title: Impure placebo is a useless concept.
abstract: Placebos are allegedly used widely in general practice. Surveys reporting high level usage, however, have combined two categories, 'pure' and 'impure' placebos. The wide use of placebos is explained by the high level usage of impure placebos. In contrast, the prevalence of the use of pure placebos has been low. Traditional pure placebos are clinically ineffective treatments, whereas impure placebos form an ambiguous group of diverse treatments that are not always ineffective. In this paper, we focus on the impure placebo concept and demonstrate problems related to it. We also show that the common examples of impure placebos are not meaningful from the point of view of clinical practice. We conclude that the impure placebo is a scientifically misleading concept and should not be used in scientific or medical literature. The issues behind the concept, however, deserve serious attention in future research.
authors.affiliation: Department of Public Health, University of Helsinki, P.O. Box 41, 00014, Helsinki, Finland, pekka.louhiala@helsinki.fi.
authors.forename: Pekka
authors.initials: P
authors.lastname: Louhiala
authors.forename: Harri
authors.initials: H
authors.lastname: Hemilä
authors.forename: Raimo
authors.initials: R
authors.lastname: Puustinen
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D003210:Concept Formation; D058006:General Practice / Q000379:methods / Q000592:standards; D006801:Humans; D008419:Materia Medica / Q000008:administration & dosage; D036142:Mentha piperita; D010808:Physical Examination; D010817:Physician-Patient Relations; D008517:Phytotherapy; D015990:Placebo Effect; D010919:Placebos; D010936:Plant Extracts / Q000008:administration & dosage; D019936:Probiotics / Q000008:administration & dosage; D011788:Quality of Life; D013404:Suggestion; D009626:Terminology as Topic; D014815:Vitamins / Q000008:administration & dosage
chemical_list: D000900:Anti-Bacterial Agents; D008419:Materia Medica; D010919:Placebos; D010936:Plant Extracts; D014815:Vitamins