University of Oulu

Mäkäräinen-Uhlbäck, E., Wiik, H., Kössi, J. et al. Chimney Trial: study protocol for a randomized controlled trial. Trials 20, 652 (2019).

Chimney Trial : study protocol for a randomized controlled trial

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Author: Mäkäräinen-Uhlbäck, Elisa1; Wiik, Heikki1; Kössi, Jyrki2;
Organizations: 1Oulu University Hospital, PL 21, 90029, OYS, Finland
2Päijät-Häme Central Hospital, Keskussairaalankatu 7, 15850, Lahti, Finland
3Västmanlands Hospital Västerås, 721 89, Västerås, Sweden
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.4 MB)
Persistent link:
Language: English
Published: Springer Nature, 2019
Publish Date: 2020-04-28


Background: Parastomal hernias (PSHs) are common, troubling the lives of people with permanent colostomy. In previous studies, retromuscular keyhole mesh placement has been the most-used technique for PSH prevention but results have been controversial. Additionally, surgical treatment of PSHs is associated with a high rate of complications and recurrences. Therefore, it is crucial to find the most effective way to prevent PSHs in the first place without an increased risk of complications. Due to a lack of adequate research, there is no clear evidence or recommendations on which mesh or technique is best to prevent PSHs.

Methods/design: The Chimney Trial is a Nordic, prospective, randomized controlled, multicenter trial designed to compare the feasibility and the potential benefits of specifically designed, intra-abdominal onlay mesh (DynaMesh®-Parastomal, FEG Textiltechnik GmbH, Aachen, Germany) against controls with permanent colostomy without mesh.

The primary outcome of the Chimney Trial is the incidence of a PSH detected by a computerized tomography (CT) scan at 12-month follow-up. Secondary outcomes are the rate of clinically detected PSHs, surgical-site infection as defined by the Centers for Disease Control and Prevention (CDC), complications as defined by the Clavien-Dindo classification, the reoperation rate, operative time, length of stay, quality of life as measured by the RAND-36 survey and colostomy impact score, and both direct and indirect costs. For each group, 102 patients were enrolled at attending hospitals and randomized at a ratio of 1:1 by browser-based software to receive a preventive mesh or a conventional colostomy without a mesh. Patients will be followed for 1 month and at 1, 3, and 5 years after the operation for long-term results and complications.

Discussion: The Chimney Trial aims to provide level-I evidence on PSH prevention.

Trial registration:, ID: NCT03799939. Registered on 10 January 2019.

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Series: Trials
ISSN: 1745-6215
ISSN-E: 1745-6215
ISSN-L: 1745-6215
Volume: 20
Issue: 1
Article number: 652
DOI: 10.1186/s13063-019-3764-y
Type of Publication: A1 Journal article – refereed
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
Funding: The materials used within this study are funded by the hospital district. The Thelma Mäkikyrö Foundation has granted funding of €10,000 to the Chimney Trial. The funding will be used to provide the research nurse for the study and the authors’ time on research.
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.