Magnitude, response, and psychological determinants of placebo effects in chronic low-back pain: a randomised, double-blinded, controlled trial

Ecocebo: How the interaction between environment and drug effects may improve pharmacotherapy outcomes

This narrative review describes the research on the effects of the association between environmental context and medications, suggesting the benefit of specific design interventions in adjunction to pharmacotherapy. The literature on Evidence-Based Design (EBD) studies and Neuro-Architecture show how contact with light, nature, and specific physical features of urban and interior architecture may enhance the effects of analgesic, anxiolytics, and antidepressant drugs. This interaction mirrors those already known between psychedelics, drugs of abuse, and setting. Considering that the physical feature of space is a component of the complex placebo configuration, the aim is to highlight those elements of built or natural space that may help to improve drug response in terms of efficacy, tolerability, safety, and compliance. Ecocebo, the integration of design approaches such as EBD and Neuro-Architecture may thus contribute to a more efficient, cost-sensitive, and sustainable pharmacotherapy.

Investigating the hypoalgesic effects of spinal manipulative therapy using hidden pain conditioning and positive expectation in patients with chronic low back pain: protocol for a randomised controlled trial

INTRODUCTION

Placebo effects are responses capable of modulating pain and influencing treatment response. Two mechanisms are commonly related to placebo effects: expectations and conditioning. However, the research in this field is focused on laboratory studies with healthy participants. This study aims to identify whether a conditioning procedure with positive induced expectations about spinal manipulative therapy (SMT) will result in greater hypoalgesic effects in adults with chronic low back pain (CLBP) in a clinical trial design.

METHODS AND ANALYSIS

This trial will enrol 264 patients with non-specific CLBP, aged 18-60 years. Patients will undergo a calibration test to determine the thermal pain threshold for the hidden pain conditioning procedure. Afterward, they will be randomised to one of the three groups: hidden pain conditioning with positive induced expectations-group one (G1); positive expectations-group two (G2) and neutral expectations-group three (G3). Patients will receive instructions to manipulate the expectations. The pretreatment heat pain test will be performed before the SMT and after the intervention patients will undergo again the heat pain intensity test. However, only patients in G1 will receive hidden pain conditioning to reinforce the association between SMT and pain intensity reduction. All patients will undergo five sessions of SMT. The outcomes will be assessed immediately after the last session and at the 6 weeks and 3-month follow-ups. All statistical analyses will be conducted following intention-to-treat principles, and the treatment effects will be determined with linear mixed models.

ETHICS AND DISSEMINATION

The Federal University of São Carlos approved this research (Process n° 52359521.1.0000.5504). All participants will give written informed consent. Dissemination of the results will include publications in peer-reviewed journals and presentations at conferences. If positive expectations and classical conditioning improve outcomes, it may support the administration of such intervention.

TRIAL REGISTRATION NUMBER

NCT05202704.

Randomized controlled trial of suprascapular nerve blocks for subacute adhesive capsulitis

BACKGROUND

Shoulder pain and loss of function remain a therapeutic challenge in adhesive capsulitis. Suprascapular nerve blocks, a common treatment in adhesive capsulitis, are considered a safe and effective method for the resolution of pain and restoration of shoulder range of motion (ROM). To our knowledge, no data are available on the use of suprascapular nerve blocks in adhesive capsulitis in the subacute phase.

AIM

The aim of this study was to compare the efficacy of ultrasound-guided suprascapular nerve blocks versus saline injections for treating adhesive capsulitis in the subacute phase.

DESIGN

Randomized double-blinded controlled trial; level of evidence 2.

SETTING

Out-patient consultation of Physical and Rehabilitation Medicine in a general hospital.

POPULATION

Thirty-five patients with subacute adhesive capsulitis.

METHODS

Patients were randomly allocated to receive either 3 successive (1-week interval) ultrasound-guided suprascapular nerve blocks with ropivacaine 5 mL 2 mg/mL (intervention group) or ultrasound-guided injections of 5 mL sterile saline solution (NaCl 0.9%) (control group), at the floor of the suprascapular fossa. Primary outcome was shoulder function assessed by the Constant-Murley Score. Secondary outcomes were shoulder ROM and shoulder pain intensity. Assessments were performed before each injection and 4 weeks after the last injection.

RESULTS

A significant increase of Constant-Murley Score (P<0.001), increase of shoulder ROM (all directions: P<0.011) and decrease of pain (P<0.001), were observed over time in both study groups. However, no significant differences were observed between the intervention and the control group.

CONCLUSIONS

Three successive suprascapular nerve blocks did not provide a better outcome than saline injections on shoulder function, ROM, and pain in subacute adhesive capsulitis. These negative findings warrant some considerations on the natural history of adhesive capsulitis, as well as timing, type, and placebo effects of injections.

CLINICAL REHABILITATION IMPACT

The current place of suprascapular nerve blocks in the treatment strategy of adhesive capsulitis needs to be rediscussed.

Recruitment and retention for chronic pain clinical trials: a narrative review

Opioid misuse is at a crisis level. In response to this epidemic, the National Institutes of Health has funded $945 million in research through the Helping to End Addiction Long-term (HEAL) Pain Management Initiative, including funding to the Vanderbilt Recruitment Innovation Center (RIC) to strategize methods to catalyze participant recruitment. The RIC, recognizing the challenges presented to clinical researchers in recruiting individuals experiencing pain, conducted a review of evidence in the literature on successful participant recruitment methods for chronic pain trials, in preparation for supporting the HEAL Pain trials. Study design as it affects recruitment was reviewed, with issues such as sufficient sample size, impact of placebo, pain symptom instability, and cohort characterization being identified as problems. Potential solutions found in the literature include targeted electronic health record phenotyping, use of alternative study designs, and greater clinician education and involvement. For retention, the literature reports successful strategies that include maintaining a supportive staff, allowing virtual study visits, and providing treatment flexibility within the trial. Community input on study design to identify potential obstacles to recruitment and retention was found to help investigators avoid pitfalls and enhance trust, especially when recruiting underrepresented minority populations. Our report concludes with a description of generalizable resources the RIC has developed or adapted to enhance recruitment and retention in the HEAL Pain studies. These resources include, among others, a Recruitment and Retention Plan Template, a Competing Trials Tool, and MyCap, a mobile research application that interfaces with Research Electronic Data Capture (REDCap).

Who are the placebo responders? A cross-sectional cohort study for psychological determinants

ABSTRACT

A number of studies have demonstrated substantial individual differences in placebo effects. We aimed to identify individual psychological factors that potentially predicted the magnitude of placebo hypoalgesia and individual responsiveness. The Research Domain Criteria framework and a classical conditioning with suggestions paradigm were adopted as experimental models to study placebo phenotypes in a cohort of 397 chronic pain participants with a primary diagnosis of temporomandibular disorder (TMD) and 397 healthy control (HC) participants. The magnitude of placebo hypoalgesia was operationalized as the average difference in pain ratings between the placebo and control conditions. The individual placebo responsiveness was identified as the status of placebo responders and nonresponders based on a permutation test. We observed significant placebo effects in both TMD and HC participants. A greater level of emotional distress was a significant predictor of smaller magnitude (slope b = -0.07) and slower extinction rate (slope b = 0.51) of placebo effects in both TMD and HC participants. Greater reward seeking was linked to greater postconditioning expectations (ie, reinforced expectations) in TMD (slope b = 0.16), but there was no such a prediction in HC participants. These findings highlight that negative valence systems might play a role in impairing placebo effects, with a larger impact in chronic pain participants than in healthy participants, suggesting that individuals reporting emotional distress and maladaptive cognitive appraisals of pain may benefit less from placebo effects.

Cutoff criteria for the placebo response: a cluster and machine learning analysis of placebo analgesia

Computations of placebo effects are essential in randomized controlled trials (RCTs) for separating the specific effects of treatments from unspecific effects associated with the therapeutic intervention. Thus, the identification of placebo responders is important for testing the efficacy of treatments and drugs. The present study uses data from an experimental study on placebo analgesia to suggest a statistical procedure to separate placebo responders from nonresponders and suggests cutoff values for when responses to placebo treatment are large enough to be separated from reported symptom changes in a no-treatment condition. Unsupervised cluster analysis was used to classify responders and nonresponders, and logistic regression implemented in machine learning was used to obtain cutoff values for placebo analgesic responses. The results showed that placebo responders can be statistically separated from nonresponders by cluster analysis and machine learning classification, and this procedure is potentially useful in other fields for the identification of responders to a treatment.

Thirty Years of Neuroscientific Investigation of Placebo and Nocebo: The Interesting, the Good, and the Bad

Over the past 30 years there has been a surge of research on the placebo effect using a neuroscientific approach. The interesting aspects of this effort are related to the identification of several biological mechanisms of both the placebo and nocebo effects, the latter of which is defined as a negative placebo effect. Some important translational implications have emerged both in the setting of clinical trials and in routine medical practice. One of the principal contributions of neuroscience has been to draw the attention of the scientific and medical communities to the important role of psychobiological factors in therapeutic outcomes, be they drug related or not. Indeed, many biological mechanisms triggered by placebos and nocebos resemble those modulated by drugs, suggesting a possible interaction between psychological factors and drug action. Unfortunately, this new knowledge regarding placebos has the potential of being dangerously exploited by pseudoscience. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Patient Expectancy Does Not Predict Success or Failure of Thermal Neurotomy for Persistent Zygapophysial and Sacroiliac Joint Pain

OBJECTIVE

The placebo effect is important in determining the outcome of the treatment of pain for which expectancy and context are the main contributors. The variable success of thermal neurotomy spinal pain procedures is often seen as evidence of the placebo effect. Conversely, proponents of pain procedures explain poorer outcomes by technical procedure deficiencies, including inadequate diagnosis. This cohort study set out to determine whether patient expectancy is a contributing factor in the outcome of thermal neurotomy to the cervical, thoracic, and lumbar zygapophysial and sacroiliac joints.

DESIGN

This single-practitioner, single-site retrospective analysis of prospectively gathered cohort data of 549 patients evaluated the impact of patient preprocedure expectancy (rated on a simple 0-10 or 0-4 numerical rating scale) on outcomes in a large consecutive series of patients who had undergone thermal neurotomy treatment between 2009 and 2019. In addition, a portion of patients were asked to what extent they hoped for or desired a good outcome.

RESULTS

Successful pain relief (≥75% reduction from baseline) was not associated with a higher preprocedure expectancy than were failed procedures. Hope and desire demonstrated no impact on the positive or negative impact of the procedure.

CONCLUSIONS

Altogether, patient expectation of outcome, hope, and desire are not associated with the outcome of effective pain relief by thermal neurotomy that has been performed to the appropriate and commonly available technical standards. Further work is needed to determine the influence of patient expectation across a range of pain intervention modalities.

Management of facet joints osteoarthritis associated with chronic low back pain: A systematic review

INTRODUCTION

Facet joint injections (FJI) and medial branch blocks (MBB) can be employed for chronic low back pain (LBP) using different drugs such as corticosteroids, hyaluronic acid, sarapin and local anaesthetics. This systematic review compares the results of injections obtained with different compounds in the management LBP originating from facet joints.

METHODS

The present systematic review was conducted according to the PRISMA statement. The literature search was performed in October 2020. All the randomized clinical trials concerning injection treatments for chronic LBP. Drugs rather than steroids, hyaluronic acid, anaesthetics and sarapin were not considered, as well as those reporting outcomes from combined treatments. The Oswestry Disability Index (ODI) and the numeric rating scale (NRS) were retrieved.

RESULTS

Data from 587 patients were retrieved. The mean follow-up was 12.4 ± 10.5 months. The mean age was 51.3 ± 9.6 years old. 57% (335/587) of patients were women. Steroids promoted a reduction of NRS by 28% (P < 0.0001) and an improvement of the ODI by 13.2% (P = 0.005), and local anaesthetics produced an improvement of the ODI by 9.8% (P < 0.0001). Sarapin resulted in a reduction of NRS by 44% (P = 0.04) and an improvement the ODI by 14.9% (P = 0.004); sarapin combined with steroids promoted a reduction of NRS by 47% (P = 0.04) and an improvement of the ODI by 11.7% (P = 0.001).

CONCLUSION

Injections for chronic LBP deriving from facet joints osteoarthritis are encouraging, especially when considering MBB.

LEVEL OF EVIDENCE

I, systematic review of RCTs.

The Utility of Pain Scale to Assess Verifiable vs Non-Verifiable Pain in United States Emergency Departments

Introduction

We sought to examine the utility of self-reported pain scale by comparing emergency department (ED) triage pain scores of self-reported but non-verifiable painful conditions with those of verifiable painful conditions using a large, nationally representative sample.

Methods

We analyzed the National Hospital Ambulatory Medical Care Survey (NHAMCS) 2015. Verifiable painful conditions were identified based on the final diagnoses in the five included International Classification of Diseases 9th revision codes. Non-verifiable painful conditions were identified by the five main reasons for visit. Only adults 18 years of age or older were included. The primary outcome variable was the pain scale from 0 to 10 at triage. We performed descriptive and multivariate analyses to investigate the relationships between the pain scale and whether the painful condition was verifiable, controlling for patient characteristics.

Results

There were 55 million pain-related adult ED visits in 2015. The average pain scale was 6.49. For verifiable painful diagnoses, which were about 24% of the total visits, the average was 6.27, statistically significantly lower than that for non-verifiable painful conditions, 6.56. Even after controlling for the confounding of patient characteristics and comorbidities, verifiable painful diagnoses still presented less pain than those with non-verifiable painful complaints. Older age, female gender, and urban residents had significantly higher pain scores than their respective counterparts, controlling for other confounding factors. Psychiatric disorders were independently associated with higher pain scores by about a half point.

Conclusion

Self-reported pain scales obtained at ED triage likely have a larger psychological component than a physiological one. Close attention to clinical appropriateness and overall patient comfort are more likely to lead to better health outcomes and patient experiences than focusing on self-reported pain alone.

Placebos in chronic pain: evidence, theory, ethics, and use in clinical practice

Despite their ubiquitous presence, placebos and placebo effects retain an ambiguous and unsettling presence in biomedicine. Specifically focused on chronic pain, this review examines the effect of placebo treatment under three distinct frameworks: double blind, deception, and open label honestly prescribed. These specific conditions do not necessarily differentially modify placebo outcomes. Psychological, clinical, and neurological theories of placebo effects are scrutinized. In chronic pain, conscious expectation does not reliably predict placebo effects. A supportive patient-physician relationship may enhance placebo effects. This review highlights "predictive coding" and "bayesian brain" as emerging models derived from computational neurobiology that offer a unified framework to explain the heterogeneous evidence on placebos. These models invert the dogma of the brain as a stimulus driven organ to one in which perception relies heavily on learnt, top down, cortical predictions to infer the source of incoming sensory data. In predictive coding/bayesian brain, both chronic pain (significantly modulated by central sensitization) and its alleviation with placebo treatment are explicated as centrally encoded, mostly non-conscious, bayesian biases. The review then evaluates seven ways in which placebos are used in clinical practice and research and their bioethical implications. In this way, it shows that placebo effects are evidence based, clinically relevant, and potentially ethical tools for relieving chronic pain.

The neurobiological underpinnings of placebo and nocebo effects

The placebo effect, once considered only a nuisance in clinical research, is today a target of scientific inquiry that allows us understand how words, rituals and, more in general, the whole psychosocial context around the patient, affect the response to a treatment and the course of a disease. Today we are in a good position to study all these complex psychological factors by using a physiological and neuroscientific approach that uses modern neurobiological tools to probe different brain functions. Since a placebo is represented by the whole ritual of the therapeutic act, the main concept that has emerged today is that words and rituals may modulate the same biochemical pathways that are modulated by drugs. Most of our knowledge about these mechanisms comes from the field of pain, and represents a biomedical, psychological and philosophical enterprise that is changing the way we approach and interpret medicine, psychology and human biology. If on the one hand we know some of the mechanisms of drug action in the central nervous system, on the other we can now understand how the clinician-patient interaction may affect different physiological functions. In fact, the placebo effect and the therapist-patient relationship can be approached by using the same biochemical, cellular and physiological tools of the materia medica. This represents an epochal transition, in which the distinction between drugs and words is progressively getting thinner, and which helps us overcome the old dichotomy between psychology and biology.

Influence of placebo analgesia in pharmacological treatment of pain

Placebo effects are relevant to routine clinical practice, even if no traditional placebo is given. The healthcare encounter is often rich in factors that may affect both placebo and nocebo components of care, therefore, an opportunity exists to target elements of this encounter to enhance clinical effectiveness. This review will outline the contemporary conceptualizations of placebo and the mechanisms of placebo effects. Specifically, how to harness these placebo effects in clinical practice. Currently, these include optimizing the therapeutic context, shaping of expectations, assessing belief structures and framing information delivery, utilization of conditioning regimes to augment drug response or reduce overall drug dosing and the potential integration of traditional placebos with scientifically proven treatments to augment care.

An Exploration of Knowledge and Attitudes of Medical Students and Rheumatologists to Placebo and Nocebo Effects: Threshold Concepts in Clinical Practice

INTRODUCTION

Understanding placebo and nocebo responses (context/meaning effects [CMEs]) is fundamental to physician agency. Specific instruction in CMEs is often lacking in medical education. Patient-practitioner interactions may challenge medical students' understanding of biomedical causality and the nexus between this, practical ethics and professionalism across various conceptual and applied aspects of CMEs. This study compared the corpus of knowledge and phronesis related to CMEs between Australian graduate medical students and rheumatologists to gain a sophisticated understanding of this relationship to inform curriculum development.

METHOD

In 2013 and 2014, the authors surveyed third-year medical students undertaking a graduate programme in an Australian medical school and Australian rheumatologists to ascertain their understanding of placebo and nocebo responses. The survey ascertained (1) the alignment of the respondents' understanding of CMEs with accepted facts and concepts; (2) opinions on the ethical status of CMEs; and (3) responses to 2 scenarios designed to explore matters of biomedical causality, practical ethics and professionalism.

RESULTS

There were 88 completed surveys returned, 53 rheumatologists and 35 students. Similar proportions within each group identified CMEs, with most (n = 79/88 [89.8%]) correctly recognising a placebo (rheumatologists: 50 [94.3%], students: 29 [82.9%]) and approximately three-quarters (n = 65/88 [73.9%]) correctly recognising nocebo effects (rheumatologists: 39 [73.6%], students: 26 [74.3%]). Statistically significant differences between practitioners and students were observed in relation to the following: placebo responders and placebo responsiveness; placebos as a 'diagnostic tool'; placebos usage in clinical practice and research, and nocebo effects.

CONCLUSIONS

Physicians require an awareness of CMEs and the fact that they arise from and influence the effective agency of health care professionals. Curricular emphasis is needed to permit an honest assessment of the components that influence when, how and why patient outcomes arise, and how one's agency might have neutral or negative effects but could be inclined towards positive and away from negative patient outcomes.