Design Paper Design of the Multicenter Australian Study of Epidural Anesthesia and Analgesia in Major Surgery: The MASTER Trial John R.A. Rigg, MBBS, FANZCA, Konrad Jamrozik, DPhil, FAFPHM, Paul S. Myles, MPH, MD, Brendan Silbert, MBBS, FANZCA, Philip Peyton, MBBS, FANCZA, Richard W. Parsons, MSc, PhD, and Karen Collins, BNurs, for the MASTER Trial Study Group Department of Public Health, The University of Western Australia, Nedlands, Western Australia (J.R.A.R., K.J., R.W.P., K.C.); Anaesthesia Research, Alfred Hospital, Melbourne, Victoria, Australia (P.S.M.); St. Vincent’s Hospital, Melbourne, Victoria, Australia (B.S.); and Austin and Repatriation Medical Centre, Melbourne, Victoria, Australia (P.P.) ABSTRACT: The Multicenter Australian Study of Epidural Anesthesia and Analgesia in Major Surgery (The MASTER Trial) was designed to evaluate the possible benefit of epidural block in improving outcome in high-risk patients. The trial began in 1995 and is sched- uled to reach the planned sample size of 900 during 2001. This paper describes the trial design and presents data comparing 455 patients randomized in 21 institutions in Australia, Hong Kong, and Malaysia, with 237 patients from the same hospitals who were eligible but not randomized. Nine categories of high-risk patients were defined as entry criteria for the trial. Protocols for ethical review, informed consent, randomization, clinical anesthesia and analgesia, and perioperative management were determined fol- lowing extensive consultation with anesthesiologists throughout Australia. Clinical and research information was collected in participating hospitals by research staff who may not have been blind to allocation. Decisions about the presence or absence of endpoints were made primarily by a computer algorithm, supplemented by blinded clinical ex- perts. Without unblinding the trial, comparison of eligibility criteria and incidence Address reprint requests to: Clinical Associate Professor John Rigg, Department of Public Health, The University of Western Australia, Nedlands, Western Australia 6907, Australia. E-mail: jrarigg@cyllene. uwa.edu.au. Received July 16, 1999; revised December 14, 1999; accepted December 22, 1999. Controlled Clinical Trials 21:244–256 (2000)  Elsevier Science Inc. 2000 0197-2456/00/$–see front matter 655 Avenue of the Americas, New York, NY 10010 PII S0197-2456(00)00045-3