title: Toward evidence-based medical statistics: a Bayesian analysis of double-blind placebo-controlled antidepressant trials in the treatment of anxiety disorders.
abstract: The Food and Drug Administration (FDA) uses a p < 0.05 null-hypothesis significance testing framework to evaluate "substantial evidence" for drug efficacy. This framework only allows dichotomous conclusions and does not quantify the strength of evidence supporting efficacy. The efficacy of FDA-approved antidepressants for the treatment of anxiety disorders was re-evaluated in a Bayesian framework that quantifies the strength of the evidence. Data from 58 double-blind placebo-controlled trials were retrieved from the FDA for the second-generation antidepressants for the treatment of anxiety disorders. Bayes factors (BFs) were calculated for all treatment arms compared to placebo and were compared with the corresponding p-values and the FDA conclusion categories. BFs ranged from 0.07 to 131,400, indicating a range of no support of evidence to strong evidence for the efficacy. Results also indicate a varying strength of evidence between the trials with p < 0.05. In sum, there were large differences in BFs across trials. Among trials providing "substantial evidence" according to the FDA, only 27 out of 59 dose groups obtained strong support for efficacy according to the typically used cutoff of BF ≥ 20. The Bayesian framework can provide valuable information on the strength of the evidence for drug efficacy. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Interdisciplinary Center Psychopathology and Emotion regulation (ICPE), Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Rei
authors.initials: R
authors.lastname: Monden
authors.affiliation: Interdisciplinary Center Psychopathology and Emotion regulation (ICPE), Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Stijn
authors.initials: S
authors.lastname: de Vos
authors.affiliation: Faculty of Behavioral and Social Sciences, University of Groningen, Groningen, The Netherlands.
authors.forename: Richard
authors.initials: R
authors.lastname: Morey
authors.affiliation: Department of Experimental Psychology, University of Groningen, Groningen, The Netherlands.
authors.forename: Eric-Jan
authors.initials: EJ
authors.lastname: Wagenmakers
authors.affiliation: Interdisciplinary Center Psychopathology and Emotion regulation (ICPE), Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: de Jonge
authors.affiliation: Interdisciplinary Center Psychopathology and Emotion regulation (ICPE), Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Annelieke M
authors.initials: AM
authors.lastname: Roest
mesh_terms: D000928:Antidepressive Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001008:Anxiety Disorders / Q000188:drug therapy*; D001499:Bayes Theorem; D018849:Controlled Clinical Trials as Topic / Q000706:statistics & numerical data*; D004311:Double-Blind Method; D055317:Evidence-Based Practice; D006801:Humans; D017063:Outcome Assessment, Health Care / Q000379:methods*
chemical_list: D000928:Antidepressive Agents
keywords: Bayes factor; Bayesian statistics; FDA; second-generation antidepressants; significance testing