Nocebo effect in refractory partial epilepsy during pre-surgical monitoring: Systematic review and meta-analysis of placebo-controlled clinical trials

The present and future of seizure detection, prediction, and forecasting with machine learning, including the future impact on clinical trials

Seizures have a profound impact on quality of life and mortality, in part because they can be challenging both to detect and forecast. Seizure detection relies upon accurately differentiating transient neurological symptoms caused by abnormal epileptiform activity from similar symptoms with different causes. Seizure forecasting aims to identify when a person has a high or low likelihood of seizure, which is related to seizure prediction. Machine learning and artificial intelligence are data-driven techniques integrated with neurodiagnostic monitoring technologies that attempt to accomplish both of those tasks. In this narrative review, we describe both the existing software and hardware approaches for seizure detection and forecasting, as well as the concepts for how to evaluate the performance of new technologies for future application in clinical practice. These technologies include long-term monitoring both with and without electroencephalography (EEG) that report very high sensitivity as well as reduced false positive detections. In addition, we describe the implications of seizure detection and forecasting upon the evaluation of novel treatments for seizures within clinical trials. Based on these existing data, long-term seizure detection and forecasting with machine learning and artificial intelligence could fundamentally change the clinical care of people with seizures, but there are multiple validation steps necessary to rigorously demonstrate their benefits and costs, relative to the current standard.

Placebo response in patients with Dravet syndrome: Post-hoc analysis of two clinical trials

OBJECTIVE

Dravet syndrome is a rare, early childhood-onset epileptic and developmental encephalopathy. Responses to placebo in clinical trials for epilepsy therapies range widely, but factors influencing placebo response remain poorly understood. This study explored placebo response and its effects on safety, efficacy, and quality of life outcomes in patients with Dravet syndrome.

METHODS

We performed exploratory post-hoc analyses of pooled data from placebo-treated patients from the GWPCARE 1B and GWPCARE 2 randomized controlled phase III trials, comparing cannabidiol and matched placebo in 2-18 year old Dravet syndrome patients. All patients had ≥4 convulsive seizures during a baseline period of 4 weeks.

RESULTS

124 Dravet syndrome-treated patients were included in the analysis (2-5 years: n = 35; 6-12 years: n = 52; 13-18 years: n = 37). Convulsive seizures were experienced by all placebo group patients at all timepoints, with decreased median convulsive seizure frequency during the treatment period versus baseline; the number of convulsive seizure-free days was similar to baseline. Convulsive seizure frequency had a nominally significant positive correlation with age and a nominally significant negative correlation with body mass index. Most placebo-treated patients experienced a treatment-emergent adverse event; however, most resolved quickly, and serious adverse events were infrequent. Placebo treatment had very little effect on reported Caregiver Global Impression of Change outcomes versus baseline.

INTERPRETATION

Placebo had little impact on convulsive seizure-free days and Caregiver Global Impression of Change versus baseline, suggesting that these metrics may help differentiate placebo and active treatment effects in future studies. However, future research should further assess placebo responses to confirm these results.

Lack of association between generic brittleness and neuropsychiatric measures in patients with epilepsy

PURPOSE

In a prior bioequivalence study, generic brittle (GB) patients with epilepsy who were considered at risk of worsened seizures or drug side effects from switching antiepileptic drug (AED) formulations demonstrated no significant difference in their drug levels when switched between a brand and generic AED. An alternative basis for being GB may relate to having a personality or mindset that predisposes to poor outcomes from a formulation switch. The objective of this study was to explore whether GB patients with epilepsy could be differentiated from not GB patients based on standardized measures of personality, mood, outlook, and beliefs.

METHODS

This was an exploratory, observational, case-control, non-therapeutic study in patients with epilepsy. Patient interviews were conducted, and histories were collected, yielding each patient (n = 148) to be determined as GB or not GB. Eight neuropsychiatry tests were administered to n = 127 of these patients. Tests included Neuroticism Extraversion Openness Personality Inventory 3 (NEO-PI 3), Life Orientation Test-Revised (LOT-R), Quality of Life in Epilepsy Inventory-89 (QOLIE-89), Adverse Childhood Experiences Score (ACE), Physical Symptoms Questionnaire or Patient Health Questionnaire-15 (PHQ-15), Beck Depression Inventory II (BDI-II), Beck Anxiety Inventory (BAI), and the Beliefs About Medicines Questionnaire Epilepsy (BMQ-Epilepsy). A total of 23 Chi squared analyses, along with logistical regression, were performed to assess which tests and sub-elements associated with GB status.

RESULTS

None of the neuropsychiatry tests or their sub-elements differentiated GB patients from not GB patients. Results implicate that standardized measures of personality, mood, outlook, and beliefs about their healthcare do not differ between GB and not GB patients with epilepsy, possibly because generic brittleness is caused by factors that neuropsychiatry tests do not measure.

CONCLUSIONS

We hypothesized that being GB may relate to having a personality or mindset that predisposes patients to attributing poor outcomes to a formulation switch. However, findings here in patients with epilepsy did not uncover neuropsychiatric factors that predict which patients were GB and which were not GB.

Maximizing placebo response in neurological clinical practice

The placebo effect is a widely recognized phenomenon in clinical research, with a negative perception that it could hide the "true" drug effect. In clinical care its positive potential to increase known drug effects has been neglected for too long. The placebo and nocebo responses have been described in many neurologic disorders such as Parkinson's, Huntington's and Alzheimer's diseases, restless leg syndrome, tics, essential tremor, dystonia, functional movement disorders, neuropathic pain, headaches, migraine, amyotrophic lateral sclerosis, myasthenia gravis, chronic inflammatory demyelinating polyneuropathy, multiple sclerosis and epilepsy. Knowledge regarding placebo mechanisms and their consequences on clinical outcome have greatly improved over the last two decades. This evolution has led to reconsiderations of the importance of placebo response in the clinic and has given several clues on how to improve it in daily practice. In this chapter, we first illustrate "why," e.g. the reasons (relevance to clinical practice, help in differential diagnosis/treatment of psychogenic movements, clinical impact, proven neurobiological grounds, health economic potential), and "how," e.g. the means (increase patients' knowledge, increase learning, improve patient-doctor relationship, increase Hawthorne effect, increase positive/decrease negative expectations (the Rosenthal effect), personalize placebo response), the placebo should be maximized (and nocebo avoided) in neurological clinical practice. Future studies regarding more specific neurobiological mechanisms will allow a finer tuning of placebo response in clinical practice. The use of placebo in clinical practice raises ethical issues, and a recent expert consensus regarding placebo use in the clinic is a first step to future guidelines necessary to this field.

Nocebo and lessebo effects

The power of placebos is commonly associated with the placebo effect. In contrast, detrimental effects related to the use of a placebo are little studied and less well recognized. This chapter covers the nocebo and lessebo effects defined, respectively, as expectation of harm in the form of adverse events in a placebo arm and reduction of therapeutic benefit due to the uncertainty of being allocated to placebo. The lessebo effect is a more recent concept and has been described only in depression, schizophrenia and Parkinson's disease. The nocebo response was evaluated in many neurological diseases, including epilepsy, multiple sclerosis, Parkinson's disease, Alzheimer's disease, restless leg syndrome, among others. Meta-analyses of randomized controlled trials in these conditions reveal a significant variability of the magnitude of the nocebo response and that factors related to study design, study participants or neurological disease can be associated with a nocebo response, although with the opposing findings across conditions. The knowledge about neurobiological mechanisms of the nocebo effect is poor for neurological diseases, and most of the information has been generated in pain. Functional neuroimaging suggests the existence of a distinct network for the anticipation and the experience of a hyperalgesia nocebo response. Different types of neurotransmitters have been involved, including cholecystokinin, dopamine and opioids. Recognizing the potential impact of nocebo and lessebo effects, mitigating strategies are in development with application to clinical research and clinical practice, such as a contextualized informed consent process, alternative study designs and enhancement of patient-physician communication.

Placebo and nocebo phenomena in anti- CGRP monoclonal antibody trials for migraine prevention: a meta-analysis

High placebo and low nocebo phenomena mirror high positive expectations for a novel treatment, among other reasons. In a meta-analysis aimed to identify placebo and nocebo phenomena in the placebo-controlled randomized trials (RCTs) with the monoclonal antibodies targeting the calcitonin gene-related peptide pathway (anti-CGRP mAbs) all the placebo-treated patients were pooled and compared with the placebo-treated patients in RCTs with topiramate and onabotulinum toxin A (OBTA). In episodic migraine (EM), the proportion of placebo-treated patients who achieved the 50% responder rate (placebo) was 32.7% (95% CI 28.6%-37.0%) in anti-CGRP mAbs vs. 24.4% (95% CI 20.5%-28.5%) in topiramate trials. The proportion of dropouts due to adverse events in placebo-treated patients (nocebo) was 1.9% (95% CI 1.4%-2.6%) in anti-CGRP mAbs vs. 9.9% (95% CI 7.7%-12.3%) in topiramate RCTs. In chronic migraine (CM), the placebo 50% responder rate was 23.6% (95% CI 11.2%-38.8%) in anti-CGRP mAbs RCTs vs. 36.4% (95% CI 32.6%-39.3%) in RCTs with OBTA. The nocebo dropout in anti-CGRP mAbs and OBTA RCTs was 1.4% (95% CI 0.8%-2.1%) and 0.9 (95% CI 0.3%-1.7%), respectively. The stronger placebo and weaker nocebo phenomena in RCTs with anti-CGRP mAbs vs. those with topiramate in the prophylaxis of EM, may decisively determine anti-CGRP mAbs treatment success. No differences were detected between the anti-CGRP mAbs and OBTA in the treatment of CM.

Nocebo in Biosimilars and Generics in Neurology: A Systematic Review

Background: Nocebo refers to adverse events related to patients’ negative expectations and previous experiences, mediated by several neurobiological pathways within the brain. It is common among neurological patients and affects adherence and treatment outcomes, representing a real clinical challenge.

Methods: We conducted a systematic search based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines in MEDLINE database, using several keywords for studies that can be processed to investigate the magnitude of nocebo in generics and biosimilars used in the most common neurological diseases. The aim was to estimate its size and suggest strategies to minimize its prevalence in clinical trials and practice.

Results: Of a total of 2,606 identified articles, after criteria-based selection, 35 studies were included for analysis. Overall, there was vast heterogeneity across the studies concerning population, study design, and outcomes. Nocebo response could be estimated only in one double-blind randomized trial of generic glatiramer acetate in relapsing remitting multiple sclerosis that included a placebo arm. In this trial, no significant differences observed between the three arms (innovator, bioequivalent, and placebo) in favorable and unfavorable outcomes. In the open-label phase of the trial, an increased withdrawal rate was recorded in patients switched from placebo to bioequivalent (8.4%) that may be related to nocebo. In other open-label and real-world studies evaluating biosimilars or generics for brain disorders, a similar indirect nocebo effect is assuming by several investigators. Also, knowledge gaps between health-care providers and patients exist towards generics and biosimilars.

Conclusions: Despite its presence, the true burden of the nocebo response and effect cannot be accurately estimated in existing studies with generics and biosimilars in neurological diseases. Targeted strategies for clinical trials’ design are needed in order to measure the exact nocebo’s size.

Nocebo effect in myasthenia gravis: systematic review and meta-analysis of placebo-controlled clinical trials

Nocebo refers to the adverse events (AEs) experienced when taking a placebo drug and is believed to be a centrally mediated process. We sought to examine the AEs following placebo administration in Randomised Controlled Trials (RCTs) for Myasthenia Gravis (MG) patients. A systematic literature search was performed on Medline and Web of Science for RCTs for MG pharmacological treatments. We assessed the number of placebo-treated patients reporting at least one AE and the number of dropouts because of AEs. Data were extracted from six RCTs fulfilling the search criteria. Four out of five placebo-treated participants (80.1%) reported at least one AE and one in 40 (2.4%) discontinued placebo treatment because of AE. All patients participating in the MG trials reported similar AEs independent of the study arm to which they belonged (placebo or active treatment). This meta-analysis demonstrates a low nocebo dropout rate in MG compared to central nervous system disorders.

Nocebo in cerebellar ataxia: A systematic review and meta-analysis of placebo-controlled clinical trials

INTRODUCTION

Nocebo, the negative counterpart of the placebo phenomenon results in the induction of adverse events (AEs) following the administration of an inert substance. Nocebo has been demonstrated to be associated with low treatment compliance in clinical trials, thus affecting treatment outcomes. This study sought to determine the prevalence of nocebo in cerebellar ataxia.

METHODS

A systematic literature search was conducted on Pubmed for randomized controlled trials (RCTs) for cerebellar ataxia treatments. The number of drug-related AEs and the number of withdrawals due to drug intolerance in the placebo group were statistically analysed.

RESULTS

The literature search identified 214 studies, of which 6 studies fulfilled the inclusion criteria. Approximately 1 in 20 (4.8%) placebo-treated patients withdrew treatment due to AEs and approximately 1 in 7 (13.8%) placebo-treated participants reported at least one AE. Participants in cerebellar ataxia trials reported similar AEs across both treatment groups (active and placebo).

CONCLUSION

Our results demonstrate that the nocebo effect in cerebellar ataxia is amongst the lowest in neurological diseases.

Safety, Tolerability, and Nocebo Phenomena During Transcranial Magnetic Stimulation: A Systematic Review and Meta-Analysis of Placebo-Controlled Clinical Trials

BACKGROUND

The methodology used for the application of repetitive transcranial magnetic stimulation (TMS) is such that it may induce a placebo effect. Respectively, adverse events (AEs) can occur when using a placebo, a phenomenon called nocebo. The primary aim of our meta-analysis is to establish the nocebo phenomena during TMS. Safety and tolerability of TMS were also studied.

METHODS

After a systematic Medline search for TMS randomized controlled trials (RCTs), we assessed the number of patients reporting at least one AE and the number of discontinuations because of AE in active and sham TMS groups.

RESULTS

Data were extracted from 93 RCTs. The overall pooled estimate of active TMS and placebo treated patients who discontinued treatment because of AEs was 2.5% (95% CI 1.9%-3.2%) and 2.7% (95% CI 2.0%-3.5%), respectively. The pooled estimate of active TMS and placebo treated patients experiencing at least one AE was 29.3% (95% CI 19.0%-22.6%) and 13.6% (95% CI 11.6%-15.8%), respectively, suggesting that the odds of experiencing an AE is 2.60 times higher (95% CI 1.75-3.86) in the active treatment group compared to placebo (p < 0.00001). The most common AE was headache, followed by dizziness. Secondary meta-analyses in depression and psychotic disorders showed that the odds of experiencing an AE is 3.98 times higher (95% CI 2.14-7.40) and 2.93 times higher (95% CI 1.41-6.07), respectively, in the active treatment groups compared to placebo.

CONCLUSIONS

TMS is a safe and well-tolerated intervention. Nocebo phenomena do occur during TMS treatment and should be acknowledged during clinical trial design and daily clinical practice.

Exploring generic brittleness and the demographic factors for its susceptibility in patients with epilepsy

PURPOSE

The purpose of this study was to provide an algorithm for generic brittleness and to elucidate the demographic factors that anticipate generic brittleness for patients with epilepsy.

METHODS

This exploratory, observational, and nontherapeutic study was conducted in patients with epilepsy who were routinely followed at the University of Maryland epilepsy outpatient clinic in Baltimore, Maryland. Patients were taking at least one antiepileptic drug (AED) for treatment of epilepsy. Based on patient interview and medical history, 12 demographic factors were collected. Each patient was assessed to be either generic brittle (GB) or not GB. Demographic factors were subjected to binary logistical regression and other statistical tests, to elucidate determinants of GB status.

RESULTS

N = 148 patients completed the study. An algorithm to define whether a patient was GB or not GB was devised. The two elements that defined GB status are as follows: patient opinion about generics and (if needed) whether patients were currently taking brand or generic of their most problematic AED. About 40% of patients were GB. From binary logistical regression, two demographic factors that contributed to patients being GB were whether a patient was currently taking a problem AED and total number of current medications for a patient, with odds ratios of 4.06 (95% confidence interval [CI] from 1.53 to 10.81) and 1.10 (95% CI from 1.003 to 1.21), respectively. Of the patients on a problem AED, 46.9% were GB, while only 18.2% of patients not currently on a problem AED were GB. The total number of current medications ranged from 1 to 22, with mode of four medications. From regression, for each additional medication that a patient took, the odds of being GB increased 1.10-fold. Although patient seizure and adverse event history was not employed to define GB status, being GB was associated with less seizure control and greater adverse events.

CONCLUSIONS

An algorithm for generic brittleness was derived, and about 40% of patients were GB, usually due to prior history of a switch problem. Two demographic factors favored patients being GB: whether the patient was currently taking a problem AED and the total number of current medications.

Rapid overview of systematic reviews of nocebo effects reported by patients taking placebos in clinical trials

Background

Trial participants in placebo groups report experiencing adverse events (AEs). Existing systematic reviews have not been synthesized, leaving questions about why these events occur as well as their prevalence across different conditions unanswered.

Objectives

To synthesize the evidence of prevalence of AEs in trial placebo groups across different conditions.

To compare AEs in trial placebo groups with AEs reported in untreated groups within a subset of randomized trials.

Search methods

We searched PubMed for records with the word “nocebo” in the title and “systematic” in any field. We also contacted experts and hand-searched references of included studies.

Study eligibility

We included any systematic review of randomized trials where nocebo effects were reported. We excluded systematic reviews of non-randomized studies.

Participants and interventions

We included studies in any disease area.

Study appraisal and synthesis methods

We appraised the quality of the studies using a shortened version of the Assessment of Multiple Systematic Reviews tool (AMSTAR) tool. We reported medians and interquartile ranges (IQRs) of AEs. Among the trials within the review that included untreated groups, we compared the prevalence of AEs in untreated groups with the prevalence of AEs in placebo groups.

Results

We identified 20 systematic reviews. These included 1271 randomized trials and 250,726 placebo-treated patients. The median prevalence of AEs in trial placebo groups was 49.1% (IQR 25.7–64.4%). The median rate of dropouts due to AEs was 5% (IQR 2.28–8.4%). Within the 15 of trials that reported AEs in untreated groups, we found that the AE rate in placebo groups (6.51%) was higher than that reported in untreated groups (4.25%).

Limitations

This study was limited by the quality of included reviews and the small number of trials that included untreated groups.

Conclusions and implications of key findings

AEs in trial placebo groups are common and cannot be attributed entirely to natural history. Trial methodologies that reduce AEs in placebo groups while satisfying the requirement of informed consent should be developed and implemented.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-3042-4) contains supplementary material, which is available to authorized users.

Nocebo Effect in Menière's Disease: A Meta-analysis of Placebo-controlled Randomized Controlled Trials

OBJECTIVE

To estimate the frequency and strength of nocebo effects in trials for Menière disease (MD).

DATA SOURCES

A literature search was conducted in PUBMED. The search terms we used were " Menière or Menière's," "treatment," and "placebo." Limitations included article type to be Clinical Trial or Randomized Controlled Trial, text availability to be Full text, Species to be Humans and Language to be English.

STUDY SELECTION

We included placebo-controlled pharmaceutical RCTs that referred specifically to MD and recruited at least 10 adults in each arm. We excluded those studies with JADAD score ≤3.

DATA EXTRACTION

Thirty-six articles were screened identifying 12 eligible studies. Studies were included after consensus of both authors.

DATA SYNTHESIS

The meta-analysis was conducted using the RevMan programme as suggested by the Cochrane Collaboration Group. Data were analyzed using a random effects model.

CONCLUSION

Nocebo is an important confounding factor of the reported AEs in RCTs for treatment of MD and subsequently in the clinical practice. The pooled estimate of the percentage of placebo-treated patients with at least one AE was 42.3% (95% CI 8.1% to 16.3%), in comparison to 53.8% (95% CI 48.0% to 59.5%) for active drug-treated patients. Reporting of RCTs in MD is suboptimal and we recommend authors to endorse the CONSORT checklist.

A multi-dataset time-reversal approach to clinical trial placebo response and the relationship to natural variability in epilepsy

PURPOSE

Clinical epilepsy drug trials have been measuring increasingly high placebo response rates, up to 40%. This study was designed to examine the relationship between the natural variability in epilepsy, and the placebo response seen in trials. We tested the hypothesis that 'reversing' trial direction, with the baseline period as the treatment observation phase, would reveal effects of natural variability.

METHOD

Clinical trial simulations were run with time running forward and in reverse. Data sources were: SeizureTracker.com (patient reported diaries), a randomized sham-controlled TMS trial, and chronically implanted intracranial EEG electrodes. Outcomes were 50%-responder rates (RR50) and median percentage change (MPC).

RESULTS

The RR50 results showed evidence that temporal reversal does not prevent large responder rates across datasets. The MPC results negative in the TMS dataset, and positive in the other two.

CONCLUSIONS

Typical RR50s of clinical trials can be reproduced using the natural variability of epilepsy as a substrate across multiple datasets. Therefore, the placebo response in epilepsy clinical trials may be attributable almost entirely to this variability, rather than the "placebo effect".

Minimizing nocebo effect: Pragmatic approach

The nocebo effect, the inverse of the placebo effect, is a well-established phenomenon, yet under-appreciated. It refers to nonpharmacological, harmful, or undesirable effects occurring after active or inactive therapy. The frequency of adverse events can dramatically increase by informing patients about the possible side effects of the treatment, and by negative expectations on the part of the patient. Patients who were told that they might experience sexual side effects after treatment with β-blocker drugs reported these symptoms between three and four times more often than patients in a control group who were not informed about these symptoms. Nocebo effect has been reported in several neurological diseases such as migraine, epilepsy, multiple sclerosis, Parkinson's disease and neuropathic pain, and in patients with depression. The investigation of the biological and theoretical underpinning of the nocebo phenomenon is at an early stage, and more research is required. Physicians need to be aware of the influence of nocebo phenomenon and be able to recognize it and minimize its effects.