Better to be in The Placebo Arm for Trials of Neurological Therapies?

A Call to Revise the Declaration of Helsinki's Placebo Guidelines

Since its introduction in 1964, the World Medical Association's Declaration of Helsinki-Ethical Principles for Medical Research Involving Human Subjects has enshrined the importance of safeguarding the well-being of human subjects in clinical research. The Declaration has undergone seven revisions, often in response to requests for clarification. I want to argue that the Declaration is in need of another revision in light of recent discoveries in placebo research.

Ethical and epistemic issues in the design and conduct of pragmatic stepped-wedge cluster randomized clinical trials

Stepped-wedge cluster randomized trial (SW-CRT) designs are increasingly employed in pragmatic research; they differ from traditional parallel cluster randomized trials in which an intervention is delivered to a subset of clusters, but not to all. In a SW-CRT, all clusters receive the intervention under investigation by the end of the study. This approach is thought to avoid ethical concerns about the denial of a desired intervention to participants in control groups. Such concerns have been cited in the literature as a primary motivation for choosing SW-CRT design, however SW-CRTs raise additional ethical concerns related to the delayed implementation of an intervention and consent. Yet, PCT investigators may choose SW-CRT designs simply because they are concerned that other study designs are infeasible. In this paper, we examine justifications for the use of SW-CRT study design, over other designs, by drawing on the experience of the National Institutes of Health's Health Care Systems Research Collaboratory (NIH Collaboratory) with five pragmatic SW-CRTs. We found that decisions to use SW-CRT design were justified by practical and epistemic reasons rather than ethical ones. These include concerns about feasibility, the heterogeneity of cluster characteristics, and the desire for simultaneous clinical evaluation and implementation. In this paper we compare the potential benefits of SW-CRTs against the ethical and epistemic challenges brought forth by the design and suggest that the choice of SW-CRT design must balance epistemic, feasibility and ethical justifications. Moreover, given their complexity, such studies need rigorous and informed ethical oversight.

Design of placebo-controlled randomized trials of anticancer agents: Ethical considerations based on a review of published trials

BACKGROUND

Limited information exists about the design of placebo-controlled cancer trials. Through a systematic review of trials published in 2013, we describe placebo use in randomized trials testing anticancer agents and analyze strategies that increase exposure to the experimental regimen.

METHODS

Trials were classified as add-on (placebo in combination with standard treatment) or placebo-only. Strategies to allow more than half of the participants to receive the experimental regimen were reviewed. The risk-benefit ratio of receiving the experimental agent was considered favorable if the difference in primary outcome was significant (p ≤ 0.05), neutral if there was no significant difference in the primary outcome and the experimental agent did not add substantial toxicity, and unfavorable otherwise.

RESULTS

Eighty trials were included (32,694 participants). Most trials were add-on (69%). The risk-benefit outcome was favorable, neutral, and unfavorable to the experimental agent in 52%, 32%, and 16% of placebo-only trials and 25%, 53%, and 22%, respectively, of add-on trials. Four strategies increased exposure to the experimental regimen: one-way crossover (23%), uneven randomization (21%), three-arms (13%), and randomized discontinuation design (4%); these strategies were used more often in placebo-only trials.

CONCLUSION

A minority of participants received placebo alone and strategies to increase experimental exposure were used commonly. Fewer than half of the studies had favorable outcomes, thus defending the use of placebo controls, when there is no established treatment. Strategies that increase patient exposure to experimental agents rather than placebo may expose them to non-beneficial, sometimes toxic, experimental agents.

Neurodegenerative Implications of Neuronal Cytoplasmic Protein Dysfunction in Response to Environmental Contaminants

Neurodegenerative diseases account for a significant portion of public health concerns particularly in the aging population. The dysfunction of interfilament proteins has been identified as a key event in the initiation of neurodegeneration and subsequent progression to neurodegenerative diseases. In addition, several studies have found associations between the dysfunction of interfilament proteins and exposure to environmental contaminants. Therefore, in this review, the role of interfilament proteins in neuronal cells, their connection to neurotoxicity from environmental contaminants, and finally the resulting neurodegeneration are discussed.

Risks and benefits of unapproved disease-modifying treatments for neurodegenerative disease

OBJECTIVE

To determine whether patients randomized to unapproved, disease-modifying interventions in neurodegenerative disease trials have better outcomes than patients randomized to placebo by performing a systematic review and meta-analysis of risk and benefit experienced by patients in randomized placebo-controlled trials testing investigational treatments for Alzheimer disease, Parkinson disease, Huntington disease, or amyotrophic lateral sclerosis (ALS).

METHODS

We searched MEDLINE, Embase, and ClinicalTrials.gov for results of randomized trials testing non-Food and Drug Administration-approved, putatively disease-modifying interventions from January 2005 to May 2018. Trial characteristics were double-extracted. Coprimary endpoints were the treatment advantage over placebo on efficacy (standardized mean difference in outcomes) and safety (risk ratios of serious adverse events and withdrawals due to adverse events), calculated with random effects meta-analyses. The study was registered on PROSPERO (CRD42018103798).

RESULTS

We included 113 trials (n = 39,875 patients). There was no significant efficacy advantage associated with assignment to putatively disease-modifying interventions compared to placebo for Alzheimer disease (standardized mean difference [SMD] -0.03, 95% confidence interval [CI] -0.07 to 0.01), Parkinson disease (SMD -0.09, 95% CI -0.32 to 0.15), ALS (SMD 0.02, 95% CI -0.25 to 0.30), or Huntington disease (0.02, 95% CI -0.27 to 0.31). Patients with Alzheimer disease assigned to active treatment were at higher risk of experiencing serious adverse events (risk ratio [RR] 1.15, 95% CI 1.04-1.27) and withdrawals due to adverse events (RR 1.44, 95% CI 1.21-1.70).

CONCLUSIONS

Assignment to active treatment was not beneficial for any of the indications examined and may have been slightly disadvantageous for patients with Alzheimer disease. Our findings suggest that patients with neurodegenerative diseases are not, on the whole, harmed by assignment to placebo when participating in trials.