Monitoring clinical trials. Dissemination of decisions on interim analyses needs wider debate.
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UNLABELLED: The development of science allows us to take up new investigative challenges. Interpretations of results can be difficult if there is no adequate and complete information about investigative methods applied, course of trial and statistical analyses. The CONSORT group proposed a standardized diagram facilitating an accurate presentation of the randomised trial. The EDEN study is an example of the application of this method, where the studied groups, number of participants, and all procedures can be presented. It is helpful to prepare reports and find necessary data. The first part of the diagram describes the course of recruitment, the second part presents data necessary to estimate the course of the study and data about numbers of patients in each timepoint whilst the third part shows the assessment of caregivers. CONCLUSIONS: The analysis of the course and correctness of the study is legible if the flow diagram is used. It is useful to find the necessary data for statistical analyses at every stage of study. Permanent control of the study allow to avoid bias upsetting the course of the study and influencing its quality. It introduces comprehensible and straight forward presentation of the results.
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Institution/investigator-initiated clinical trials in Canada require adherence to similar regulations and processes required of large pharmaceutical manufacturers. This may require an investigator to file a Clinical Trial Application. This article outlines the responsibilities and actions that are required prior to, during, and after the conduct of an institution/investigator initiated trial.
UNLABELLED: The scientific burden of proof for new therapies and technologies in obstetrics and gynecology has risen steadily over the past 15 to 20 years, and the randomized clinical trial has become integral to this higher standard. Data monitoring and safety committees are now critical components of clinical trials, yet their history, rationale, methods of operation, and overall role have not been well-characterized in the obstetrics and gynecology literature. In this review, an overview of the important and evolving role of data monitoring and safety committees is provided. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians. LEARNING OBJECTIVES: After completion of this article, the reader will be able to describe what a data monitoring and safety committee is, plan who should comprise the DMSC, and outline the functions of a DMSC.
For safety and ethical reasons, a data monitoring committee of a clinical trial may wish to assess the futility of continuing a trial if the currently available data at an interim look show no beneficial effect due to treatment, especially when accompanied by mounting evidence of treatment emergent adverse effects. Stochastic curtailing whereby conditional power is evaluated given currently observed data is one way of evaluating futility. In clinical trials that look at "time-to-event" as the primary outcome, difference between treatment groups with respect to the primary outcome is commonly evaluated using the log-rank test. Although the unconditional power function for the log-rank test has been described previously, its conditional power has not been widely investigated. We describe a method for evaluating conditional power when the log-rank test is used to assess the difference between the survival distributions of two treatment groups with respect to some failure-time outcome. The method is useful under a wide range of assumptions regarding the underlying survival distribution, patient entry distribution, losses to follow-up, and (if applicable) noncompliance, drop-ins, lag in treatment effect, and stratification. This level of applicability is attained by generalizing a flexible Markov chain approach to unconditional power computation, described previously, to compute conditional power.
Data monitoring committees for randomized clinical trials must frequently decide what action, if any, is required for trials whose accrual has been slower than expected, or whose event rates have been less than expected. We discuss in this article some of the practical issues concerning modifying or closing such trials, including what data and analyses could be helpful to the data monitoring committee in their deliberations.
PURPOSE: To compare the selective matrix metalloproteinase inhibitor BAY 12-9566 with the nucleoside analog gemcitabine in the treatment of advanced pancreatic cancer. METHODS: Patients with advanced pancreatic adenocarcinoma who had not previously received chemotherapy were randomly assigned to receive BAY 12-9566 800 mg orally bid continuously or gemcitabine 1,000 mg/m2 administered intravenously on days 1, 8, 15, 22, 29, 36, and 43 for the first 8 weeks, and then days 1, 8, and 15 of each subsequent 28-day cycle. The primary end point was overall survival; secondary end points were progression-free survival, tumor response, quality of life, and clinical benefit. The planned sample size of the study was 350 patients. Two formal interim analyses were planned. RESULTS: The study was closed to accrual after the second interim analysis on the basis of the recommendation of the National Cancer Institute of Canada Clinical Trials Group Data Safety Monitoring Committee. There were 277 patients enrolled onto the study, 138 in the BAY 12-9566 arm and 139 in the gemcitabine arm. The rates of serious toxicity were low in both arms. The median survival for the BAY 12-9566 arm and the gemcitabine arm was 3.74 months and 6.59 months, respectively (P <.001; stratified log-rank test). The median progression-free survival for the BAY 12-9566 and gemcitabine arms was 1.68 and 3.5 months, respectively (P <.001). Quality-of-life analysis also favored gemcitabine. CONCLUSION: Gemcitabine is significantly superior to BAY 12-9566 in advanced pancreatic cancer.
This paper illustrates aspects of data monitoring of clinical trials in the pharmaceutical industry. Formal interim analyses are performed at least in part to address the question of whether the trial should proceed or whether there should be an early termination of the trial. For formal interim analyses, frequently independent data and safety monitoring committees are utilized for monitoring clinical trials, and adjustments to nominal significance levels for test statistics are required. Various statistical methods developed during the last fifteen years are utilized. Administrative interim analyses are those analyses that are performed without any intention to stop the trial as a consequence of those analyses. For administrative interim analyses, adjustments to significance levels may not be required, but results must still be carefully interpreted. Regardless of the interim analyses performed, it is critical that the plans for interim analyses be identified in the study protocol, and the dissemination of interim results be carefully restricted. The following clinical trials sponsored by Merck Sharp and Dohme Research Laboratories (MSDRL) will illustrate these points: CONSENSUS; CONSENSUS II; 4S; Haemophilus influenza type b efficacy trial; famotidine in upper gastrointestinal haemorrhage, and a phase II analgesic study. It is anticipated that data monitoring and interim analysis activities will increase for future clinical trials due to the availability of appropriate statistical methods and improved data management systems.
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In many clinical trials, data are monitored periodically by an external data monitoring committee (DMC). Usually the frequency of these interim 'looks' at the data is prespecified. However, the progress of a clinical trial is unpredictable; often the schedule of looks must be modified. The Lan-DeMets procedure provides a spending function approach which does not require prespecification of the frequency or timing of interim looks. The procedure was developed based on the principle of a continuous Brownian motion process. In this paper we employ more elementary concepts to describe a procedure which is based upon the continuous monitoring of emerging data. The approach is flexible in that it applies to both continuous data monitoring and occasional interim monitoring. Examples are given from real clinical trials.
This paper reports the results of a survey of data monitoring practices of the 12 clinical co-operative groups in cancer sponsored by the National Cancer Institute in the United States. Most of these co-operative groups conduct a large number of active clinical trials in a wide variety of cancers. The number of active phase III trials in 1991 was 244 with nearly 24,000 patients entered on these trials. The survey instrument used in this paper was modified from one originally developed by Geller and Stylianou, supplemented by questions on the responsibilities of data monitoring committees based on Hawkins. Topics covered included general policies and procedures on the monitoring of clinical trials in these groups as well as specific questions on the responsibilities and operational procedures of formal data monitoring committees. Although formal statistical stopping rules are almost always employed in cancer trials in these co-operative groups, use of a formal data monitoring committee is a relatively new, but increasing practice. For a variety of economic and practical reasons, the members of data monitoring committees for cancer trials are rarely independent of the study participants.