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.