Adverse events of placebo-treated, drug-resistant, focal epileptic patients in randomized controlled trials: a systematic review

Re-evaluating the placebo response in recent canine dietary epilepsy trials

The placebo response is a common phenomenon. Limited evidence is available about its magnitude in canine epilepsy trials, even though it can significantly influence the efficacy evaluation of new treatments. It was hypothesised that the placebo response is diminished when epilepsy trials are conducted in a prospective crossover design. Seizure data spanning six months from three previous multicenter epilepsy studies were analysed. The monthly seizure frequency of 60 dogs diagnosed with idiopathic epilepsy was calculated, comparing baseline data with placebo treatment. Furthermore, differentiation was made between dogs randomised to the placebo group early (Phase 1: first 3 months) or later during the study (Phase 2: second 3 months).The analysis did not reveal any placebo response in terms of monthly seizure frequency. Instead, an increase was noted during the placebo treatment period, with a mean of 2.95 seizures per month compared to 2.30 seizures per month before study entry (p = 0.0378). Additionally, a notable phase effect was observed. Dogs receiving the placebo in the second study phase exhibited a significant increase in monthly seizure frequency compared to baseline (p = 0.0036). Conversely, no significant difference from baseline was observed for dogs receiving the placebo in the first study phase. These findings underscore the considerable variability in placebo responses observed in trials for canine epilepsy, contrasting with previous limited data. The identified phase effect should be carefully considered in the design and evaluation of canine epilepsy trials to ensure a more accurate assessment of efficacy for new treatments.

Quantifying and controlling the impact of regression to the mean on randomized controlled trials in epilepsy

OBJECTIVE

Randomized controlled trials (RCTs) in epilepsy for drug treatments are plagued by high costs. One potential remedy is to reduce placebo response via better control over regression to the mean (RTM). Here, RTM represents an initial observed seizure rate higher than the long-term average, which gradually settles closer to the average, resulting in apparent response to treatment. This study used simulation to clarify the relationship between eligibility criteria and RTM.

METHODS

Using a statistically realistic seizure diary simulator, the impact of RTM on placebo response and trial efficacy was explored by varying eligibility criteria for a traditional treatment phase II/III RCT for drug-resistant epilepsy.

RESULTS

When the baseline period was included in the eligibility criteria, increasingly larger fractions of RTM were observed (25%-47% vs. 23%-25%). Higher fractions of RTM corresponded with higher expected placebo responses (50% responder rate [RR50]: 2%-9% vs. 0%-8%) and lower statistical efficacy (RR50: 47%-67% vs. 47%-81%). The exclusion of baseline from eligibility criteria was shown to decrease the number of patients needed by roughly 30%.

SIGNIFICANCE

The manipulation of eligibility criteria for RCTs has a predictable and important impact on RTM, and therefore on placebo response; the difference between drug and placebo was more easily detected. This in turn impacts trial efficacy and therefore cost. This study found dramatic improvements in efficacy and cost when baseline was not included in eligibility.

Does the presence of a specialist doctor reduce the burden of disease in people with epilepsy in low-resource settings? A comparison of two epilepsy clinics in rural Tanzania

BACKGROUND

With an estimated lifetime prevalence of epilepsy of 7.6 per 1,000 people, epilepsy represents one of the most common neurological disorders worldwide, with the majority of people with epilepsy (PWE) living in low-income and middle-income countries (LMICs). Adequately treated, up to 70 % of PWE will become seizure-free, however, as many as 85% of PWE worldwide, mostly from LMICs, do not receive adequate treatment.

OBJECTIVE

To assess the impact of the presence of a neurologist on the management of PWE in Tanzania.

METHODS

Two epilepsy clinics in rural Tanzania, one continuously attended by a neurologist, and one mainly attended by nurses with training in epilepsy and supervised intermittently by specialist doctors (neurologists/psychiatrists) were comparatively analyzed by multivariable linear and logistic regression models with regard to the outcome parameters seizure frequency, the occurrence of side effects of antiepileptic medication and days lost after a seizure.

RESULTS

The presence of a neurologist significantly reduced the mean number of seizures patients experienced per month by 4.49 seizures (p < 0.01) while leading to an increase in the occurrence of reported side effects (OR: 2.15, p = 0.02).

CONCLUSION

The presence of a neurologist may play a substantial role in reducing the burden of the disease of PWE in LMICs. Hence, specialist training should be encouraged, and relevant context-specific infrastructure established.

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.

A Phase 2 Randomized Controlled Trial of the Efficacy and Safety of Cannabidivarin as Add-on Therapy in Participants with Inadequately Controlled Focal Seizures

Objective: We assessed the efficacy, safety, and tolerability of cannabidivarin (CBDV) as add-on therapy in adults with inadequately controlled focal seizures. Materials and Methods: One hundred and sixty-two participants (CBDV n=81; placebo n=81) were enrolled. After a 4-week baseline, participants titrated from 400 to 800 mg CBDV twice daily (b.i.d.) (or placebo) over 2 weeks, followed by 6 weeks stable dosing (at 800 mg b.i.d.) and a 12-day taper period. The primary endpoint was the change from baseline in focal seizure frequency during the 8-week treatment period. Secondary endpoints included additional efficacy measures relating to seizures, physician- and participant-reported outcomes, change in the use of rescue medication, cognitive assessments, and safety. Results: Median baseline focal seizure frequencies were 17-18 per 28 days in both groups, and similar reductions in frequency were observed in the CBDV (40.5%) and placebo (37.7%) groups during the treatment period (treatment ratio [% reduction] CBDV/placebo: 0.95 [4.6]; confidence interval: 0.78-1.17 [-16.7 to 21.9]; p=0.648). There were no differences between the CBDV and placebo groups for any seizure subtype. There were no significant treatment differences between CBDV and placebo groups for any of the secondary efficacy outcome measures. Overall, 59 (72.8%) of participants in the CBDV group and 39 (48.1%) in the placebo group had ≥1 treatment-emergent adverse event (AE); the 3 most common were diarrhea, nausea, and somnolence. The incidence of serious AEs was low (3.7% in the CBDV group vs. 1.2% in the placebo group). There was little or no effect of CBDV on vital signs, physical examination, or electrocardiogram findings. Elevations in serum transaminases (alanine aminotransferase or aspartate aminotransferase) to levels >3×upper limit of normal occurred in three participants taking CBDV (two discontinued as a result) and one taking placebo; however, none met the criteria for potential Hy's Law cases. Conclusion: It is likely the 40.5% seizure reduction with CBDV represents an appropriate pharmacological response in this population with focal seizures. The placebo response was, however, high, which may reflect the participants' expectations of CBDV, and a treatment difference from placebo was not observed. CBDV was generally well tolerated. Clinical Trial Registration number: NCT02365610.

Critical Appraisal of Cenobamate as Adjunctive Treatment of Focal Seizures in Adults

Cenobamate (CNB) is the latest antiseizure medication (ASM) authorized for the treatment of focal-onset seizures in adults. Although the precise mechanism of action of CNB is not yet fully understood, this drug inhibits the persistent, rather than transient, voltage-gated sodium channel currents and is a positive allosteric modulator of synaptic and extrasynaptic GABA_A receptors, differently from benzodiazepines. CNB has a non-linear pharmacokinetic with a terminal half-life range of about 50/60 hours within the therapeutic dose range, which allows once daily administration. Cenobamate inhibits cytochrome P450 (CYP) 2C19 and induces CYP3A4 and 2B6, and hence can potentially interact with ASMs (eg, phenytoin, carbamazepine and clobazam) and no-ASMs drugs. In two randomized, double-blind, placebo-controlled trials in patients with focal epilepsies, CNB has shown a particularly good efficacy with a rate of seizure freedom of about 20% during the maintenance period in participants treated with the dose of 400 mg/day. The most common treatment-emergent adverse effects include central nervous system-related symptoms, like dizziness, diplopia, somnolence, and gait disturbances. Safety issues of particular interest are severe skin reactions (drug reaction with eosinophilia and systemic symptoms) and QT shortening, which contraindicates its use in subjects with familial short QT syndrome or in combination with other QT-shortening drugs. The recommended starting dose is 12.5 mg/day, which can be gradually titrated to the target dose (200 mg/day) and further increased up to 400 mg/day. There are several aspects of CNB that need to be still addressed, including the long-term efficacy and the efficacy in patients with generalized seizures. Ongoing studies will clarify these issues. The clinical relevance of the peculiar pharmacokinetics and the pattern of drug-drug interactions also require further investigation.

Safinamide in neurological disorders and beyond: Evidence from preclinical and clinical studies

The discovery and development of safinamide, an alpha-aminoamide, has been a valuable addition to the existing clinical management of Parkinson's disease (PD). The journey of safinamide dates back to the year 1983, when an alpha-aminoamide called milacemide showed a weak anticonvulsant activity. Milacemide was then structurally modified to give rise to safinamide, which in turn produced robust anticonvulsant activity. The underlying mechanism behind this action of safinamide is attributed to the inhibition of voltage gated calcium and sodium channels. Moreover, owing to the importance of ion channels in maintaining neuronal circuitry and neurotransmitter release, numerous studies explored the potential of safinamide in neurological diseases including PD, stroke, multiple sclerosis and neuromuscular disorders such as Duchenne muscular dystrophy and non-dystrophic myotonias. Nevertheless, evidence from multiple preclinical studies suggested a potent, selective and reversible inhibitory activity of safinamide against monoamine oxidase (MAO)-B enzyme which is responsible for degrading dopamine, a neurotransmitter primarily implicated in the pathophysiology of PD. Therefore, clinical studies were conducted to assess safety and efficacy of safinamide in PD. Indeed, results from various Phase 3 clinical trials suggested strong evidence of safinamide as an add-on therapy in controlling the exacerbation of PD. This review presents a thorough developmental history of safinamide in PD and provides comprehensive insight into plausible mechanisms via which safinamide can be explored in other neurological and muscular diseases.

Placebo in epilepsy

Placebos impact epilepsy in a number of ways. Through randomized clinical trials, explicit clinical use, and also through implicit clinical use, placebos play a role in epilepsy. This chapter will discuss the reasons placebo is used, the determinants of placebo response in epilepsy, observations about placebo specific to epilepsy, and ways in which clinical trial design is impacted by placebo.

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.

Natural variability in seizure frequency: Implications for trials and placebo

BACKGROUND

Changes in patient-reported seizure frequencies are the gold standard used to test efficacy of new treatments in randomized controlled trials (RCTs). Recent analyses of patient seizure diary data suggest that the placebo response may be attributable to natural fluctuations in seizure frequency, though the evidence is incomplete. Here we develop a data-driven statistical model and assess the impact of the model on interpretation of placebo response.

METHODS

A synthetic seizure diary generator matching statistical properties seen across multiple epilepsy diary datasets was constructed. The model was used to simulate the placebo arm of 5000 RCTs. A meta-analysis of 23 historical RCTs was compared to the simulations.

RESULTS

The placebo 50 %-responder rate (RR50) was 27.3 ± 3.6 % (simulated) and 21.1 ± 10.0 % (historical). The placebo median percent change (MPC) was 22.0 ± 6.0 % (simulated) and 16.7 ± 10.3 % (historical).

CONCLUSIONS

A statistical model of daily seizure count generation which incorporates quantities related to the natural fluctuations of seizure count data produces a placebo response comparable to those seen in historical RCTs. This model may be useful in better understanding the seizure count fluctuations seen in patients in other clinical settings.

Are Patients With Schizophrenia Spectrum Disorders More Prone to Manifest Nocebo-Like-Effects? A Meta-Analysis of Adverse Events in Placebo Groups of Double-Blind Antipsychotic Trials

Background: Antipsychotic clinical trials use to present adverse events (AEs) for the drug under evaluation to treat schizophrenia. Interestingly, patients who receive the placebo during antipsychotic trials often report several AEs, but little is known about the essence of these negative effects in patients with schizophrenia spectrum disorders (SCD). In the present meta-analysis, we evaluated the relationship between the level of psychiatric symptomatology expressed as Positive and Negative Syndrome Scale (PANSS) scores and the rates of AEs reported in the placebo arms of double-blind clinical trials, for commonly prescribed atypical antipsychotic medications.

Methods: We selected 58 clinical trials describing AEs in SCD placebo groups, which compared atypical antipsychotic medications with placebo. A total of 6,301 placebo-treated patients were considered. AE profiles of the class were clusterized using MedDRA classification and analysed using a meta-regression approach.

Results: In the placebo arms the proportions of patients with any AE was 66.3% (95% CI: 62.7–69.8%). The proportion of withdrawal of patients treated with placebo because of AEs was 7.2% (95% CI: 5.9–8.4%). Interestingly, the AEs in the placebo arms corresponded to those of the antipsychotic-atypical-medication-class against which the placebo was compared. Namely, using meta-regression analysis we found an association between the level of psychiatric symptomatology measured with PANSS scores and higher AEs reported as nervous system (p = 0.020) and gastrintestinal disorders (p = 0.004). Moreover, the level of a higher psychiatric symptomatology expressed with PANSS scores was also related with higher AEs associated with psychiatric symptoms (p = 0.017).

Conclusion: These findings emphasise that the AEs in placebo arms of clinical trials of antipsychotic medications were substantial. Importantly, a higher level of psychiatric symptomatology makes SCD patients more prone to express AEs, thus contributing to possible drop-outs and to a lower adherence to treatments. These results are consistent with the expectation theory of placebo and nocebo effects.

Tolerability of new antiepileptic drugs: a network meta-analysis

OBJECTIVE

The objective of this study was to perform a comparative assessment of tolerability of all licensed new antiepileptic drugs (AEDs) through a network meta-analysis (NMA) including all placebo-controlled double-blind clinical trials (RCTs) in all conditions in which these drugs have been tested.

METHODS

NMA with a frequentist approach was used to compare proportions of patients withdrawing because of adverse events (AEs). Analyses were conducted for all therapeutic doses pooled and specifically for high therapeutic doses. Patients treated with non-therapeutic doses of each drug were excluded.

RESULTS

A total of 195 RCTs were included in the current analysis, comprising a total of 28,013 patients treated with AEDs and 17,908 patients treated with placebo. RCTs included in the analysis were 8 for brivaracetam; 5 for eslicarbazepine; 22 for gabapentin; 7 for lacosamide; 14 for levetiracetam; 14 for lamotrigine; 6 for oxcarbazepine; 9 for perampanel; 50 for pregabalin; 5 for tiagabine; 36 for topiramate; 7 for zonisamide; 4 for gabapentin-extended formulation (ER); 2 each for levetiracetam-ER, lamotrigine-ER, and topiramate-ER; and 1 each for oxcarbazepine-ER and pregabalin-ER. Brivaracetam, gabapentin, gabapentin-ER, and levetiracetam had a significantly lower withdrawal rate compared to several other AEDs, while eslicarbazepine, lacosamide, oxcarbazepine, and topiramate had a higher withdrawal rate. Perampanel, lamotrigine, pregabalin, tiagabine, and zonisamide showed an intermediate pattern of tolerability. Additional analysis has been conducted through selection of highly recommended doses for each drug. This analysis has roughly confirmed results of head to head comparisons of the all-dose analysis, with some exceptions. A further analysis has been conducted after exclusion of RCTs in which patients were allocated to the therapeutic dose of the experimental drug without titration, and it failed to show clinically important differences.

SIGNIFICANCE

Relevant differences in short-term tolerability of AEDs have been observed between AEDs. Brivaracetam, gabapentin, and levetiracetam show the best tolerability profile while other AEDs are at higher risk for intolerable adverse effects.

Efficacy and tolerability of brivaracetam compared to lacosamide, eslicarbazepine acetate, and perampanel as adjunctive treatments in uncontrolled focal epilepsy: Results of an indirect comparison meta-analysis of RCTs

BACKGROUND

Brivaracetam (BRV), eslicarbazepine acetate (ESL), lacosamide (LCM), and perampanel (PER) have been recently marketed as adjunctive treatments for focal onset seizures. To date, no randomized controlled trial (RCT) has directly compared BRV with ESL, LCM, or PER.

PURPOSE

To compare BRV with the other add-on AEDs in patients with uncontrolled focal epilepsy, estimating their efficacy and tolerability through an adjusted, common-reference based indirect comparison meta-analysis.

METHODS

We systematically searched RCTs in which add-on treatment with ESL or LCM in patients with focal onset seizures have been compared with placebo. Efficacy and tolerability outcomes were considered. Random-effects Mantel-Haenszel meta-analyses were performed to obtain odds ratios (ORs) for the efficacy of BRV, LCM, ESL, or PER versus placebo. Adjusted indirect comparisons were then made between BRV and the other three AEDs using the obtained results, comparing the minimum and the highest effective recommended daily dose of each drug.

RESULTS

Seventeen RCTs, with a total of 4971 patients were included. After adjusting for dose-effects, indirect comparisons showed no difference between BRV and LCM, ESL, or PER for responder rate and seizure freedom. Lower adverse events were observed with high dose BRV compared to high dose ESL or PER, but no difference was found in withdrawing because of adverse events.

CONCLUSIONS

Indirect comparisons do not demonstrate a significant difference in efficacy between add-on BRV and LCM, ESL, or PER in focal epilepsy, and might suggest a better tolerability of BRV than ESL, and possibly also PER, at the highest effective recommended dose.

The New Antiepileptic Drugs: Their Neuropharmacology and Clinical Indications

The administration of antiepileptic drugs (AEDs) is the first treatment of epilepsy, one of the most common neurological diseases. Therapeutic guidelines include newer AEDs as front-line drugs; monotherapy with new AEDs is delivered in Japan. While about 70% of patients obtain good seizure control by taking one to three AEDs, about 60% experience adverse effects and 33% have to change drugs. Compared to traditional AEDs, the prolonged administration of new AEDs elicits fewer adverse effects and fewer drug interactions and their teratogenicity may be lower. These characteristics increase drug compliance and allow combination therapy for drug-resistant epilepsy, although the antiepileptic effects of the new AEDs are not greater than of traditional AEDs. Comorbidities are not rare in epileptics; many adult patients present with stroke and brain tumors. In stroke patients requiring risk control and in chemotherapy-treated brain tumor patients, their fewer drug interactions render the new AEDs advantageous. Also, new AEDs offer favorable side benefits for concurrent diseases and conditions. Patients with stroke and traumatic brain injury often present with psychiatric/behavioral symptoms and cognitive impairment and some new AEDs alleviate such symptoms. This review presents an outline of the new AEDs used to treat adult patients based on the pharmacological activity of the drugs and discusses possible clinical indications from the perspective of underlying causative diseases and comorbidities.

Generic-to-generic lamotrigine switches in people with epilepsy: the randomised controlled EQUIGEN trial

BACKGROUND

Patients and clinicians share concerns that generic drug substitution might lead to loss of efficacy or emergence of adverse events. In this trial, we assessed US Food and Drug Administration (FDA) bioequivalence standards by studying the effects of switching between two disparate generic immediate-release lamotrigine products in patients with epilepsy.

METHODS

The Equivalence among Generic Antiepileptic Drugs (EQUIGEN) chronic-dose study was a randomised, double-blind, crossover study that enrolled adults (aged ≥18 years) with epilepsy from six epilepsy centres at academic institutions across the USA who were receiving immediate-release lamotrigine dosed at 100 mg, 200 mg, 300 mg, or 400 mg twice daily. Eligible patients were randomly allocated (1:1) to one of two treatment sequences (sequence 1 or sequence 2), comprising four study periods of 14 days each. During each 14-day treatment period, patients received balanced doses of an oral generic lamotrigine product every 12 h (200-800 mg total, identical to lamotrigine dose prior to study enrolment); after each 14-day period, patients were crossed over to receive the other generic product. Computer-based randomisation was done using random permuted blocks of size two or four for each site to prevent sequence predictability. Both patients and study personnel were masked to the generic products selected, their predicted exposure (ie, "high" vs "low"), and their group allocation. The primary outcome of this trial was bioequivalence between the generic products, which was assessed at the end of the study through a comparison of maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC) for each product in the analysis population (all patients who completed all four treatment periods). Bioequivalence was established if the 90% CIs of the ratios of these two parameters for the two products were within equivalence limits (80-125%) in the analysis population. This study is registered with ClinicalTrials.gov\, number NCT01713777.

FINDINGS

Between April 25, 2013, and Aug 12, 2014, 35 eligible patients were enrolled and randomly assigned to treatment sequence 1 (n=15) or treatment sequence 2 (n=20). 33 patients completed all four treatment periods and were included in the primary outcome analysis. The 90% CIs of the ratios of both Cmax and AUC were within equivalence limits (AUC 90% CI 98-103, Cmax 90% CI 99-105), showing that lamotrigine exposures were equivalent between the generic products. No significant changes in seizure frequency or adverse events were recorded. No deaths, study-related serious adverse events, or changes in clinical laboratory values or vital signs occurred during this study.

INTERPRETATION

Disparate generic lamotrigine products in patients with epilepsy showed bioequivalence with no detectable difference in clinical effects, confirming that US Food and Drug Administration bioequivalence standards are appropriate.

FUNDING

American Epilepsy Society, Epilepsy Foundation, and US Food and Drug Administration.

Response to placebo in clinical epilepsy trials--Old ideas and new insights

Randomized placebo-controlled trials are a mainstay of modern clinical epilepsy research; the success or failure of innovative therapies depends on proving superiority to a placebo. Consequently, understanding what drives response to placebo (including the "placebo effect") may facilitate evaluation of new therapies. In this review, part one will explore observations about placebos specific to epilepsy, including the relatively higher placebo response in children, apparent increase in placebo response over the past several decades, geographic variation in placebo effect, relationship to baseline epilepsy characteristics, influence of nocebo on clinical trials, the possible increase in (SUDEP) in placebo arms of trials, and patterns that placebo responses appear to follow in individual patients. Part two will discuss the principal causes of placebo responses, including regression to the mean, anticipation, classical conditioning, the Hawthorne effect, expectations from symbols, and the natural history of disease. Included in part two will be a brief overview of recent advances using simulations from large datasets that have afforded new insights into causes of epilepsy-related placebo responses. In part three, new developments in study design will be explored, including sequential parallel comparison, two-way enriched design, time to pre-randomization, delayed start, and cohort reduction techniques.

Characterization of the adverse events profile of placebo-treated patients in randomized controlled trials on drug-resistant focal epilepsies

In epilepsy trials a substantial proportion of patients receiving placebo has some improvement or experience adverse events (AEs) which match those related to active drug. The characterization of factors influencing these responses is crucial for a better comprehension of study results and to improve design of new trials. Seventy-one placebo-controlled, double-blind trials in drug-resistant focal epilepsies has been selected. The effect of multiple factors on some outcome measures were explored using a meta-regression model. For subjective and objective AEs, risk difference (RD) was calculated and entered in an inverse variance-weighted linear meta-regression model as independent variable to evaluate the relationship with data reported in placebo-treated patients. The number of study arms influence the percentage of patients withdrawing because of AEs and the highest dose of the experimental drug used in each RCT correlates with withdrawal because of AEs and with subjective AEs. Higher titration speed is associated with lower percentages of responders and higher reporting of both objective and subjective AEs. The correlation between proportions of placebo-treated patients with subjective and objective neurological AEs and relative RD, was significant (P = 0.002 r = 0.364 and P < 0.001 r = 0.650, respectively). Efficacy and tolerability outcomes of the placebo groups are intrinsically tied to the trial methodology and to the outcomes observed in patients treated with the active drug. The correlation for objective and subjective AEs between RD and the placebo-treated patients suggest that investigators are influenced by factors which operate within each specific trial.