Jamieson et al. J Cardiothorac Surg (2021) 16:323 https://doi.org/10.1186/s13019-021-01632-6 RESEARCH ARTICLE PROSE: Prospective Randomized Trial of the On-X Mechanical Prosthesis and the St Jude Medical Mechanical Prosthesis Evaluation Part 1(Patient Dynamics): Preoperative demographics and preoperative and operative risk factors W. R. Eric Jamieson 1* , John L. Ely 2 , Johan Brink 3 , Timothy Pennel 3 , Paul Bannon 4 , Jashvant Patel 5 , Rajiv Kumar Gupta 6 , Prasanna Simha Mohan Rao 7 , Damyanti Agrawal 8 , Lars Wiklund 9 , A. Pieter Kappetein 10 , Rune Haaverstad 11 , Thomas Geisner 11 , Torsten Doenst 12 , Christian Schlensak 13 , Salgunan Nair 14 , Craig Brown 15 , Matthias Siepe 16 , Ralph J. Damiano 17 , Yves Langlois 18 , K. M. Cherian 19 , Hormoz Azar 20 , John C. Chen 21 , Joseph E. Bavaria 22 , Lynn M. Fedoruk 23 , Nabil A. Munfakh 17 , V. Sridhar 24 , Peter M. Scholz 25 , Thomas A. Pfeffer 26 and Jian Ye 1 Abstract Objectives: The PROSE trial purpose is to investigate whether the incidence of thromboembolic—related complica- tions is reduced with a current generation mechanical prosthesis (On-X Life Technologies/CryoLife Inc.—On-X) com- pared with a previous generation mechanical prosthesis (St Jude Medical—SJM). The primary purpose of the initial report is to document the preoperative demographics, and the preoperative and operative risk factors by individual prosthesis and by Western and Developing populations. Methods: The PROSE study was conducted in 28 worldwide centres and incorporated 855 subjects randomized between 2003 and 2016. The study enrollment was discontinued on August 31, 2016. The preoperative demographics incorporated age, gender, functional class, etiology, prosthetic degeneration, primary rhythm, primary valve lesion, weight, height, BSA and BMI. The preoperative and operative evaluation incorporated 24 risk factors. Results: The total patient population (855) incorporated On-X population (462) and the St Jude Medical popula- tion (393). There was no significant difference of any of the preoperative demographics between the On-X and SJM groups. The preoperative and operative risk factors evaluation showed there was no significant difference between the On-X and St Jude Medical populations. The preoperative and operative risk factors by valve position (aortic and mitral) also documented no differentiation. The dominant preoperative demographics of the Western world popula- tion were older age, male gender, sinus rhythm, aortic stenosis, congenital aortic lesion, and mitral regurgitation. The dominant demographics of the Developing world population were rheumatic etiology, atrial fibrillation, aortic regurgitation, mixed aortic lesions, mitral stenosis and mixed mitral lesions. The Developing world group had only one © The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Open Access *Correspondence: wreric.jamieson@gmail.com 1 Vancouver Coastal Health Research Institute, University of British Columbia, Vancouver, Canada Full list of author information is available at the end of the article