title: Placebo effects on itch: a meta-analysis of clinical trials of patients with dermatological conditions.
abstract: Although placebo contributes to the effects of treatment for various symptoms and conditions, its effect on itch has rarely been investigated. In this meta-analysis, the magnitude of the placebo effect on itch was systematically investigated in clinical trials including patients with chronic itch due to atopic dermatitis, psoriasis, or chronic idiopathic urticaria. From searches in four databases, 34 articles were included in the quantitative analyses. Placebo treatment significantly decreased itch (1.3 out of 10, 95% confidence interval 1.02-1.61) compared with baseline itch (effect size 0.55), indicating that placebo effects have a considerable role in these patients' treatment.
authors.affiliation: Unit Health, Medical and Neuropsychology, Faculty of Social and Behavioural Sciences, Leiden University, Leiden, The Netherlands; Leiden Institute for Brain and Cognition (LIBC), Leiden University, Leiden, The Netherlands; Department of Medical Psychology, Radboud University Medical Center, Nijmegen, The Netherlands. Electronic address: A.vanlaarhoven@fsw.leidenuniv.nl.
authors.forename: Antoinette I M
authors.initials: AIM
authors.lastname: van Laarhoven
authors.affiliation: Unit Health, Medical and Neuropsychology, Faculty of Social and Behavioural Sciences, Leiden University, Leiden, The Netherlands.
authors.forename: Ineke M
authors.initials: IM
authors.lastname: van der Sman-Mauriks
authors.affiliation: Department for Health Evidence, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: A Rogier T
authors.initials: ART
authors.lastname: Donders
authors.affiliation: Unit Health, Medical and Neuropsychology, Faculty of Social and Behavioural Sciences, Leiden University, Leiden, The Netherlands.
authors.forename: Mathilde C
authors.initials: MC
authors.lastname: Pronk
authors.affiliation: Department of Dermatology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Peter C M
authors.initials: PCM
authors.lastname: van de Kerkhof
authors.affiliation: Unit Health, Medical and Neuropsychology, Faculty of Social and Behavioural Sciences, Leiden University, Leiden, The Netherlands; Leiden Institute for Brain and Cognition (LIBC), Leiden University, Leiden, The Netherlands; Department of Medical Psychology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Andrea W M
authors.initials: AWM
authors.lastname: Evers
mesh_terms: D000982:Antipruritics / Q000627:therapeutic use*; D018849:Controlled Clinical Trials as Topic; D003876:Dermatitis, Atopic / Q000150:complications; D005260:Female; D006801:Humans; D008297:Male; D015990:Placebo Effect; D011537:Pruritus / Q000188:drug therapy* / Q000209:etiology / Q000523:psychology*; D011565:Psoriasis / Q000150:complications; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014581:Urticaria / Q000150:complications
chemical_list: D000982:Antipruritics