Controlled clinical trials
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Control Clin Trials · Dec 1997
Comparative StudyCumulating evidence from randomized trials: utilizing sequential monitoring boundaries for cumulative meta-analysis.
We propose the adaptation of classical monitoring boundaries for use in cumulative meta-analysis as guidelines for deciding when accumulating evidence is statistically significant and medically convincing. The interpretation of information from a randomized controlled trial is compared with that from a meta-analysis. The concept of optimal information size for a meta-analysis is developed and used to adapt monitoring boundaries to cumulative meta-analysis.
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Control Clin Trials · Dec 1997
Review Comparative StudyMeta-analysis of randomized trials: looking back and looking ahead.
Meta-analyses as currently practiced are usually retrospective. They can be made more rigorous by developing a protocol that incorporates prospectively the elements that are usually necessary in a well-designed trial. ⋯ Once the large trials have been completed, they could be brought together within the framework of a meta-analysis to estimate the overall treatment effect with greater confidence and to explore the effects in various subgroups. This article explores the value and limitations of meta-analyses and suggests ways of improving their conduct and interpretation.
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Control Clin Trials · Oct 1997
Meta AnalysisThe relationship between study design, results, and reporting of randomized clinical trials of HIV infection.
We examined whether the study design of randomized clinical trials for medications against human immunodeficiency virus (HIV) may affect the results and whether the outcomes of these trials affect reporting and publication. We used a database of 71 published randomized HIV-related drug efficacy trials and considered the following study design factors: endpoint definition and method of analysis, masked design, sample size, and duration of follow-up. Large variation was noted in the methods of analysis for surrogate endpoints. ⋯ We identified several examples of trials with "negative" results that have remained unpublished for a long time. In conclusion, study design factors may have an impact on the magnitude and significance of the treatment effect in HIV-related trials. Bias in reporting can further affect the information that these studies provide.
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Control Clin Trials · Aug 1997
Recruitment for controlled clinical trials: literature summary and annotated bibliography.
This article is a literature summary and annotated bibliography of research on recruitment for controlled clinical trials published through 1995. It extends and revises a similar review published in this journal a decade ago. The current commentary focuses on intervening developments in recruitment, including diverse populations, HIV trials, primary prevention trials, recruitment strategies, overall planning and management, patient and physician attitudes, adherence, generalizability, and cost. ⋯ With increasingly limited funding to conduct clinical trials, efforts to quantify and reduce recruitment costs are being made. While over 4000 titles were identified, primarily by MEDLINE literature search, the articles summarized emphasize data-supported and -confirmed conclusions, and broad coverage of disease areas. We annotate here 91 outstanding articles useful for formulation of overall recruitment approaches in clinical trials.
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Control Clin Trials · Feb 1997
Randomized Controlled Trial Clinical TrialOutcome assessment for clinical trials: how many adjudicators do we need? Canadian Lung Oncology Group.
Considerable effort is often expended to adjudicate outcomes in clinical trials, but little has been written on the administration of the adjudication process and its possible impact on study results. As a case study, we describe the function and performance of an adjudication committee in a large randomized trial of two diagnostic approaches to potentially operable lung cancer. Up to five independent adjudicators independently determined two primary outcomes: tumor status at death or at final follow-up and the cause of death. ⋯ This level of effort could be substantially reduced by using fewer adjudicators with little impact on the results. Thus, we suggest that when high observer agreement is demonstrated or anticipated, adjudication committees should consist of no more than three members. Further work is needed to evaluate if smaller committees are adequate to detect small but important treatment effects or if they compromise validity when the level of adjudicator agreement is lower.