Progress in understanding the placebo effect and its clinical significance depends on conceptual clarification of this elusive phenomenon and critical appraisal of research bearing on the influence of placebo interventions on clinical outcomes. Here we locate the placebo effect within a typology of modes of healing, distinguish between the observed placebo response in randomized controlled trials and the placebo effect, and examine critically a recent meta-analysis of clinical trials that challenges the reality of the placebo effect.
aIntramural Research Program, National Institute of Mental Health, Department of Clinical Bioethics, Clinical Center, National Institutes of Health, Building 10, Room 1C118, Bethesda, MD 20892-1156, USA
bOffice of the Clinical Director, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
1 The opinions expressed are those of the authors and do not necessarily reflect the position or policy of the National Institutes of Health, the Public Health Service, or the Department of Health and Human Services.
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