title: Representativeness of clinical PET study participants with schizophrenia: A systematic review.
abstract: While positron emission tomography (PET) studies have provided invaluable data on antipsychotic effects, selection bias remains a serious concern. A systematic review of PET studies that measured dopamine D2receptor blockade with antipsychotics was conducted to examine their inclusion/exclusion criteria, using PubMed, EMBASE, and ClinicalTrials.gov (last search, September 2016). PET studies were included if they measured D2receptor occupancy in patients with schizophrenia and included introduction of antipsychotic treatment or antipsychotic regimen change in a systematic manner. Twenty-six studies were identified. Age limit was included in 13 studies; one study solely included geriatric patients while others targeted younger adults. Eleven, 6, and 3 studies specifically targeted clinically stable patients, patients with severe psychopathology, and antipsychotic-free patients, respectively. Nineteen and 18 studies excluded patients with physical comorbidity and substance abuse, respectively. As a result, the mean age of subjects ranged from 23 to 42 years when one study that targeted geriatric patients was excluded. Mean Positive and Negative Syndrome Scale total scores ranged from 54 to 95. No comparison active-drug or placebo arm was employed in 24 studies. Blind assessment of symptomatology was performed in 5 studies. In general, subjects participating in clinical PET studies were relatively young, presented with mild symptomatology, and were free from substance abuse or physical comorbidities. These characteristics need to be taken into account when clinical PET data are interpreted. On the other hand, it should also be noted that this study was only qualitative and conservative interpretation is necessary for possibility of subjective bias.
authors.affiliation: Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan.
authors.forename: So
authors.initials: S
authors.lastname: Kirino
authors.affiliation: Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan; Department of Psychiatry, Inokashira Hospital, Tokyo, Japan.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan; Department of Psychiatry, University of Toronto, Ontario, Canada; Schizophrenia Division, Complex Care & Recovery Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Takeuchi
authors.affiliation: Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Mimura
authors.affiliation: Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan; Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada. Electronic address: hiroyuki.uchida.hu@gmail.com.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Uchida
mesh_terms: D000328:Adult; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data; D016208:Databases, Factual / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography; D012559:Schizophrenia / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Antipsychotic; Dopamine; Dopamine D(2) receptor; Positron emission tomography; Schizophrenia