Hyperbaric oxygen therapy for the treatment of perianal fistulas in 20 patients with Crohn's disease.

"Declaration of personal interests : CAL has no conflicts of interest to declare. KBG has received consultancy fees and/or speaker's honoraria from AbbVie, Celltrion, Ferring, Immunic Therapeutics, Janssen, Pfizer, Roche, Sandoz, Samsung Bioepis, Takeda and Tillotts. CJB has received speakers' honoraria from Takeda and Tillotts. She has an unrestricted grant from Boehringer Ingelheim, and is part of the advisory board of Johnson & Johnson energy devices. ML has served as speaker and/or principal investigator for: Abbvie, Celgene, Covidien, Dr Falk, Ferring Pharmaceuticals, Gilead, GlaxoSmithKline, Janssen‐Cilag, Merck Sharp & Dohme, Pfizer, Protagonist therapeutics, Receptos, Robarts Clinical Trials, Takeda, Tillotts and Tramedico. He has received research grants from AbbVie, Merck Sharp & Dohme, Dr Falk, Achmea healthcare and ZonMW. JS has a research agreement with Takeda on a nonrelated topic. WAB has served as speaker for Takeda, Johnson and Johnson and Braun. He has received research grants from Braun and Vifor. GDH has served as advisor for Abbvie, Ablynx, Active Biotech AB, Agomab Therapeutics, Allergan, Alphabiomics, Amakem, Amgen, AM Pharma, Applied Molecular Therapeutics; Arena Pharmaceuticals, AstraZeneca, Avaxia, Biogen, Bristol Meiers Squibb/Celgene, Boehringer Ingelheim, Celltrion, Cosmo, DSM Pharma; Echo Pharmaceuticals, Eli Lilly, Engene, Exeliom Biosciences; Ferring, DrFALK Pharma, Galapagos, Genentech/Roche, Gilead, Glaxo Smith Kline, Gossamerbio, Pfizer, Immunic, Johnson and Johnson, Kintai Therapeutics, Lycera, Medimetrics, Takeda, Medtronic, Mitsubishi Pharma, Merck Sharp Dome, Mundipharma, Nextbiotics, Novonordisk, Otsuka, Photopill, ProciseDx, Prodigest, Prometheus laboratories/Nestle, Progenity, Protagonist, RedHill; Robarts Clinical Trials, Salix, Samsung Bioepis, Sandoz, Seres/Nestec/Nestle, Setpoint, Shire, Teva, Tigenix, Tillotts, Topivert, Versant and Vifor; received speaker fees from Abbvie, Biogen, Ferring, Galapagos/Gilead, Johnson and Johnson, Merck Sharp Dome, Mundipharma, Norgine, Pfizer, Samsung Bioepis, Shire, Millenium/Takeda, Tillotts and Vifor. RAH has no conflicts of interest to declare."

"Funding information This research has been awarded with a Grant from the European Crohn's and Colitis Organisation and this Grant funded the research. The funder did not have any role in the study design, collection, management, analysis or interpretation of data, or writing of the report or the decision to submit the report for publication."

"The study was performed in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice guidelines. The protocol has been approved by the Medical Ethical Committee (METC 2017_132) and has been published previously. The trial has been registered at the Dutch Trial Registry (NL 6489/NTR 6676). Conclusions: We found significant clinical, radiological and biochemical improvement in Crohn's disease patients with therapy‐refractory perianal fistulas after treatment with hyperbaric oxygen.: Clinical trial registration: www.trialregister.nl/trial/6489."