OCEaN - Optimisation before Crohn's surgery using Exclusive enteral Nutrition


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Crohn’s disease (CD) is a chronic inflammatory disease of the gastrointestinal tract, with increasing incidence worldwide. In the UK, it is predicted that the prevalence of inflammatory bowel disease (IBD) will be 1% by 2030. Medication such as oral immunosuppressants and biologics are the mainstay of treatment for CD, however, surgery continues to have a role in disease management.

 The main indications for surgery are stricturing disease, penetrating complications and medication-refractory inflammatory disease. There is some suggestion that the current more aggressive treat to target approach has reduced surgical rates. Despite this 23-47% of patients still require surgery at some stage in their disease course. Some patients also require repeated surgery.

 Surgery may be the preferred first line treatment as per the LIR!C study which showed that primary ileocaeal resection in patients with isolated ileocaecal disease had similar quality of life scores one year after surgery as compared to medical treatment. The European Crohn’s and Colitis Organisation (ECCO) and European Society of Coloproctology (ESCP) consensus guidelines suggest surgery should be considered at an early stage in those with penetrating or fistulising disease and those with localised ileocecal disease and obstructive symptoms but no significant active inflammation.

  Exclusive Enteral Nutrition (EEN) is the term used when a patient replaces their habitual diet with an exclusive liquid diet for a defined period of time. EEN is widely used in paediatric CD as first line therapy for induction of remission without the use of steroids. Six to eight weeks is the recommended duration of EEN with induction of remission of CD occurring in 60-80% of children and adolescents. To date, there have been no randomised controlled trials (RCT) looking at the ability of EEN to induce remission in adults compared to usual unrestricted diet, and a Cochrane review showed that EEN was effective, but inferior to steroids; perhaps due to lack of compliance with EEN.

 The National Institute of Clinical Excellence (NICE) as well as surgical, nutrition, and gastroenterological societies in the UK and internationally have highlighted the need for prospective RCT to determine whether pre-operative EEN is beneficial in surgical outcomes for CD. The James Lind alliance also highlighted the importance of research into the role of diet and EEN in CD.

 Surgery remains an important part of the management of CD and cost-effective measures that may reduce complications and ensure proper resource utilisation need to be investigated. Evidence for the pre-operative use of EEN from systematic reviews has highlighted that there is sufficient indication from retrospective studies that EEN may be effective and hence a large prospective RCT is now required to inform future care. 

 This prospective multicentre randomised study aims to define the role of EEN in the pre-operative management of CD. 


Multi-Centre, Two arm, Parallel group, Open label, Pragmatic Randomised Controlled Trial, with a mixed methods internal pilot (assessing both quantitative and qualitative data) and full economic evaluation. 

 Participants will be randomised to six weeks of pre-operative EEN vs. standard care. 

Aim of the Study

The primary aim of this study is to determine whether pre-operative Exclusive Enteral Nutrition (EEN) is more clinically and cost effective compared with usual diet in patients undergoing surgery for Crohn’s disease (CD). 


40 UK-wide NHS hospitals including tertiary centres and District General Hospitals (DGHs). 

Target Population

Adult patients having planned surgery for small bowel and / or colonic CD (primary or repeat surgery). 


Six weeks of EEN prior to surgery vs usual diet as per local standard care.

Measurement of outcomes

Patient-reported outcomes 

  • Quality of life over time (CLIQ will be collected fortnightly until twelve weeks post-surgery and then monthly to six months post-surgery)
  • Post-surgery recovery using the Surgical Quality of Recovery-15 (QoR-15) on day 3 post-surgery (or pre-discharge if discharged before day 3)

Clinical outcomes 

  • Length of post-operative hospital stay (in nights following operation) 
  • Length of bowel resected (in centimetres measured along antimesenteric border) measured at the time of surgery
  • Number of anastomoses formed at surgery
  • Proportion of patients requiring stoma formation documented at six weeks post discharge
  • Proportion of patients who develop an anastomotic leak
  • Proportion of patients whose planned surgery did not proceed due to clinical improvement
  • Proportion of patients who required expedited surgery
  • Proportion of patients re-admitted within 30 days of discharge
  • Proportion of patients requiring re-operation within 30 days of surgery
  • Proportion of patients who develop enterocutaneous fistulae within 90 days of surgery
  • Proportion of patients who develop clinical recurrence of their CD at 6 and 12 months as assessed by Crohn’s disease activity index
  • Proportion of patients who develop endoscopic disease recurrence at 6-12 months
  • Proportion of patients on steroids who were able to wean off steroids prior to surgery
  • Safety assessed through adverse event and serious adverse event reporting

 Other clinical outcomes 

  • Change in faecal calprotectin levels, Crohn’s Disease Activity Index (CDAI) and Harvey Bradshaw Index (HBI) between start and end of EEN / standard diet pre-operatively 

 Health economic analysis 

  • EQ-5D-5L questionnaire and an incremental cost-utility analysis will determine the cost per quality adjusted life year (QALY) gained over the 12 months post-surgery. 

 Qualitative Research 

  • Qualitative research interviews will be undertaken with patients allocated both trial groups, and also with staff.  This research aims to provide in-depth qualitative data concerning the acceptability and experience of EEN as a pre-surgical intervention. 

Key Eligibility Criteria

Inclusion criteria 

  • Any patient undergoing planned surgery for small bowel and / or colonic CD. 
  • Age ≥16 years 
  • Willingness to go on EEN for the duration of the intervention period (6 to a maximum of 12 weeks) 
  • Capacity to give consent 

 Exclusion criteria 

  • Surgery for peri-anal CD, ulcerative colitis, or indeterminate colitis 
  • Enteral diet contra-indicated 
  • Patients who require parenteral nutrition in the pre-operative period 
  • Patients with a current diagnosis of eating disorder 
  • Pregnancy.
  • Vegans who are unwilling to take EEN (there is no currently commercially available vegan liquid oral feed) 
  • Inability to comply with the trial schedule and follow up 


Funding Scheme: National Institute for Health Research, Health Technology Assessment (NIHR HTA) 

 Funder’s reference number: NIHR 133657 

 Funding call: 20/133 Pre-operative exclusive enteral nutrition for Crohn’s disease 

More information...

Coordinating Centre: Birmingham Clinical Trials Unit (BCTU)

 Sponsor: University of Birmingham


 EudraCT No: TBC