Science and ethics of sham surgery: a survey of Parkinson disease clinical researchers.

Background Sham surgery is used in neurosurgical clinical trials in Parkinson disease (PD) but remains controversial. The controversy may be compounded when gene-transfer technologies are tested in sham surgical trials. Objective To determine the perspective of PD clinical researchers on the science and ethics of sham-surgery controls when used to test novel interventions such as gene transfer for PD. Design Internet survey eliciting both quantitative and qualitative responses. Participants Investigator members of the Parkinson Study Group. Results Overall response rate was 103 (61.3%) of 168 researchers. A large majority (97%) of PD clinical researchers believe sham-surgery controls are better than unblinded controls for testing the efficacy of neurosurgical interventions such as gene transfer for PD. Half of the researchers believe an unblinded control efficacy trial would be unethical because it may lead to a falsely positive result. A minority (less than 22%) believe that an invasive sham condition that involves penetration of brain tissue is justified. Conclusion It appears unlikely that the PD clinical research community will perceive future neurosurgical interventions for PD, such as gene-transfer therapies, as truly efficacious unless a sham-control condition is used to test it.