The Quantification of Placebo Effects Within a General Model of Health Care Outcomes

Objectives: The objective of this study was to test a model of placebo effects in the context of a general model of health care outcomes. Design: The design of this study was a multisite, double-blind, placebo-controlled crossover trial. Settings: The study was conducted at The University of Washington Hospital, Seattle, Washington, Cooper Hospital/University Medical Center, Camden, New Jersey, and at the Neurology Center of Fairfax, Fairfax, Virginia. Subjects: One hundred and seventeen (117) patients diagnosed with Multiple Sclerosis were enrolled in the study. Intervention: Subjects had daily exposure to a pulsing electromagnetic generator. Outcome measures: The outcome measures were the average score of three quality-of-life indices: the Modified Fatigue Impact Scale, the Medical Outcomes Study Pain Effects Scale, and the Spasticity Effects Scale. Results: Placebo responders scored higher in the personality trait of Absorption compared with nonresponders (p < 0.01). Placebo responders were more confident that the sham device was active compared to placebo nonresponders (p < 0.009). The two factors of confidence in the treatment and Absorption accurately identified 80% of placebo responders in a discriminant analysis (p < 0.0004). Conclusions: Placebo effects are best understood when integrated in a general model of health care outcomes.