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Perry Cohen, Ph.D. presents Sham Neurosurgical Procedures in Clinical Trials:  Patient Activists’ Perspectives at the NIH conference
Sham Neurosurgical Procedures in Clinical Trials for Neurodegenerative Diseases: Scientific and Ethical Considerations
held on June 30 and July 1, 2010

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This slide describes characteristics of the gold standard for medical science. The major point is that for evaluation of new therapies the FDA law requires well controlled randomized clinical trials (RCT), but  not blinded placebo controls.  In practice the FDA goes beyond the requirements of the law and insists on this standard based on the scientific consensus that it is necessary to control for the extraordinarily strong placebo effects found with brain surgery.  The goal of my remarks is to examine the assumptions of the experimental design from a patient perspective and to raise questions that must be answered to maintain the validity of this standard.


Double blind, randomized, placebo controlled, prospective clinical trials have been anointed by the Cochrane collaborative (an international professional group that has established standards for quality of scientific evidence in medicine) to be the most rigorous research design. We all know this.

The sample of patients are randomly assigned to one of two or more artificial groups (a sham control group and a treatment group) for comparison purposes only to distinguish between the effects from the social context of delivering the treatment (placebo) and the effects of introducing an active biochemical agent into the brain.

  • Randomized assignment is the statistical method of balancing all the non-studied factors that are assumed to have no net effect on the health outcome.

  • Blinding is the method for preventing the knowledge of the assignment of the patient from biasing the results

    • Single blind for researchers. This is the major source of error given the standard outcome for PD research is a set of clinical rating scales (UPDRS)

    • Double blind for patients/providers

The underlying linear statistical model assumes that the causal factors (treatments and controls) are independent variables and thus assumes that there are no interactions between the placebo and the treatment. In this way the difference between the treatment group and the placebo group can be a measure of ‘real’ treatment effects attributed to the biochemical activity of the treatment alone above the psycho-social effects of the placebo.

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