title: The utility of Bayesian predictive probabilities for interim monitoring of clinical trials.
abstract: BACKGROUND
  Bayesian predictive probabilities can be used for interim monitoring of clinical trials to estimate the probability of observing a statistically significant treatment effect if the trial were to continue to its predefined maximum sample size.
  
  
  OBJECTIVE
  We explore settings in which Bayesian predictive probabilities are advantageous for interim monitoring compared to Bayesian posterior probabilities, p-values, conditional power, or group sequential methods.
  
  
  RESULTS
  For interim analyses that address prediction hypotheses, such as futility monitoring and efficacy monitoring with lagged outcomes, only predictive probabilities properly account for the amount of data remaining to be observed in a clinical trial and have the flexibility to incorporate additional information via auxiliary variables.
  
  
  CONCLUSIONS
  Computational burdens limit the feasibility of predictive probabilities in many clinical trial settings. The specification of prior distributions brings additional challenges for regulatory approval.
  
  
  CONCLUSIONS
  The use of Bayesian predictive probabilities enables the choice of logical interim stopping rules that closely align with the clinical decision-making process.
authors.affiliation: Department of Biostatistics, School of Medicine, Vanderbilt University, Nashville, TN, USA b.saville@vanderbilt.edu.
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Saville
authors.affiliation: Berry Consultants, Austin, TX, USA College of Medicine, University of Central Florida, Orlando, FL, USA.
authors.forename: Jason T
authors.initials: JT
authors.lastname: Connor
authors.affiliation: Department of Biostatistics, School of Medicine, Vanderbilt University, Nashville, TN, USA.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Ayers
authors.affiliation: Department of Biostatistics, School of Medicine, Vanderbilt University, Nashville, TN, USA.
authors.forename: JoAnn
authors.initials: J
authors.lastname: Alvarez