University of Oulu

Saarinen, T., Meriläinen, S., Koivukangas, V. et al. Prospective randomized controlled trial comparing the efficacy and safety of Roux-en-Y gastric bypass and one-anastomosis gastric bypass (the RYSA trial): trial protocol and interim analysis. Trials 20, 803 (2019).

Prospective randomized controlled trial comparing the efficacy and safety of Roux-en-Y gastric bypass and one-anastomosis gastric bypass (the RYSA trial) : trial protocol and interim analysis

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Author: Saarinen, Tuure1; Meriläinen, Sanna2; Koivukangas, Vesa2;
Organizations: 1Department of Gastrointestinal Surgery, Helsinki University Hospital, Abdominal Center, Haartmaninkatu 4, 00029 HUS, Helsinki, Finland
2Department of Surgery, Oulu University Hospital, Oulu, Finland
3Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland
4Department of Endocrinology, Helsinki University Hospital, Abdominal Center, Helsinki, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.1 MB)
Persistent link:
Language: English
Published: Springer Nature, 2019
Publish Date: 2020-04-24


Introduction: There is a lack of prospective studies comparing Roux-en-Y gastric bypass (RYGB) and one-anastomosis gastric bypass (OAGB). Also, the effects of bariatric surgery and weight loss need a deeper understanding through metabolic studies. We describe the trial protocol and interim analysis of a prospective randomized controlled study comparing RYGB and OAGB: the RYSA trial.

Materials and methods: In total, 120 bariatric patients will be randomized between RYGB and OAGB in two academic centers. All patients will be followed up for 10 years with analysis and measurements of weight, comorbidities, blood tests, body composition and questionnaires. Extensive metabolic analyses (mixed meal tests, energy expenditure, biopsies of muscle and subcutaneous fat, urine, saliva and fecal samples) will be carried out in the Obesity Research Unit, University of Helsinki, for all patients treated at the Helsinki University Hospital (80 patients) at baseline, 6 months and 12 months. Bile reflux will be studied for the OAGB group at the Helsinki University Hospital at 6 months with gastroscopy and scintigraphy.

Results: At an interim analysis at 3 months (half-way) through recruitment (30 RYGB and 30 OAGB patients) there have been no deaths and no intensive care unit admittances. One patient in both groups required additional gastroscopy, with anastomosis dilatation in the RYGB group but with no additional intervention in the OAGB group.

Conclusion: The trial can be safely carried out. Recruitment is estimated to be complete by the end of 2019.

Trial registration: Clinical Trials Identifier NCT02882685. Registered on August 30th 2016.

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Series: Trials
ISSN: 1745-6215
ISSN-E: 1745-6215
ISSN-L: 1745-6215
Volume: 20
Issue: 1
Article number: 803
DOI: 10.1186/s13063-019-3898-y
Type of Publication: A1 Journal article – refereed
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
Funding: The study was supported by the Academy of Finland (272376, 266286, 314383), Finnish Medical Foundation, Finnish Diabetes Research Foundation, Novo Nordisk Foundation, Gyllenberg Foundation, Sigrid Juselius Foundation, Helsinki University Hospital Research Funds, Government Research Funds and the University of Helsinki. The funders had no role in planning the study design, data collection and analysis, the decision to publish, or the preparation of the article.
Copyright information: © The Author(s). 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.