Controlled clinical trials
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Control Clin Trials · Sep 1986
Randomized Controlled Trial Clinical TrialQuality control of screening procedures in the Multiple Risk Factor Intervention Trial.
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When designing a clinical trial to show whether a new or experimental therapy is as effective as a standard therapy (but not necessarily more effective), the usual null hypothesis of equality is inappropriate and leads to logical difficulties. Since therapies cannot be shown to be literally equivalent, the appropriate null hypothesis is that the standard therapy is more effective than the experimental therapy by at least some specified amount. ⋯ The required sample size may be larger for either null hypothesis formulation than for the other, depending on the specific assumptions made. Reporting results in terms of confidence intervals is especially useful for this type of trial.
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Control Clin Trials · Jun 1981
Introduction to sample size determination and power analysis for clinical trials.
The importance of sample size evaluation in clinical trials is reviewed and a general method is presented from which specific equations are derived for sample size determination or the analysis of power for a wide variety os statistical procedures. The method is discussed and illustrated in relation to the t test, tests for proportions, tests of survival time, and tests for correlations as they commonly occur in clinical trials. Most of the specific equations reduce to a simple general form for which tables are presented.
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The author begins by considering what kinds of questions should be used to establish informed consent, and particularly seeks to establish criteria for a valid consent; both for the person who asks the patient for consent, and for the person who judges the consent as a valid one. Then some variables--duration, severity and kind of illness, and type of personality--are considered that may influence consent. With regard to the discrepancy between the law and reality, it is proposed not to interpret the requirements of the law in a sense of all-or-none but as a demand that must be adapted adequately in content and in time to the individual patient and that they should be embedded in the therapeutic process that is an expression of the so-called "therapeutic privilege." Finally, it is asked, what are the consequences of information and consent on the results of therapy as well as of research? The necessity of empirically based research to answer these unsolved questions is emphasized.