Early stopping rules--clinical perspectives and ethical considerations

Putting participants and study partners FIRST when clinical trials end early

Between 2018 and 2019, multiple clinical trials ended earlier than planned, resulting in calls to improve communication with and support for participants and their study partners ("dyads"). The multidisciplinary Participant Follow-Up Improvement in Research Studies and Trials (Participant FIRST) Work Group met throughout 2021. Its goals were to identify best practices for communicating with and supporting dyads affected by early trial stoppage. The Participant FIRST Work Group identified 17 key recommendations spanning the pre-trial, mid-trial, and post-trial periods. These focus on prospectively allocating sufficient resources for orderly closeout; developing dyad-centered communication plans; helping dyads build and maintain support networks; and, if a trial stops, informing dyads rapidly. Participants and study partners invest time, effort, and hope in their research participation. The research community should take intentional steps toward better communicating with and supporting participants when clinical trials end early. The Participant FIRST recommendations are a practical guide for embarking on that journey.

Systematic qualitative review of the literature on data monitoring committees for randomized controlled trials

Aims To systematically review the published literature on data monitoring committees (DMCs) for randomized controlled trials (RCT) and summarize information and opinions on best practice. This was part of the DAMOCLES project. Methods A systematic and comprehensive search of five online bibliographic databases was performed, identifying 4007 potentially relevant articles. These were assessed in two stages by the authors. The 84 most relevant articles were agreed and were supplemented with extracts from 16 books: ultimately, 100 sources were reviewed. A series of 23 questions plus subquestions were developed to structure the data extraction and interpretation process.

Results Much has been written about DMCs but by a rather small community of authors. The papers included some results of surveys, but were mainly opinion pieces based on the authors' beliefs, practices and experiences. There is a lack of empirical evidence for many aspects of DMCs. There was a great range of detail in the literature relating to the prespecified questions. It was generally agreed that interim monitoring of accumulating data was necessary in some form for most trials. Questions such as membership of the DMC featured widely in the literature with opinions and practice ranging from 3–20 members, of whom between none and all should be independent. There was a consensus that formal statistical methods should be used as tools to guide decision making rather than as hard rules. Conversely, topics such as the training and experience required for DMC membership were discussed in very few papers.

Conclusions There is a consensus in the published literature in a number of areas, although there are many different models for structure and functions of a DMC. While uncertainty remains about some issues, it is strongly recommended that an explicit set of guidelines (Charter) is prepared for each DMC prior to the start of the trial specifying clearly how it will operate.

Study protocol for a randomized, double-blind, placebo-controlled trial of a single preoperative steroid dose to prevent nausea and vomiting after thyroidectomy: the tPONV study

BACKGROUND

Postoperative nausea and vomiting after general anesthesia is not only an unpleasant problem affecting 20-30% of surgical patients but may also lead to severe postoperative complications. There is a particularly high incidence of postoperative nausea and vomiting following thyroidectomy. Dexamethasone has been described as highly effective against chemotherapy-induced nausea and vomiting and has been proposed as a first-line method of postoperative nausea and vomiting prophylaxis. Despite this possible beneficial effect, the prophylactic administration of dexamethasone before surgery to prevent or ameliorate postoperative nausea and vomiting has not been established. A bilateral superficial cervical plexus block during thyroid surgery under general anesthesia significantly reduces pain. Of even greater clinical importance, this block prevents the need for postoperative opioids. Therefore, patients undergoing thyroidectomy and a bilateral superficial cervical plexus block are an ideal group to investigate the efficacy of dexamethasone for postoperative nausea and vomiting. These patients have a high incidence of postoperative nausea and vomiting and do not require opioids. They have no abdominal surgery, which can cause nausea and vomiting via a paralytic ileus. Combined with the highly standardized anesthesia protocol in use at our institution, this setting allows all known biases to be controlled.

METHODS/DESIGN

We will perform a parallel two-arm, randomized (1:1), double-blind, placebo-controlled, single-center trial. Adults (≥18 years) scheduled for primary partial or total thyroidectomy because of a benign disease will be eligible for inclusion. The participants will be randomized to receive a single, intravenous preoperative dose of either 8 mg of dexamethasone in 2 ml saline (treatment group) or saline alone (placebo group). All the patients will receive a bilateral superficial cervical plexus block and standardized anesthesia. The primary outcome will be the incidence of postoperative nausea and vomiting. A total of 152 patients will be recruited, providing 80% power to detect a 50% reduction in the incidence of postoperative nausea and vomiting. Any patients who require opioid treatment will be excluded from the per-protocol analysis.

DISCUSSION

In the present protocol, we reduced bias to the greatest extent possible. Thus, we expect to definitively clarify the efficacy of dexamethasone for postoperative nausea and vomiting prophylaxis.

TRIAL REGISTRATION

http://www.clinicaltrials.gov: NCT01189292.

Continuous safety monitoring for randomized controlled clinical trials with blinded treatment information. Part 1: Ethical considerations

The protection of patient safety is the principal responsibility of clinical trial investigators, and must be assured even if that were to prevent successful completion of a trial. Yet, the decision to prematurely stop a blinded, randomized controlled clinical trial can be extremely complicated, involving a tangle of ethical, statistical, and practical issues. Questions are quickly answered when conclusive evidence of harm has been established for trial participants, or when the potential for harm exceeds an acceptable limit of comfort for an oversight body. Less readily addressed are those situations in which early alarms warn of possible harm, but the data are too preliminary or incomplete to reach a satisfactory decision as to whether or not to stop the study. Early study termination without sufficient evidence disallows the study question from being answered and may allow an inferior treatment to remain in use, or prevent a superior one from being discovered. Even without early stopping, as a study proceeds, worrisome trends may lead to overzealous (or overly cautious) looks at study data which could jeopardize the integrity of the findings. Trial investigators and safety monitoring groups, aided by objective statistical rules and thoughtful deliberations, share responsibility for patient welfare. Statistical guidelines must not frustrate ethical concerns, but, rather, should be designed to promote the highest ethical and scientific outcomes possible, safeguarding both trial participants and the public - the ultimate beneficiaries of clinical trials.

Clinical Trial Design Issues in the Era of Targeted Therapies

Although our lack of effective therapies mandates the development of new, molecularly targeted therapies, a number of issues in the design of clinical trials and their end points remain to be considered.

Framework for bioethical assessment of an article on therapy

OBJECT

Frameworks for scientific assessment of articles on therapy published in the medical literature have become available and will likely enhance the quality of medical research that is published in peer-reviewed journals. Comprehensive frameworks do not exist for the assessment of bioethical issues pertaining to research on human volunteers.

METHODS

The authors have developed a framework consisting of ethical dimensions or questions that they suggest should be applied to assess the bioethical integrity of articles on therapy. Thirteen questions were developed and discussed in the context of current bioethical principles, and examples were applied where possible.

CONCLUSIONS

The simple framework the authors have developed offers a method to assess key bioethical issues surrounding an article on therapy and probably defines the minimum standard to which such articles should be held. Many ethical questions cannot yet be answered based on available information or bioethical theories. The authors are not suggesting that their framework is comprehensive; refinements and individualization of it to fit specific studies are probably required by each clinician-researcher who designs a therapy trial and reports its results.

Assessment and monitoring in clinical trials when survival curves have distinct shapes: a Bayesian approach with Weibull modelling

The comparison of Weibull distributions with unequal shape parameters, in the case of right censored survival data obtained from independent samples, is considered within the framework of Bayesian statistical methodology. The procedures are illustrated with the example of a mortality study where a new treatment is compared to a placebo. The posterior distributions about relevant parameters, which may provide support for a conclusion of clinical superiority of the treatment, and the predictive distributions, which may guide decision about early stopping at an interim analysis, are considered for a class of appropriate priors.

A Bayesian approach to Weibull survival models--application to a cancer clinical trial

In this paper we outline a class of fully parametric proportional hazards models, in which the baseline hazard is assumed to be a power transform of the time scale, corresponding to assuming that survival times follow a Weibull distribution. Such a class of models allows for the possibility of time varying hazard rates, but assumes a constant hazard ratio. We outline how Bayesian inference proceeds for such a class of models using asymptotic approximations which require only the ability to maximize the joint log posterior density. We apply these models to a clinical trial to assess the efficacy of neutron therapy compared to conventional treatment for patients with tumours of the pelvic region. In this trial there was prior information about the log hazard ratio both in terms of elicited clinical beliefs and the results of previous studies. Finally, we consider a number of extensions to this class of models, in particular the use of alternative baseline functions, and the extension to multi-state data.

Simple Bayesian analysis in clinical trials: a tutorial

In this tutorial paper we give a simple Bayesian analysis of data that arise in clinical trials. We consider the case when there are two treatment groups and the response in each group can be assumed to be binomially distributed. We also assume that prior beliefs about the rate parameter in each group can be adequately expressed by a Beta distribution. Using such a model approximate posterior inferences can then be made about the odds ratio between the two groups. We illustrate this methodology by analyzing a randomized trial to assess the benefits of treating patients with carcinoma of the pelvic region (rectum, bladder, colon, cervix) using high-energy fast neutrons as opposed to conventional megavoltage x-rays (photons). In this trial there was prior information about the relative efficacy of neutron therapy based on the beliefs of 10 clinicians. Some of the deficiencies of this simple approach are high-lighted and other approaches to analysis indicated. The paper facilitates practical consideration of a Bayesian approach without the complexities that a fuller analysis necessitates.