Investigation of the Placebo Effect in a Longitudinal Double-Blind Surgical Trial

University Of Denver (Colorado Seminary), Denver CO

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Abstract

[unreadable] DESCRIPTION (provided by applicant): Between 1995 and 2000 a double-blind sham surgery-controlled trial was conducted to determine the effectiveness of stereotactic transplantation of human embryonic dopamine neurons into the brains of persons with advanced Parkinson's disease. Forty patients were randomly assigned to receive either neural tissue transplantation or sham surgery. Patients in the double-blind trial, or "parent" study, were also invited to participate in a related and ongoing assessment of quality of life (QoL). Thirty patients agreed to participate; 12 originally received the transplant and 18 received sham surgery. Twelve sham surgery patients elected to have the transplant after the blind was lifted approximately one year after surgery. Twenty spousal caregivers also agreed to participate. Questionnaires assessing three primary domains of QoL, Physical, Emotional, and Social functioning, were sent to patients and caregivers at baseline, 4, 8, 12, 18, and 24 months after surgery and semi-annually thereafter for an average of 3 years. The objectives of the QoL study were to determine whether QoL improved more in the transplant group than in the sham surgery group, and to investigate outcomes over the course of the double-blind based on perceived treatment, or the type of surgery patients thought they received. Results of both the "parent" and QoL studies indicated few differences between the transplant and sham surgery groups by 12 months. However, results based on the type of surgery patients thought they received at each of the follow-up assessment periods of 4, 8, and 12 months were stronger and more significant than results based on the type of surgery patients actually received (McRae et al., 2004). Thus, there was a strong placebo effect which continued over the 12 month period of the double-blind. These compelling results suggest several questions relevant to public health and future research related to placebo treatments that will be addressed in secondary analyses of the quality of life and medical data collected during the original fetal transplant study (Freed et al., 2001). These additional analyses will allow a unique opportunity to examine several important aspects of the placebo effect. This study will address the following Specific Aims: 1) To determine the variables most strongly related to perceived treatment at 4, 8, and 12 months; 2) To determine whether there are differences in outcome over the first 12 months after the transplant based upon receiving the transplant under the double-blind condition (Transplant,) versus the unblinded condition (Transplant2; patients who received the sham first and later received the transplant); and 3) To determine whether there were differences in spousal caregiver ratings of patient functioning, as well as caregiver functioning, based on actual and patient perceived treatment at 4, 8, and 12 months. [unreadable] [unreadable] [unreadable]