Controlled clinical trials
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Control Clin Trials · Jun 2003
Randomized Controlled Trial Clinical TrialPerceptions of equipoise are crucial to trial participation: a qualitative study of men in the ProtecT study.
Recruitment to trials is known to be difficult. Previous research suggests that a crucial factor may be participants' difficulty with the concept of randomization. This study explored patients' perceptions of randomization and reasons for consent or refusal to participate in the ProtecT study (a randomized trial of surgery, radiotherapy, and monitoring for localized prostate cancer). ⋯ Belief in clinical equipoise was key to participants' consent to randomization. Ensuring patients understand and accept equipoise may thus increase their readiness to consent to participate in trials. A priority for future research is to focus on the provision and presentation of suitable and effective trial information, concentrating in particular on the neglected concept of clinical equipoise.
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Control Clin Trials · Apr 2003
Randomized Controlled Trial Clinical TrialElicitation of prior distributions for a phase III randomized controlled trial of adjuvant therapy with surgery for hepatocellular carcinoma.
A randomized, controlled clinical trial of radioactive iodine tagged with lipiodol in patients with resected hepatocellular carcinoma was criticized for its early stopping and resulting small sample size. To clarify its results, a new, larger multicenter trial was therefore proposed. ⋯ They can also be used in Bayesian analyses, both at the interim stage(s) as well as at the end of the trial. We illustrate these analyses, assuming that the data resulting from the new trial was the same as that obtained in the earlier trial when it was stopped.
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Control Clin Trials · Apr 2003
Comparative Study Clinical Trial Controlled Clinical TrialPatient compliance with paper and electronic diaries.
Paper diaries are commonly used in health care and clinical research to assess patient experiences. There is concern that patients do not comply with diary protocols, possibly invalidating the benefit of diary data. Compliance with paper diaries was examined with a paper diary and with an electronic diary that incorporated compliance-enhancing features. ⋯ For the electronic diary, the actual compliance rate was 94%. In summary, participants with chronic pain enrolled in a study for research were not compliant with paper diaries but were compliant with an electronic diary with enhanced compliance features. The findings call into question the use of paper diaries and suggest that electronic diaries with compliance-enhancing features are a more effective way of collecting diary information.
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Control Clin Trials · Apr 2003
Design and analysis of clinical trials with a bivariate failure time endpoint, with application to AIDS Clinical Trials Group Study A5142.
This paper investigates the use of a bivariate endpoint in clinical trials of antiretroviral drugs to treat infection with the HIV. While they provide the most reliable information about treatment effects, clinical events such AIDS or death are relatively rare among newly treated patients with HIV infection. As a result, surrogate endpoints, such as time to virological failure and time to regimen termination, are generally used in place of clinical endpoints in studies that enroll patients without previous treatment experience. ⋯ In this paper, we consider the bivariate endpoint of time to virological failure and time to regimen termination. Analysis of a bivariate endpoint requires appropriate statistical methods that maintain the experimentwise type I error rate when making simultaneous inference with respect to each endpoint. This article outlines such methods and compares their small sample properties using the simulation study that was executed for the purpose of designing a current AIDS clinical trial.
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Control Clin Trials · Apr 2003
Stratified experiments reexamined with emphasis on multicenter trials.
In many stratified experiments the researcher fixes the total sample size but either cannot or does not exert control over the sample size per stratum. A classic example is a randomized, two-treatment, multicenter clinical trial-the total sample sizes per treatment group are fixed by design but the sample sizes per center are allowed to vary. ⋯ We propose an alternative method of analysis that explicitly accounts for the randomness of the stratum sizes and illustrate its validity using simulations. A reanalysis of published data from a 29-center clinical trial serves to reinforce the key points.