Placebos and blinding

ICH ElO (2001) Note for Guidance on Choke of Control Group in Clinical Trials  

Control groups can take a variety of forms, here are just a few examples of trials with alternative types of control group  

Open trials with no control group can nonetheless be useful in an exploratory, maybe early phase setting, but it is unlikely that such trials will be able to provide confirmatory, robust evidence regarding the performance of the new treatment. 

Similarly, external or historical controls (groups of subjects external to the study either in a different setting or previously treated) cannot provide definitive evidence. Byar (1980) provides an extensive discussion on these issues. 

It is important to have blinding of both the subject and the investigator wherever possible to avoid unconscious bias creeping in, either in terms of the way a subject reacts psychologically to a treatment or in relation to the way the investigator influences or records subject outcome. 

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The use of placebos and blinding go hand in hand. The existence of placebos enable trials to be blinded and account for the placebo effect the change in a patient s condition that is due to the act of being treated, but is not caused by the active component of that treatment. 

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