{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T20:27:55Z","timestamp":1792787275496,"version":"4.5.0"},"reference-count":11,"publisher":"BMJ","issue":"10","license":[{"start":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T00:00:00Z","timestamp":1791244800000},"content-version":"unspecified","delay-in-days":5,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Netherlands Organization for Health Research and Development","award":["11320102410051"],"award-info":[{"award-number":["11320102410051"]}],"id":[{"id":"https:\/\/ror.org\/01yaj9a77","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2026,9,23]]},"published-print":{"date-parts":[[2026,10]]},"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Cryptoglandular anal fistulas are burdensome, often recurrent and frequently treated in two stages using a loose seton before definitive sphincter-preserving surgery. Although this practice is common, high-quality evidence supporting improved healing or functional outcomes is lacking. A trial is needed to determine whether omitting routine seton placement can reduce procedures, patient burden and costs without compromising fistula closure.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods and analysis<\/jats:title>\n                    <jats:p>The SETON trial is a multicentre, randomised, unblinded non-inferiority trial with an integrated cost-utility analysis. Adults with a single-tract non-purulent mid-high or high cryptoglandular anal fistula will be randomised to loose seton placement for 8 weeks followed by definitive sphincter-preserving surgery, or to direct sphincter-preserving surgery without prior seton placement. The primary endpoint is fistula closure 26 weeks after final surgery, defined clinically and if needed confirmed by MRI or endoanal ultrasound. Secondary outcomes include recurrence, postoperative complications, pain, re-interventions, continence, fistula-related quality of life, generic health-related quality of life, return to work and cost-effectiveness. A sample size has been calculated for a non-inferiority design with fistula closure at 26 weeks as the primary endpoint. Assuming a conservative closure rate of 60% in the standard-care seton group, a one-sided alpha of 0.05, 80% power and a non-inferiority margin of 15\u2009percentage points, 126 patients are required per group for analysis. Allowing for approximately 10% loss to follow-up, the total sample size will be 277 patients. Data will be analysed according to the intention-to-treat and per-protocol principle.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Ethics and dissemination<\/jats:title>\n                    <jats:p>The protocol has been approved by the Medical Ethics Review Committee of the Amsterdam University Medical Center, location AMC (reference number: 2025.0826\u2014NL-010338 R031541). Findings will be disseminated in peer-reviewed journals and presented at conferences, whether they are positive, negative or inconclusive.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Trial registration number<\/jats:title>\n                    <jats:p>NL-010338<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2026-122832","type":"journal-article","created":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T13:20:39Z","timestamp":1791292839000},"page":"e122832","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Does omission of a loose seton before sphincter-preserving surgery achieve non-inferior fistula closure compared with routine loose seton placement in adults with single-tract cryptoglandular anal fistula in the Netherlands?\n                    <b>Study protocol for the SETON multicentre randomised controlled non-inferiority trial and cost-utility<\/b>\n                    analysis"],"prefix":"10.1136","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-3836-0429","authenticated-orcid":false,"given":"Ahmed A","family":"Elwakel","sequence":"first","affiliation":[{"name":"Department of Surgery, Amsterdam UMC, Amsterdam, The Netherlands"},{"name":"Department of Surgery, Proctos Kliniek, Bilthoven, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pieter","family":"Van Hagen","sequence":"additional","affiliation":[{"name":"Department of Surgery, Proctos Kliniek, Bilthoven, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ruben","family":"Veldkamp","sequence":"additional","affiliation":[{"name":"Department of Surgery, Proctos Kliniek, Bilthoven, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susan","family":"van Dieren","sequence":"additional","affiliation":[{"name":"Department of Surgery, Amsterdam UMC, Amsterdam, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Willem A","family":"Bemelman","sequence":"additional","affiliation":[{"name":"Department of Surgery, Amsterdam UMC, Amsterdam, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ingrid J M","family":"Han-Geurts","sequence":"additional","affiliation":[{"name":"Department of Surgery, Proctos Kliniek, Bilthoven, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,10,6]]},"reference":[{"key":"2026100606201917000_16.10.e122832.1","unstructured":"Dunker M , Wijffels N , Lahaye M , et al . Richtlijn proctologie. nederlandse vereniging voor heelkunde & nederlandse vereniging voor gastro-enterologie. 2020. Available: https:\/\/richtlijnendatabase.nl"},{"key":"2026100606201917000_16.10.e122832.2","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1111\/codi.16741","article-title":"European Society of Coloproctology: Guidelines for diagnosis and treatment of cryptoglandular anal fistula","volume":"26","author":"Reza","year":"2024","journal-title":"Colorectal Dis"},{"key":"2026100606201917000_16.10.e122832.3","doi-asserted-by":"publisher","DOI":"10.1007\/s00384-010-0993-7"},{"key":"2026100606201917000_16.10.e122832.4","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1007\/s10151-020-02156-2","article-title":"How is your proctology patient really doing? Outcome measurement in proctology: development, design and validation study of the Proctoprom","volume":"24","author":"Vander Mijnsbrugge","year":"2020","journal-title":"Tech Coloproctol"},{"key":"2026100606201917000_16.10.e122832.5","doi-asserted-by":"crossref","first-page":"857","DOI":"10.1007\/DCR.0b013e31820eee2e","article-title":"Is the Outcome of Transanal Advancement Flap Repair Affected by the Complexity of High Transsphincteric Fistulas?","volume":"54","author":"Mitalas","year":"2011","journal-title":"Diseases of the Colon & Rectum"},{"key":"2026100606201917000_16.10.e122832.6","article-title":"Ligation of Intersphincteric Fistula Tract Is Suitable for Recurrent Anal Fistulas from Follow-Up of 16 Months","volume":"2017","author":"Xu","year":"2017","journal-title":"Biomed Res Int"},{"key":"2026100606201917000_16.10.e122832.7","unstructured":"Hakkaart-van Roijen L , Linden N , Bouwmans C , et al . Kostenhandleiding: Methodologie van kostenonderzoek en referentieprijzen voor economische evaluaties in de gezondheidszorg (geactualiseerde versie 2016). Erasmus Universiteit Rotterdam: Institute for Medical Technology Assessment (iMTA), 2016."},{"key":"2026100606201917000_16.10.e122832.8","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1016\/j.jval.2016.01.003","article-title":"Dutch Tariff for the Five-Level Version of EQ-5D","volume":"19","author":"M. Versteegh","year":"2016","journal-title":"Value in Health"},{"key":"2026100606201917000_16.10.e122832.9","doi-asserted-by":"publisher","DOI":"10.1016\/j.jval.2013.08.2291"},{"key":"2026100606201917000_16.10.e122832.10","doi-asserted-by":"publisher","DOI":"10.1111\/j.1524-4733.2007.00187.x"},{"key":"2026100606201917000_16.10.e122832.11","unstructured":"Nederlandse Zorgautoriteit (NZa) . Open dis-data over zorgproducten en tarieven. Geraadpleegd via; 2014. 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