sham Laser therapies lead to a significant and comparable reduction in pain and disability in patients with chronic non-specific low back pain. However, one month after treatment, MLS Laser therapy has been found to be significantly more effective in reducing pain as compared to sham treatment.

Determinants of outcomes for patients with chronic low back pain and fear-avoidance beliefs following treatment with specific stabilisation exercises

BACKGROUND

Specific stabilisation exercises (SSE) can combat the debilitating effects of chronic non-specific low back pain (CLBP), improve disability, pain and fear-avoidance beliefs (FAB).

OBJECTIVE

To elicit the determinants of outcome in patients with CLBP with associated FABs after treatment with SSE.

METHOD

Twenty-nine patients (20 females) with CLBP were classified using FAB questionnaire into high or low Work and Physical Activity (PA) subscales. After 4-week treatment, evaluations were done for pain, disability and lumbar spine active range of motion (AROM). Data was analysed exploratory-descriptively with a significance level set at p< 0.05.

RESULTS

Participants were aged 55.24 ± 11.91 years. They scored 19 (65.5%) and 5 (17.2%) respectively on Work and PA subscales. The post-intervention evaluation showed significant differences in all outcomes, but no significant difference between patients with high or low FAB scores for both subscales. PA scores correlated significantly with pain while work scores correlated significantly with disability. Participants' gender predicted disability, pain and AROM with moderate to large effect sizes.

CONCLUSION

SSE can potentially improve disability, pain and range of motion for patients with chronic low back pain regardless of FABQ status. Gender and baseline patient status are potential determinants of outcome of treatment using SSE.

A novel computational approach to pain perception modelling within a Bayesian framework using quantitative sensory testing

Pain perception can be studied as an inferential process in which prior information influences the perception of nociceptive input. To date, there are no suitable psychophysical paradigms to measure this at an individual level. We developed a quantitative sensory testing paradigm allowing for quantification of the influence of prior expectations versus current nociceptive input during perception. Using a Pavlovian-learning task, we investigated the influence of prior expectations on the belief about the varying strength of association between a painful electrical cutaneous stimulus and a visual cue in healthy subjects (N = 70). The belief in cue-pain associations was examined with computational modelling using a Hierarchical Gaussian Filter (HGF). Prior weighting estimates in the HGF model were compared with the established measures of conditioned pain modulation (CPM) and temporal summation of pain (TSP) assessed by cuff algometry. Subsequent HGF-modelling and estimation of the influence of prior beliefs on perception showed that 70% of subjects had a higher reliance on nociceptive input during perception of acute pain stimuli, whereas 30% showed a stronger weighting of prior expectations over sensory evidence. There was no association between prior weighting estimates and CPM or TSP. The data demonstrates relevant individual differences in prior weighting and suggests an importance of top-down cognitive processes on pain perception. Our new psychophysical testing paradigm provides a method to identify individuals with traits suggesting greater reliance on prior expectations in pain perception, which may be a risk factor for developing chronic pain and may be differentially responsive to learning-based interventions.

Stratification of Spine Patients based on Self-Reported Clinical Symptom Classes: Evaluation of Long-Term Outcomes and Subsequent Interventions

Background

Prior work by our group developed a stratification tool based on four PROMIS domains for patients with low back pain (LBP). Our study aimed to evaluate the ability of our previously developed symptom classes to predict long-term outcomes, and determine whether there were differential treatment effects by intervention.

Methods

This was a retrospective cohort study of adult patients with LBP seen in spine clinics in a large health system between November 14, 2018 and May 14, 2019 who completed patient-reported outcomes as part of routine care at baseline and again at 12-months follow-up. Latent class analysis identified symptom classes based on PROMIS domain scores (physical function, pain interference, social role satisfaction, and fatigue) that were ≥1 standard deviation worse (meaningfully worse) than the general population. The ability of the profiles to predict long-term outcomes at 12-months was evaluated through multivariable models. Differences in outcomes by subsequent treatments (physical therapy, specialist visits, injections, and surgery) were investigated.

Results

There were 3,236 adult patients (average age 61.1 ± 14.2, 55.4% female) included in the study with three distinct classes identified: mild symptoms (n = 986, 30.5%), mixed (n = 798, 24.7%) with poor scores on physical function and pain interference but better scores on other domains, and significant symptoms (n = 1,452, 44.9%). The classes were significantly associated with long-term outcomes, with patients with significant symptoms improving the most across all domains. Utilization differed across classes, with the mixed symptom class receiving more PT and injections and significant symptom class receiving more surgeries and specialist visits.

Conclusions

Patients with LBP have distinct clinical symptom classes which could be utilized to stratify patients into groups based on risk of future disability. These symptom classes can also be used to provide estimates of the effectiveness of different interventions, further increasing the clinical utility of these classes in standard care.

Knowledge Mapping of International Research on Acupuncture for Chronic Pain: A Bibliometric Analysis

INTRODUCTION

With the wide acceptance of acupuncture, many papers and guidelines recommend that acupuncture is effective for chronic pain (CP). In this study, we applied bibliometric methods to analyze the current research situation of acupuncture intervention in CP, to gain insight into the current situation and future development trend of this field.

MATERIAL AND METHODS

Science Citation Index Expanded was searched for publications related to acupuncture for CP between 1900 and 2022. VOSviewer, CiteSpace and Thomson Data Analyzer were used to analyze the annual publication, authors and cited authors and their countries (regions) and institutions, journals and cited journals, cited references, co-occurrence keywords, burst keywords, and the relevant centrality.

RESULTS

A total of 1968 papers were retrieved, the annual publications have shown a rapid growth trend in the recent 20 years. The USA (708) and the Kyung Hee University (31) were the most productive country and institution, respectively, while the USA (0.37) and University of Maryland (0.13) had the highest centrality. MacPherson, Hugh published the most papers in this field (29), and Vickers, A J were the most influential author (289 times cited). Journal of Alternative and Complementary Medicine was the most productive journal (92), whereas PAIN was the most influential one (4743 times cited). Breivik, H's (2006) paper had the most citation count (3025), while Furlan's (2005) paper had the highest centrality (0.23). The research focuses in this field mainly include pain, electroacupuncture, Low back pain, Systematic review, Randomized controlled trial etc. Researchers are currently paying more attention to the psychological problems caused by CP.

CONCLUSION

The research of acupuncture for CP will be further expanded. International cooperation of this research field needs to be further strengthened. More high-quality designed trials need to be conducted.

A multi-center, double-blind, randomized parallel-group Phase IV study comparing the efficacy and safety of thiocolchicoside ointment versus placebo in patients with chronic mechanical low back pain and an acute muscle spasm

Objectives

This study aims to evaluate the efficacy and safety of thiocolchicoside (TCC) ointment treatment compared to placebo in patients with chronic mechanical low back pain (LBP) accompanied by acute muscle spasms.

Patients and methods

A total of 292 adult patients (106 males, 186 females; mean age: 38.5±11.2 years; range, 18 to 64 years) were randomized to TCC group (n=147) and placebo group (n=145) in 12 centers between March 2020 and March 2021. Eight patients from each group were excluded from the analysis. The primary endpoint was pressure pain threshold (PPT) on Day 3, which was measured using a pressure algometer. Secondary endpoints were PPT on Day 7, patient, and physician Visual Analog Scales-pain (VAS-pain) on Days 3 and 7, and safety.

Results

The PPT values on Day 3 was not significantly different between the treatment groups (p=0.701). Similarly, TCC and placebo group had similar VAS-pain scores over trial period (p=0.577 or higher for comparisons). Significantly higher PPT values and lower VAS-pain scores on Days 3 and 7 were observed in both groups (p<0.001 for all). In patients with a PPT value of ≥3.87, TCC arm had higher PPT on Day 3 compared to placebo (p=0.029). Three patients (two in the TCC arm and one in the placebo arm) discontinued the trial due to an adverse event.

Conclusion

Topical TCC can be an appropriate option in a subset of patients with mild chronic LBP accompanied by muscle spasms. In a subset of patients with milder pain intensity, topical TCC may improve pain earlier. The results of this trial are compatible with the treatment approaches used in daily practice.

Individualized Exercise in Chronic Non-Specific Low Back Pain: A Systematic Review with Meta-Analysis on the Effects of Exercise Alone or in Combination with Psychological Interventions on Pain and Disability

This systematic review, meta-analysis and meta-regression investigated the effects of individualized interventions, based on exercise alone or combined with psychological treatment, on pain intensity and disability in patients with chronic non-specific low-back-pain. Databases were searched up to January 31, 2022 to retrieve respective randomized controlled trials of individualized and/or personalized and/or stratified exercise interventions with or without psychological treatment compared to any control. Fifty-eight studies (n = 10084) were included. At short-term follow-up (12 weeks), low-certainty evidence for pain intensity (SMD -0.28 [95%CI -0.42 to -0.14]) and very low-certainty evidence for disability (-0.17 [-0.31 to -0.02]) indicates effects of individualized versus active exercises, and very low-certainty evidence for pain intensity (-0.40; [-0.58 to -0.22])), but not (low-certainty evidence) for disability (-0.18; [-0.22 to 0.01]) compared to passive controls. At long-term follow-up (1 year), moderate-certainty evidence for pain intensity (-0.14 [-0.22 to -0.07]) and disability (-0.20 [-0.30 to -0.10]) indicates effects versus passive controls. Sensitivity analyses indicates that the effects on pain, but not on disability (always short-term and versus active treatments) were robust. Pain reduction caused by individualized exercise treatments in combination with psychological interventions (in particular behavioral-cognitive therapies) (-0.28 [-0.42 to -0.14], low certainty) is of clinical importance. Certainty of evidence was downgraded mainly due to evidence of risk of bias, publication bias and inconsistency that could not be explained. Individualized exercise can treat pain and disability in chronic non-specific low-back-pain. The effects at short term are of clinical importance (relative differences versus active 38% and versus passive interventions 77%), especially in regard to the little extra effort to individualize exercise. Sub-group analysis suggests a combination of individualized exercise (especially motor-control based treatments) with behavioral therapy interventions to booster effects. PERSPECTIVE: The relative benefit of individualized exercise therapy on chronic low back pain compared to other active treatments is approximately 38% which is of clinical importance. Still, sustainability of effects (> 12 months) is doubtable. As individualization in exercise therapies is easy to implement, its use should be considered. PROSPERO REGISTRATION: CRD42021247331.

The importance of selecting the correct site to apply spinal manipulation when treating spinal pain: Myth or reality? A systematic review

The concept that spinal manipulation therapy (SMT) outcomes are optimized when the treatment is aimed at a clinically relevant joint is commonly assumed and central to teaching and clinical use (candidate sites). This systematic review investigated whether clinical effects are superior when this is the case compared to SMT applied elsewhere (non-candidate sites). Eligible study designs were randomized controlled trials that investigated the effect of spinal manipulation applied to candidate versus non-candidate sites for spinal pain. We obtained data from four different databases. Risk of bias was assessed using an adjusted Cochrane risk of bias tool, adding four items for study quality. We extracted between-group differences for any reported outcome or, when not reported, calculated effect sizes from the within-group changes. We compared outcomes for SMT applied at a 'relevant' site to SMT applied elsewhere. We prioritized methodologically robust studies when interpreting results. Ten studies, all of acceptable quality, were included that reported 33 between-group differences-five compared treatments within the same spinal region and five at different spinal regions. None of the nine studies with low or moderate risk of bias reported statistically significant between-group differences for any outcome. The tenth study reported a small effect on pain (1.2/10, 95%CI - 1.9 to - 0.5) but had a high risk of bias. None of the nine articles of low or moderate risk of bias and acceptable quality reported that "clinically-relevant" SMT has a superior outcome on any outcome compared to "not clinically-relevant" SMT. This finding contrasts with ideas held in educational programs and clinical practice that emphasize the importance of joint-specific application of SMT.

Clinical Effectiveness and Efficacy of Chiropractic Spinal Manipulation for Spine Pain

Spine pain is a highly prevalent condition affecting over 11% of the world's population. It is the single leading cause of activity limitation and ranks fourth in years lost to disability globally, representing a significant personal, social, and economic burden. For the vast majority of patients with back and neck pain, a specific pathology cannot be identified as the cause for their pain, which is then labeled as non-specific. In a growing proportion of these cases, pain persists beyond 3 months and is referred to as chronic primary back or neck pain. To decrease the global burden of spine pain, current data suggest that a conservative approach may be preferable. One of the conservative management options available is spinal manipulative therapy (SMT), the main intervention used by chiropractors and other manual therapists. The aim of this narrative review is to highlight the most relevant and up-to-date evidence on the effectiveness (as it compares to other interventions in more pragmatic settings) and efficacy (as it compares to inactive controls under highly controlled conditions) of SMT for the management of neck pain and low back pain. Additionally, a perspective on the current recommendations on SMT for spine pain and the needs for future research will be provided. In summary, SMT may be as effective as other recommended therapies for the management of non-specific and chronic primary spine pain, including standard medical care or physical therapy. Currently, SMT is recommended in combination with exercise for neck pain as part of a multimodal approach. It may also be recommended as a frontline intervention for low back pain. Despite some remaining discrepancies, current clinical practice guidelines almost universally recommend the use of SMT for spine pain. Due to the low quality of evidence, the efficacy of SMT compared with a placebo or no treatment remains uncertain. Therefore, future research is needed to clarify the specific effects of SMT to further validate this intervention. In addition, factors that predict these effects remain to be determined to target patients who are more likely to obtain positive outcomes from SMT.