title: Attrition in trials evaluating complex interventions for schizophrenia: Systematic review and meta-analysis.
abstract: Essential criteria for the methodological quality and validity of randomized controlled trials are the drop-out rates from both the experimental intervention and the study as a whole. This systematic review and meta-analysis assessed these drop-out rates in non-pharmacological schizophrenia trials. A systematic literature search was used to identify relevant trials with ≥100 sample size and to extract the drop-out data. The rates of drop-out from the experimental intervention and study were calculated with meta-analysis of proportions. Meta-regression was applied to explore the association between the study and sample characteristics and the drop-out rates. 43 RCTs were found, with drop-out from intervention ranging from 0% to 63% and study drop-out ranging from 4% to 71%. Meta-analyses of proportions showed an overall drop-out rate of 14% (95% CI: 13-15%) at the experimental intervention level and 20% (95% CI: 17-24%) at the study level. Meta-regression showed that the active intervention drop-out rates were predicted by the number of intervention sessions. In non-pharmacological schizophrenia trials, drop-out rates of less than 20% can be achieved for both the study and the experimental intervention. A high heterogeneity of drop-out rates across studies shows that even lower rates are achievable.
authors.affiliation: Unit for Social and Community Psychiatry, Newham Centre for Mental Health, Queen Mary University of London, E13 8SP, UK. Electronic address: paulina.szymczynska@qmul.ac.uk.
authors.forename: P
authors.initials: P
authors.lastname: Szymczynska
authors.affiliation: Unit for Social and Community Psychiatry, Newham Centre for Mental Health, Queen Mary University of London, E13 8SP, UK.
authors.forename: S
authors.initials: S
authors.lastname: Walsh
authors.affiliation: Pragmatic Clinical Trials Unit, Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Yvonne Carter Building, 58 Turner Street, London E1 2AB, UK.
authors.forename: L
authors.initials: L
authors.lastname: Greenberg
authors.affiliation: Unit for Social and Community Psychiatry, Newham Centre for Mental Health, Queen Mary University of London, E13 8SP, UK.
authors.forename: S
authors.initials: S
authors.lastname: Priebe
mesh_terms: D058633:Antipyretics / Q000627:therapeutic use*; D003625:Data Collection / Q000706:statistics & numerical data*; D006801:Humans; D010352:Patient Dropouts / Q000706:statistics & numerical data; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D012559:Schizophrenia / Q000628:therapy*
chemical_list: D058633:Antipyretics
keywords: Attrition; Psychosis; Retention; Review; Schizophrenia; Treatment