assign2_key - Assignment#2 Clinical Trials(100 points Due...

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Assignment #2 Clinical Trials (100 points) Due February 22, 2011 1. (5) Give an example of a randomized clinical trial for which blinding of the treatments would not be possible and indicate why blinding is not possible. Answer: A trial of surgery versus not surgery, e.g. coronary bypass surgery versus optimal medical management. Another example would be a trial of a novel behavioral intervention program aimed at smoking cessation versus usual care. In both cases it is obvious to the study participants and investigators which group they are in. 2. (25) A trial of two drugs, pyrimethamine and clindamycin, for the prevention of toxoplasmic encephalitis (TE) is planned. Clindamycin and pyrimethamine could not be made to look alike, but placebo could be prepared to match each drug. Thus, the investigators proposed a partially blinded placebo- controlled study in which one-half of the patients were to be randomized to pyrimethamine or matching placebo in a 2:1 allocation (250 receive active treatment and 125 placebo). The remaining half of the patients would be randomized to clindamycin or matching placebo in a 2:1 allocation ratio. Patients and clinicians would know if they are in the clindamycin or pyrimethamine arm but would not know whether they were taking active drug or placebo. After this study design was reviewed, the sponsor requested that the study be fully blinded (double-blind) so that comparisons of active clindamycin and active pyrimethamine would be blinded. Assume patients are to take one 25 mg tablet of pyrimethamine (or matching placebo) by mouth 3 times/week (Monday, Wednesday and Friday), or one 300 mg tablet of clindamycin (or matching placebo) by mouth twice every day (morning and evening). Describe how you would package and distribute the medication to patients in order to conduct the study double-blind. Keep in mind that clindamycin and pyrimethamine can not be made to look alike. Answer: P=Pyrimethamine C=Clindamycin PP = Pyrimethamine Placebo CP = Clindamycin Placebo 1
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Each patient will get two bottles. One will contain either Pyrimethamine or its placebo and a tablet will be taken every Monday, Wednesday and Friday. The other will contain either Clindamycin or its placebo and a tablet will be taken twice every day. Pyrimethamine Clindamycin Placebo M,W,F P PP PP Twice every day CP C CP 3. (10) A clinical trial called ILLUMINATE was published in the November 22, 2007 issue of the New England Journal of Medicine. A commentator on the trial results referred to the result as “yet another example of a failed surrogate marker”. Consider the operational criteria for surrogacy proposed by Prentice (slide 40 of lecture 8) and for each criterion indicate whether the biomarker under study (HDL cholesterol) and intervention (torcetrapib) met the criteria. Based on that, indicate whether you agree with the commentator’s statement.
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assign2_key - Assignment#2 Clinical Trials(100 points Due...

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